1 /*
   2  * Copyright (c) 1996, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 /*
  27  * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved
  28  * (C) Copyright IBM Corp. 1996 - 1999 - All Rights Reserved
  29  *
  30  * The original version of this source code and documentation
  31  * is copyrighted and owned by Taligent, Inc., a wholly-owned
  32  * subsidiary of IBM. These materials are provided under terms
  33  * of a License Agreement between Taligent and Sun. This technology
  34  * is protected by multiple US and International patents.
  35  *
  36  * This notice and attribution to Taligent may not be removed.
  37  * Taligent is a registered trademark of Taligent, Inc.
  38  *
  39  */
  40 
  41 package java.util;
  42 
  43 import java.io.IOException;
  44 import java.io.InputStream;
  45 import java.io.UncheckedIOException;
  46 import java.lang.ref.Reference;
  47 import java.lang.ref.ReferenceQueue;
  48 import java.lang.ref.SoftReference;
  49 import java.lang.ref.WeakReference;
  50 import java.lang.reflect.Constructor;
  51 import java.lang.reflect.InvocationTargetException;
  52 import java.lang.reflect.Modifier;
  53 import java.net.JarURLConnection;
  54 import java.net.URL;
  55 import java.net.URLConnection;
  56 import java.security.AccessController;
  57 import java.security.PrivilegedAction;
  58 import java.security.PrivilegedActionException;
  59 import java.security.PrivilegedExceptionAction;
  60 import java.util.concurrent.ConcurrentHashMap;
  61 import java.util.concurrent.ConcurrentMap;
  62 import java.util.jar.JarEntry;
  63 import java.util.spi.ResourceBundleControlProvider;
  64 import java.util.spi.ResourceBundleProvider;
  65 import java.util.stream.Collectors;
  66 import java.util.stream.Stream;
  67 
  68 import jdk.internal.loader.BootLoader;
  69 import jdk.internal.access.JavaUtilResourceBundleAccess;
  70 import jdk.internal.access.SharedSecrets;
  71 import jdk.internal.reflect.CallerSensitive;
  72 import jdk.internal.reflect.Reflection;
  73 import sun.security.action.GetPropertyAction;
  74 import sun.util.locale.BaseLocale;
  75 import sun.util.locale.LocaleObjectCache;
  76 import static sun.security.util.SecurityConstants.GET_CLASSLOADER_PERMISSION;
  77 
  78 
  79 /**
  80  *
  81  * Resource bundles contain locale-specific objects.  When your program needs a
  82  * locale-specific resource, a <code>String</code> for example, your program can
  83  * load it from the resource bundle that is appropriate for the current user's
  84  * locale. In this way, you can write program code that is largely independent
  85  * of the user's locale isolating most, if not all, of the locale-specific
  86  * information in resource bundles.
  87  *
  88  * <p>
  89  * This allows you to write programs that can:
  90  * <UL>
  91  * <LI> be easily localized, or translated, into different languages
  92  * <LI> handle multiple locales at once
  93  * <LI> be easily modified later to support even more locales
  94  * </UL>
  95  *
  96  * <P>
  97  * Resource bundles belong to families whose members share a common base
  98  * name, but whose names also have additional components that identify
  99  * their locales. For example, the base name of a family of resource
 100  * bundles might be "MyResources". The family should have a default
 101  * resource bundle which simply has the same name as its family -
 102  * "MyResources" - and will be used as the bundle of last resort if a
 103  * specific locale is not supported. The family can then provide as
 104  * many locale-specific members as needed, for example a German one
 105  * named "MyResources_de".
 106  *
 107  * <P>
 108  * Each resource bundle in a family contains the same items, but the items have
 109  * been translated for the locale represented by that resource bundle.
 110  * For example, both "MyResources" and "MyResources_de" may have a
 111  * <code>String</code> that's used on a button for canceling operations.
 112  * In "MyResources" the <code>String</code> may contain "Cancel" and in
 113  * "MyResources_de" it may contain "Abbrechen".
 114  *
 115  * <P>
 116  * If there are different resources for different countries, you
 117  * can make specializations: for example, "MyResources_de_CH" contains objects for
 118  * the German language (de) in Switzerland (CH). If you want to only
 119  * modify some of the resources
 120  * in the specialization, you can do so.
 121  *
 122  * <P>
 123  * When your program needs a locale-specific object, it loads
 124  * the <code>ResourceBundle</code> class using the
 125  * {@link #getBundle(java.lang.String, java.util.Locale) getBundle}
 126  * method:
 127  * <blockquote>
 128  * <pre>
 129  * ResourceBundle myResources =
 130  *      ResourceBundle.getBundle("MyResources", currentLocale);
 131  * </pre>
 132  * </blockquote>
 133  *
 134  * <P>
 135  * Resource bundles contain key/value pairs. The keys uniquely
 136  * identify a locale-specific object in the bundle. Here's an
 137  * example of a <code>ListResourceBundle</code> that contains
 138  * two key/value pairs:
 139  * <blockquote>
 140  * <pre>
 141  * public class MyResources extends ListResourceBundle {
 142  *     protected Object[][] getContents() {
 143  *         return new Object[][] {
 144  *             // LOCALIZE THE SECOND STRING OF EACH ARRAY (e.g., "OK")
 145  *             {"OkKey", "OK"},
 146  *             {"CancelKey", "Cancel"},
 147  *             // END OF MATERIAL TO LOCALIZE
 148  *        };
 149  *     }
 150  * }
 151  * </pre>
 152  * </blockquote>
 153  * Keys are always <code>String</code>s.
 154  * In this example, the keys are "OkKey" and "CancelKey".
 155  * In the above example, the values
 156  * are also <code>String</code>s--"OK" and "Cancel"--but
 157  * they don't have to be. The values can be any type of object.
 158  *
 159  * <P>
 160  * You retrieve an object from resource bundle using the appropriate
 161  * getter method. Because "OkKey" and "CancelKey"
 162  * are both strings, you would use <code>getString</code> to retrieve them:
 163  * <blockquote>
 164  * <pre>
 165  * button1 = new Button(myResources.getString("OkKey"));
 166  * button2 = new Button(myResources.getString("CancelKey"));
 167  * </pre>
 168  * </blockquote>
 169  * The getter methods all require the key as an argument and return
 170  * the object if found. If the object is not found, the getter method
 171  * throws a <code>MissingResourceException</code>.
 172  *
 173  * <P>
 174  * Besides <code>getString</code>, <code>ResourceBundle</code> also provides
 175  * a method for getting string arrays, <code>getStringArray</code>,
 176  * as well as a generic <code>getObject</code> method for any other
 177  * type of object. When using <code>getObject</code>, you'll
 178  * have to cast the result to the appropriate type. For example:
 179  * <blockquote>
 180  * <pre>
 181  * int[] myIntegers = (int[]) myResources.getObject("intList");
 182  * </pre>
 183  * </blockquote>
 184  *
 185  * <P>
 186  * The Java Platform provides two subclasses of <code>ResourceBundle</code>,
 187  * <code>ListResourceBundle</code> and <code>PropertyResourceBundle</code>,
 188  * that provide a fairly simple way to create resources.
 189  * As you saw briefly in a previous example, <code>ListResourceBundle</code>
 190  * manages its resource as a list of key/value pairs.
 191  * <code>PropertyResourceBundle</code> uses a properties file to manage
 192  * its resources.
 193  *
 194  * <p>
 195  * If <code>ListResourceBundle</code> or <code>PropertyResourceBundle</code>
 196  * do not suit your needs, you can write your own <code>ResourceBundle</code>
 197  * subclass.  Your subclasses must override two methods: <code>handleGetObject</code>
 198  * and <code>getKeys()</code>.
 199  *
 200  * <p>
 201  * The implementation of a {@code ResourceBundle} subclass must be thread-safe
 202  * if it's simultaneously used by multiple threads. The default implementations
 203  * of the non-abstract methods in this class, and the methods in the direct
 204  * known concrete subclasses {@code ListResourceBundle} and
 205  * {@code PropertyResourceBundle} are thread-safe.
 206  *
 207  * <h3><a id="resource-bundle-modules">Resource Bundles and Named Modules</a></h3>
 208  *
 209  * Resource bundles can be deployed in modules in the following ways:
 210  *
 211  * <h4>Resource bundles together with an application</h4>
 212  *
 213  * Resource bundles can be deployed together with an application in the same
 214  * module.  In that case, the resource bundles are loaded
 215  * by code in the module by calling the {@link #getBundle(String)}
 216  * or {@link #getBundle(String, Locale)} method.
 217  *
 218  * <h4><a id="service-providers">Resource bundles as service providers</a></h4>
 219  *
 220  * Resource bundles can be deployed in one or more <em>service provider modules</em>
 221  * and they can be located using {@link ServiceLoader}.
 222  * A {@linkplain ResourceBundleProvider service} interface or class must be
 223  * defined. The caller module declares that it uses the service, the service
 224  * provider modules declare that they provide implementations of the service.
 225  * Refer to {@link ResourceBundleProvider} for developing resource bundle
 226  * services and deploying resource bundle providers.
 227  * The module obtaining the resource bundle can be a resource bundle
 228  * provider itself; in which case this module only locates the resource bundle
 229  * via service provider mechanism.
 230  *
 231  * <p>A {@linkplain ResourceBundleProvider resource bundle provider} can
 232  * provide resource bundles in any format such XML which replaces the need
 233  * of {@link Control ResourceBundle.Control}.
 234  *
 235  * <h4><a id="other-modules">Resource bundles in other modules and class path</a></h4>
 236  *
 237  * Resource bundles in a named module may be <em>encapsulated</em> so that
 238  * it cannot be located by code in other modules.  Resource bundles
 239  * in unnamed modules and class path are open for any module to access.
 240  * Resource bundle follows the resource encapsulation rules as specified
 241  * in {@link Module#getResourceAsStream(String)}.
 242  *
 243  * <p>The {@code getBundle} factory methods with no {@code Control} parameter
 244  * locate and load resource bundles from
 245  * {@linkplain ResourceBundleProvider service providers}.
 246  * It may continue the search as if calling {@link Module#getResourceAsStream(String)}
 247  * to find the named resource from a given module and calling
 248  * {@link ClassLoader#getResourceAsStream(String)}; refer to
 249  * the specification of the {@code getBundle} method for details.
 250  * Only non-encapsulated resource bundles of "{@code java.class}"
 251  * or "{@code java.properties}" format are searched.
 252  *
 253  * <p>If the caller module is a
 254  * <a href="{@docRoot}/java.base/java/util/spi/ResourceBundleProvider.html#obtain-resource-bundle">
 255  * resource bundle provider</a>, it does not fall back to the
 256  * class loader search.
 257  *
 258  * <h4>Resource bundles in automatic modules</h4>
 259  *
 260  * A common format of resource bundles is in {@linkplain PropertyResourceBundle
 261  * .properties} file format.  Typically {@code .properties} resource bundles
 262  * are packaged in a JAR file.  Resource bundle only JAR file can be readily
 263  * deployed as an <a href="{@docRoot}/java.base/java/lang/module/ModuleFinder.html#automatic-modules">
 264  * automatic module</a>.  For example, if the JAR file contains the
 265  * entry "{@code p/q/Foo_ja.properties}" and no {@code .class} entry,
 266  * when resolved and defined as an automatic module, no package is derived
 267  * for this module.  This allows resource bundles in {@code .properties}
 268  * format packaged in one or more JAR files that may contain entries
 269  * in the same directory and can be resolved successfully as
 270  * automatic modules.
 271  *
 272  * <h3>ResourceBundle.Control</h3>
 273  *
 274  * The {@link ResourceBundle.Control} class provides information necessary
 275  * to perform the bundle loading process by the <code>getBundle</code>
 276  * factory methods that take a <code>ResourceBundle.Control</code>
 277  * instance. You can implement your own subclass in order to enable
 278  * non-standard resource bundle formats, change the search strategy, or
 279  * define caching parameters. Refer to the descriptions of the class and the
 280  * {@link #getBundle(String, Locale, ClassLoader, Control) getBundle}
 281  * factory method for details.
 282  *
 283  * <p> {@link ResourceBundle.Control} is designed for an application deployed
 284  * in an unnamed module, for example to support resource bundles in
 285  * non-standard formats or package localized resources in a non-traditional
 286  * convention. {@link ResourceBundleProvider} is the replacement for
 287  * {@code ResourceBundle.Control} when migrating to modules.
 288  * {@code UnsupportedOperationException} will be thrown when a factory
 289  * method that takes the {@code ResourceBundle.Control} parameter is called.
 290  *
 291  * <p><a id="modify_default_behavior">For the {@code getBundle} factory</a>
 292  * methods that take no {@link Control} instance, their <a
 293  * href="#default_behavior"> default behavior</a> of resource bundle loading
 294  * can be modified with custom {@link
 295  * ResourceBundleControlProvider} implementations.
 296  * If any of the
 297  * providers provides a {@link Control} for the given base name, that {@link
 298  * Control} will be used instead of the default {@link Control}. If there is
 299  * more than one service provider for supporting the same base name,
 300  * the first one returned from {@link ServiceLoader} will be used.
 301  * A custom {@link Control} implementation is ignored by named modules.
 302  *
 303  * <h3>Cache Management</h3>
 304  *
 305  * Resource bundle instances created by the <code>getBundle</code> factory
 306  * methods are cached by default, and the factory methods return the same
 307  * resource bundle instance multiple times if it has been
 308  * cached. <code>getBundle</code> clients may clear the cache, manage the
 309  * lifetime of cached resource bundle instances using time-to-live values,
 310  * or specify not to cache resource bundle instances. Refer to the
 311  * descriptions of the {@linkplain #getBundle(String, Locale, ClassLoader,
 312  * Control) <code>getBundle</code> factory method}, {@link
 313  * #clearCache(ClassLoader) clearCache}, {@link
 314  * Control#getTimeToLive(String, Locale)
 315  * ResourceBundle.Control.getTimeToLive}, and {@link
 316  * Control#needsReload(String, Locale, String, ClassLoader, ResourceBundle,
 317  * long) ResourceBundle.Control.needsReload} for details.
 318  *
 319  * <h3>Example</h3>
 320  *
 321  * The following is a very simple example of a <code>ResourceBundle</code>
 322  * subclass, <code>MyResources</code>, that manages two resources (for a larger number of
 323  * resources you would probably use a <code>Map</code>).
 324  * Notice that you don't need to supply a value if
 325  * a "parent-level" <code>ResourceBundle</code> handles the same
 326  * key with the same value (as for the okKey below).
 327  * <blockquote>
 328  * <pre>
 329  * // default (English language, United States)
 330  * public class MyResources extends ResourceBundle {
 331  *     public Object handleGetObject(String key) {
 332  *         if (key.equals("okKey")) return "Ok";
 333  *         if (key.equals("cancelKey")) return "Cancel";
 334  *         return null;
 335  *     }
 336  *
 337  *     public Enumeration&lt;String&gt; getKeys() {
 338  *         return Collections.enumeration(keySet());
 339  *     }
 340  *
 341  *     // Overrides handleKeySet() so that the getKeys() implementation
 342  *     // can rely on the keySet() value.
 343  *     protected Set&lt;String&gt; handleKeySet() {
 344  *         return new HashSet&lt;String&gt;(Arrays.asList("okKey", "cancelKey"));
 345  *     }
 346  * }
 347  *
 348  * // German language
 349  * public class MyResources_de extends MyResources {
 350  *     public Object handleGetObject(String key) {
 351  *         // don't need okKey, since parent level handles it.
 352  *         if (key.equals("cancelKey")) return "Abbrechen";
 353  *         return null;
 354  *     }
 355  *
 356  *     protected Set&lt;String&gt; handleKeySet() {
 357  *         return new HashSet&lt;String&gt;(Arrays.asList("cancelKey"));
 358  *     }
 359  * }
 360  * </pre>
 361  * </blockquote>
 362  * You do not have to restrict yourself to using a single family of
 363  * <code>ResourceBundle</code>s. For example, you could have a set of bundles for
 364  * exception messages, <code>ExceptionResources</code>
 365  * (<code>ExceptionResources_fr</code>, <code>ExceptionResources_de</code>, ...),
 366  * and one for widgets, <code>WidgetResource</code> (<code>WidgetResources_fr</code>,
 367  * <code>WidgetResources_de</code>, ...); breaking up the resources however you like.
 368  *
 369  * @see ListResourceBundle
 370  * @see PropertyResourceBundle
 371  * @see MissingResourceException
 372  * @see ResourceBundleProvider
 373  * @since 1.1
 374  * @revised 9
 375  * @spec JPMS
 376  */
 377 public abstract class ResourceBundle {
 378 
 379     /** initial size of the bundle cache */
 380     private static final int INITIAL_CACHE_SIZE = 32;
 381 
 382     static {
 383         SharedSecrets.setJavaUtilResourceBundleAccess(
 384             new JavaUtilResourceBundleAccess() {
 385                 @Override
 386                 public void setParent(ResourceBundle bundle,
 387                                       ResourceBundle parent) {
 388                     bundle.setParent(parent);
 389                 }
 390 
 391                 @Override
 392                 public ResourceBundle getParent(ResourceBundle bundle) {
 393                     return bundle.parent;
 394                 }
 395 
 396                 @Override
 397                 public void setLocale(ResourceBundle bundle, Locale locale) {
 398                     bundle.locale = locale;
 399                 }
 400 
 401                 @Override
 402                 public void setName(ResourceBundle bundle, String name) {
 403                     bundle.name = name;
 404                 }
 405 
 406                 @Override
 407                 public ResourceBundle getBundle(String baseName, Locale locale, Module module) {
 408                     // use the given module as the caller to bypass the access check
 409                     return getBundleImpl(module, module,
 410                                          baseName, locale,
 411                                          getDefaultControl(module, baseName));
 412                 }
 413 
 414                 @Override
 415                 public ResourceBundle newResourceBundle(Class<? extends ResourceBundle> bundleClass) {
 416                     return ResourceBundleProviderHelper.newResourceBundle(bundleClass);
 417                 }
 418             });
 419     }
 420 
 421     /** constant indicating that no resource bundle exists */
 422     private static final ResourceBundle NONEXISTENT_BUNDLE = new ResourceBundle() {
 423             public Enumeration<String> getKeys() { return null; }
 424             protected Object handleGetObject(String key) { return null; }
 425             public String toString() { return "NONEXISTENT_BUNDLE"; }
 426         };
 427 
 428 
 429     /**
 430      * The cache is a map from cache keys (with bundle base name, locale, and
 431      * class loader) to either a resource bundle or NONEXISTENT_BUNDLE wrapped by a
 432      * BundleReference.
 433      *
 434      * The cache is a ConcurrentMap, allowing the cache to be searched
 435      * concurrently by multiple threads.  This will also allow the cache keys
 436      * to be reclaimed along with the ClassLoaders they reference.
 437      *
 438      * This variable would be better named "cache", but we keep the old
 439      * name for compatibility with some workarounds for bug 4212439.
 440      */
 441     private static final ConcurrentMap<CacheKey, BundleReference> cacheList
 442         = new ConcurrentHashMap<>(INITIAL_CACHE_SIZE);
 443 
 444     /**
 445      * Queue for reference objects referring to class loaders or bundles.
 446      */
 447     private static final ReferenceQueue<Object> referenceQueue = new ReferenceQueue<>();
 448 
 449     /**
 450      * Returns the base name of this bundle, if known, or {@code null} if unknown.
 451      *
 452      * If not null, then this is the value of the {@code baseName} parameter
 453      * that was passed to the {@code ResourceBundle.getBundle(...)} method
 454      * when the resource bundle was loaded.
 455      *
 456      * @return The base name of the resource bundle, as provided to and expected
 457      * by the {@code ResourceBundle.getBundle(...)} methods.
 458      *
 459      * @see #getBundle(java.lang.String, java.util.Locale, java.lang.ClassLoader)
 460      *
 461      * @since 1.8
 462      */
 463     public String getBaseBundleName() {
 464         return name;
 465     }
 466 
 467     /**
 468      * The parent bundle of this bundle.
 469      * The parent bundle is searched by {@link #getObject getObject}
 470      * when this bundle does not contain a particular resource.
 471      */
 472     protected ResourceBundle parent = null;
 473 
 474     /**
 475      * The locale for this bundle.
 476      */
 477     private Locale locale = null;
 478 
 479     /**
 480      * The base bundle name for this bundle.
 481      */
 482     private String name;
 483 
 484     /**
 485      * The flag indicating this bundle has expired in the cache.
 486      */
 487     private volatile boolean expired;
 488 
 489     /**
 490      * The back link to the cache key. null if this bundle isn't in
 491      * the cache (yet) or has expired.
 492      */
 493     private volatile CacheKey cacheKey;
 494 
 495     /**
 496      * A Set of the keys contained only in this ResourceBundle.
 497      */
 498     private volatile Set<String> keySet;
 499 
 500     /**
 501      * Sole constructor.  (For invocation by subclass constructors, typically
 502      * implicit.)
 503      */
 504     public ResourceBundle() {
 505     }
 506 
 507     /**
 508      * Gets a string for the given key from this resource bundle or one of its parents.
 509      * Calling this method is equivalent to calling
 510      * <blockquote>
 511      * <code>(String) {@link #getObject(java.lang.String) getObject}(key)</code>.
 512      * </blockquote>
 513      *
 514      * @param key the key for the desired string
 515      * @exception NullPointerException if <code>key</code> is <code>null</code>
 516      * @exception MissingResourceException if no object for the given key can be found
 517      * @exception ClassCastException if the object found for the given key is not a string
 518      * @return the string for the given key
 519      */
 520     public final String getString(String key) {
 521         return (String) getObject(key);
 522     }
 523 
 524     /**
 525      * Gets a string array for the given key from this resource bundle or one of its parents.
 526      * Calling this method is equivalent to calling
 527      * <blockquote>
 528      * <code>(String[]) {@link #getObject(java.lang.String) getObject}(key)</code>.
 529      * </blockquote>
 530      *
 531      * @param key the key for the desired string array
 532      * @exception NullPointerException if <code>key</code> is <code>null</code>
 533      * @exception MissingResourceException if no object for the given key can be found
 534      * @exception ClassCastException if the object found for the given key is not a string array
 535      * @return the string array for the given key
 536      */
 537     public final String[] getStringArray(String key) {
 538         return (String[]) getObject(key);
 539     }
 540 
 541     /**
 542      * Gets an object for the given key from this resource bundle or one of its parents.
 543      * This method first tries to obtain the object from this resource bundle using
 544      * {@link #handleGetObject(java.lang.String) handleGetObject}.
 545      * If not successful, and the parent resource bundle is not null,
 546      * it calls the parent's <code>getObject</code> method.
 547      * If still not successful, it throws a MissingResourceException.
 548      *
 549      * @param key the key for the desired object
 550      * @exception NullPointerException if <code>key</code> is <code>null</code>
 551      * @exception MissingResourceException if no object for the given key can be found
 552      * @return the object for the given key
 553      */
 554     public final Object getObject(String key) {
 555         Object obj = handleGetObject(key);
 556         if (obj == null) {
 557             if (parent != null) {
 558                 obj = parent.getObject(key);
 559             }
 560             if (obj == null) {
 561                 throw new MissingResourceException("Can't find resource for bundle "
 562                                                    +this.getClass().getName()
 563                                                    +", key "+key,
 564                                                    this.getClass().getName(),
 565                                                    key);
 566             }
 567         }
 568         return obj;
 569     }
 570 
 571     /**
 572      * Returns the locale of this resource bundle. This method can be used after a
 573      * call to getBundle() to determine whether the resource bundle returned really
 574      * corresponds to the requested locale or is a fallback.
 575      *
 576      * @return the locale of this resource bundle
 577      */
 578     public Locale getLocale() {
 579         return locale;
 580     }
 581 
 582     private static ClassLoader getLoader(Module module) {
 583         PrivilegedAction<ClassLoader> pa = module::getClassLoader;
 584         return AccessController.doPrivileged(pa);
 585     }
 586 
 587     /**
 588      * @param module a non-null-screened module form the {@link CacheKey#getModule()}.
 589      * @return the ClassLoader to use in {@link Control#needsReload}
 590      *         and {@link Control#newBundle}
 591      */
 592     private static ClassLoader getLoaderForControl(Module module) {
 593         ClassLoader loader = getLoader(module);
 594         return loader == null ? ClassLoader.getPlatformClassLoader() : loader;
 595     }
 596 
 597     /**
 598      * Sets the parent bundle of this bundle.
 599      * The parent bundle is searched by {@link #getObject getObject}
 600      * when this bundle does not contain a particular resource.
 601      *
 602      * @param parent this bundle's parent bundle.
 603      */
 604     protected void setParent(ResourceBundle parent) {
 605         assert parent != NONEXISTENT_BUNDLE;
 606         this.parent = parent;
 607     }
 608 
 609     /**
 610      * Key used for cached resource bundles.  The key checks the base
 611      * name, the locale, the bundle module, and the caller module
 612      * to determine if the resource is a match to the requested one.
 613      * The base name, the locale and both modules must have a non-null value.
 614      */
 615     private static final class CacheKey {
 616         // These four are the actual keys for lookup in Map.
 617         private final String name;
 618         private volatile Locale locale;
 619         private final KeyElementReference<Module> moduleRef;
 620         private final KeyElementReference<Module> callerRef;
 621         // this is the part of hashCode that pertains to module and callerModule
 622         // which can be GCed..
 623         private final int modulesHash;
 624 
 625         // bundle format which is necessary for calling
 626         // Control.needsReload().
 627         private volatile String format;
 628 
 629         // These time values are in CacheKey so that NONEXISTENT_BUNDLE
 630         // doesn't need to be cloned for caching.
 631 
 632         // The time when the bundle has been loaded
 633         private volatile long loadTime;
 634 
 635         // The time when the bundle expires in the cache, or either
 636         // Control.TTL_DONT_CACHE or Control.TTL_NO_EXPIRATION_CONTROL.
 637         private volatile long expirationTime;
 638 
 639         // Placeholder for an error report by a Throwable
 640         private volatile Throwable cause;
 641 
 642         // ResourceBundleProviders for loading ResourceBundles
 643         private volatile ServiceLoader<ResourceBundleProvider> providers;
 644         private volatile boolean providersChecked;
 645 
 646         // Boolean.TRUE if the factory method caller provides a ResourceBundleProvier.
 647         private volatile Boolean callerHasProvider;
 648 
 649         CacheKey(String baseName, Locale locale, Module module, Module caller) {
 650             Objects.requireNonNull(module);
 651             Objects.requireNonNull(caller);
 652 
 653             this.name = baseName;
 654             this.locale = locale;
 655             this.moduleRef = new KeyElementReference<>(module, referenceQueue, this);
 656             this.callerRef = new KeyElementReference<>(caller, referenceQueue, this);
 657             this.modulesHash = module.hashCode() ^ caller.hashCode();
 658         }
 659 
 660         CacheKey(CacheKey src) {
 661             // Create References to src's modules
 662             this.moduleRef = new KeyElementReference<>(
 663                 Objects.requireNonNull(src.getModule()), referenceQueue, this);
 664             this.callerRef = new KeyElementReference<>(
 665                 Objects.requireNonNull(src.getCallerModule()), referenceQueue, this);
 666             // Copy fields from src. ResourceBundleProviders related fields
 667             // and "cause" should not be copied.
 668             this.name = src.name;
 669             this.locale = src.locale;
 670             this.modulesHash = src.modulesHash;
 671             this.format = src.format;
 672             this.loadTime = src.loadTime;
 673             this.expirationTime = src.expirationTime;
 674         }
 675 
 676         String getName() {
 677             return name;
 678         }
 679 
 680         Locale getLocale() {
 681             return locale;
 682         }
 683 
 684         CacheKey setLocale(Locale locale) {
 685             this.locale = locale;
 686             return this;
 687         }
 688 
 689         Module getModule() {
 690             return moduleRef.get();
 691         }
 692 
 693         Module getCallerModule() {
 694             return callerRef.get();
 695         }
 696 
 697         ServiceLoader<ResourceBundleProvider> getProviders() {
 698             if (!providersChecked) {
 699                 providers = getServiceLoader(getModule(), name);
 700                 providersChecked = true;
 701             }
 702             return providers;
 703         }
 704 
 705         boolean hasProviders() {
 706             return getProviders() != null;
 707         }
 708 
 709         boolean callerHasProvider() {
 710             return callerHasProvider == Boolean.TRUE;
 711         }
 712 
 713         @Override
 714         public boolean equals(Object other) {
 715             if (this == other) {
 716                 return true;
 717             }
 718             try {
 719                 final CacheKey otherEntry = (CacheKey)other;
 720                 //quick check to see if they are not equal
 721                 if (modulesHash != otherEntry.modulesHash) {
 722                     return false;
 723                 }
 724                 //are the names the same?
 725                 if (!name.equals(otherEntry.name)) {
 726                     return false;
 727                 }
 728                 // are the locales the same?
 729                 if (!locale.equals(otherEntry.locale)) {
 730                     return false;
 731                 }
 732                 // are modules and callerModules the same and non-null?
 733                 Module module = getModule();
 734                 Module caller = getCallerModule();
 735                 return ((module != null) && (module.equals(otherEntry.getModule())) &&
 736                         (caller != null) && (caller.equals(otherEntry.getCallerModule())));
 737             } catch (NullPointerException | ClassCastException e) {
 738             }
 739             return false;
 740         }
 741 
 742         @Override
 743         public int hashCode() {
 744             return (name.hashCode() << 3) ^ locale.hashCode() ^ modulesHash;
 745         }
 746 
 747         String getFormat() {
 748             return format;
 749         }
 750 
 751         void setFormat(String format) {
 752             this.format = format;
 753         }
 754 
 755         private void setCause(Throwable cause) {
 756             if (this.cause == null) {
 757                 this.cause = cause;
 758             } else {
 759                 // Override the cause if the previous one is
 760                 // ClassNotFoundException.
 761                 if (this.cause instanceof ClassNotFoundException) {
 762                     this.cause = cause;
 763                 }
 764             }
 765         }
 766 
 767         private Throwable getCause() {
 768             return cause;
 769         }
 770 
 771         @Override
 772         public String toString() {
 773             String l = locale.toString();
 774             if (l.isEmpty()) {
 775                 if (!locale.getVariant().isEmpty()) {
 776                     l = "__" + locale.getVariant();
 777                 } else {
 778                     l = "\"\"";
 779                 }
 780             }
 781             return "CacheKey[" + name +
 782                    ", locale=" + l +
 783                    ", module=" + getModule() +
 784                    ", callerModule=" + getCallerModule() +
 785                    ", format=" + format +
 786                    "]";
 787         }
 788     }
 789 
 790     /**
 791      * The common interface to get a CacheKey in LoaderReference and
 792      * BundleReference.
 793      */
 794     private static interface CacheKeyReference {
 795         public CacheKey getCacheKey();
 796     }
 797 
 798     /**
 799      * References to a CacheKey element as a WeakReference so that it can be
 800      * garbage collected when nobody else is using it.
 801      */
 802     private static class KeyElementReference<T> extends WeakReference<T>
 803                                                 implements CacheKeyReference {
 804         private final CacheKey cacheKey;
 805 
 806         KeyElementReference(T referent, ReferenceQueue<Object> q, CacheKey key) {
 807             super(referent, q);
 808             cacheKey = key;
 809         }
 810 
 811         @Override
 812         public CacheKey getCacheKey() {
 813             return cacheKey;
 814         }
 815     }
 816 
 817     /**
 818      * References to bundles are soft references so that they can be garbage
 819      * collected when they have no hard references.
 820      */
 821     private static class BundleReference extends SoftReference<ResourceBundle>
 822                                          implements CacheKeyReference {
 823         private final CacheKey cacheKey;
 824 
 825         BundleReference(ResourceBundle referent, ReferenceQueue<Object> q, CacheKey key) {
 826             super(referent, q);
 827             cacheKey = key;
 828         }
 829 
 830         @Override
 831         public CacheKey getCacheKey() {
 832             return cacheKey;
 833         }
 834     }
 835 
 836     /**
 837      * Gets a resource bundle using the specified base name, the default locale,
 838      * and the caller module. Calling this method is equivalent to calling
 839      * <blockquote>
 840      * <code>getBundle(baseName, Locale.getDefault(), callerModule)</code>,
 841      * </blockquote>
 842      *
 843      * @param baseName the base name of the resource bundle, a fully qualified class name
 844      * @exception java.lang.NullPointerException
 845      *     if <code>baseName</code> is <code>null</code>
 846      * @exception MissingResourceException
 847      *     if no resource bundle for the specified base name can be found
 848      * @return a resource bundle for the given base name and the default locale
 849      *
 850      * @see <a href="#default_behavior">Resource Bundle Search and Loading Strategy</a>
 851      * @see <a href="#resource-bundle-modules">Resource Bundles and Named Modules</a>
 852      */
 853     @CallerSensitive
 854     public static final ResourceBundle getBundle(String baseName)
 855     {
 856         Class<?> caller = Reflection.getCallerClass();
 857         return getBundleImpl(baseName, Locale.getDefault(),
 858                              caller, getDefaultControl(caller, baseName));
 859     }
 860 
 861     /**
 862      * Returns a resource bundle using the specified base name, the
 863      * default locale and the specified control. Calling this method
 864      * is equivalent to calling
 865      * <pre>
 866      * getBundle(baseName, Locale.getDefault(),
 867      *           this.getClass().getClassLoader(), control),
 868      * </pre>
 869      * except that <code>getClassLoader()</code> is run with the security
 870      * privileges of <code>ResourceBundle</code>.  See {@link
 871      * #getBundle(String, Locale, ClassLoader, Control) getBundle} for the
 872      * complete description of the resource bundle loading process with a
 873      * <code>ResourceBundle.Control</code>.
 874      *
 875      * @param baseName
 876      *        the base name of the resource bundle, a fully qualified class
 877      *        name
 878      * @param control
 879      *        the control which gives information for the resource bundle
 880      *        loading process
 881      * @return a resource bundle for the given base name and the default locale
 882      * @throws NullPointerException
 883      *         if <code>baseName</code> or <code>control</code> is
 884      *         <code>null</code>
 885      * @throws MissingResourceException
 886      *         if no resource bundle for the specified base name can be found
 887      * @throws IllegalArgumentException
 888      *         if the given <code>control</code> doesn't perform properly
 889      *         (e.g., <code>control.getCandidateLocales</code> returns null.)
 890      *         Note that validation of <code>control</code> is performed as
 891      *         needed.
 892      * @throws UnsupportedOperationException
 893      *         if this method is called in a named module
 894      * @since 1.6
 895      * @revised 9
 896      * @spec JPMS
 897      */
 898     @CallerSensitive
 899     public static final ResourceBundle getBundle(String baseName,
 900                                                  Control control) {
 901         Class<?> caller = Reflection.getCallerClass();
 902         Locale targetLocale = Locale.getDefault();
 903         checkNamedModule(caller);
 904         return getBundleImpl(baseName, targetLocale, caller, control);
 905     }
 906 
 907     /**
 908      * Gets a resource bundle using the specified base name and locale,
 909      * and the caller module. Calling this method is equivalent to calling
 910      * <blockquote>
 911      * <code>getBundle(baseName, locale, callerModule)</code>,
 912      * </blockquote>
 913      *
 914      * @param baseName
 915      *        the base name of the resource bundle, a fully qualified class name
 916      * @param locale
 917      *        the locale for which a resource bundle is desired
 918      * @exception NullPointerException
 919      *        if <code>baseName</code> or <code>locale</code> is <code>null</code>
 920      * @exception MissingResourceException
 921      *        if no resource bundle for the specified base name can be found
 922      * @return a resource bundle for the given base name and locale
 923      *
 924      * @see <a href="#default_behavior">Resource Bundle Search and Loading Strategy</a>
 925      * @see <a href="#resource-bundle-modules">Resource Bundles and Named Modules</a>
 926      */
 927     @CallerSensitive
 928     public static final ResourceBundle getBundle(String baseName,
 929                                                  Locale locale)
 930     {
 931         Class<?> caller = Reflection.getCallerClass();
 932         return getBundleImpl(baseName, locale,
 933                              caller, getDefaultControl(caller, baseName));
 934     }
 935 
 936     /**
 937      * Gets a resource bundle using the specified base name and the default locale
 938      * on behalf of the specified module. This method is equivalent to calling
 939      * <blockquote>
 940      * <code>getBundle(baseName, Locale.getDefault(), module)</code>
 941      * </blockquote>
 942      *
 943      * @param baseName the base name of the resource bundle,
 944      *                 a fully qualified class name
 945      * @param module   the module for which the resource bundle is searched
 946      * @throws NullPointerException
 947      *         if {@code baseName} or {@code module} is {@code null}
 948      * @throws SecurityException
 949      *         if a security manager exists and the caller is not the specified
 950      *         module and doesn't have {@code RuntimePermission("getClassLoader")}
 951      * @throws MissingResourceException
 952      *         if no resource bundle for the specified base name can be found in the
 953      *         specified module
 954      * @return a resource bundle for the given base name and the default locale
 955      * @since 9
 956      * @spec JPMS
 957      * @see ResourceBundleProvider
 958      * @see <a href="#default_behavior">Resource Bundle Search and Loading Strategy</a>
 959      * @see <a href="#resource-bundle-modules">Resource Bundles and Named Modules</a>
 960      */
 961     @CallerSensitive
 962     public static ResourceBundle getBundle(String baseName, Module module) {
 963         return getBundleFromModule(Reflection.getCallerClass(), module, baseName,
 964                                    Locale.getDefault(),
 965                                    getDefaultControl(module, baseName));
 966     }
 967 
 968     /**
 969      * Gets a resource bundle using the specified base name and locale
 970      * on behalf of the specified module.
 971      *
 972      * <p> Resource bundles in named modules may be encapsulated.  When
 973      * the resource bundle is loaded from a
 974      * {@linkplain ResourceBundleProvider service provider}, the caller module
 975      * must have an appropriate <i>uses</i> clause in its <i>module descriptor</i>
 976      * to declare that the module uses of {@link ResourceBundleProvider}
 977      * for the named resource bundle.
 978      * Otherwise, it will load the resource bundles that are local in the
 979      * given module as if calling {@link Module#getResourceAsStream(String)}
 980      * or that are visible to the class loader of the given module
 981      * as if calling {@link ClassLoader#getResourceAsStream(String)}.
 982      * When the resource bundle is loaded from the specified module, it is
 983      * subject to the encapsulation rules specified by
 984      * {@link Module#getResourceAsStream Module.getResourceAsStream}.
 985      *
 986      * <p>
 987      * If the given {@code module} is an unnamed module, then this method is
 988      * equivalent to calling {@link #getBundle(String, Locale, ClassLoader)
 989      * getBundle(baseName, targetLocale, module.getClassLoader()} to load
 990      * resource bundles that are visible to the class loader of the given
 991      * unnamed module. Custom {@link java.util.spi.ResourceBundleControlProvider}
 992      * implementations, if present, will only be invoked if the specified
 993      * module is an unnamed module.
 994      *
 995      * @param baseName the base name of the resource bundle,
 996      *                 a fully qualified class name
 997      * @param targetLocale the locale for which a resource bundle is desired
 998      * @param module   the module for which the resource bundle is searched
 999      * @throws NullPointerException
1000      *         if {@code baseName}, {@code targetLocale}, or {@code module} is
1001      *         {@code null}
1002      * @throws SecurityException
1003      *         if a security manager exists and the caller is not the specified
1004      *         module and doesn't have {@code RuntimePermission("getClassLoader")}
1005      * @throws MissingResourceException
1006      *         if no resource bundle for the specified base name and locale can
1007      *         be found in the specified {@code module}
1008      * @return a resource bundle for the given base name and locale in the module
1009      * @since 9
1010      * @spec JPMS
1011      * @see <a href="#default_behavior">Resource Bundle Search and Loading Strategy</a>
1012      * @see <a href="#resource-bundle-modules">Resource Bundles and Named Modules</a>
1013      */
1014     @CallerSensitive
1015     public static ResourceBundle getBundle(String baseName, Locale targetLocale, Module module) {
1016         return getBundleFromModule(Reflection.getCallerClass(), module, baseName, targetLocale,
1017                                    getDefaultControl(module, baseName));
1018     }
1019 
1020     /**
1021      * Returns a resource bundle using the specified base name, target
1022      * locale and control, and the caller's class loader. Calling this
1023      * method is equivalent to calling
1024      * <pre>
1025      * getBundle(baseName, targetLocale, this.getClass().getClassLoader(),
1026      *           control),
1027      * </pre>
1028      * except that <code>getClassLoader()</code> is run with the security
1029      * privileges of <code>ResourceBundle</code>.  See {@link
1030      * #getBundle(String, Locale, ClassLoader, Control) getBundle} for the
1031      * complete description of the resource bundle loading process with a
1032      * <code>ResourceBundle.Control</code>.
1033      *
1034      * @param baseName
1035      *        the base name of the resource bundle, a fully qualified
1036      *        class name
1037      * @param targetLocale
1038      *        the locale for which a resource bundle is desired
1039      * @param control
1040      *        the control which gives information for the resource
1041      *        bundle loading process
1042      * @return a resource bundle for the given base name and a
1043      *         <code>Locale</code> in <code>locales</code>
1044      * @throws NullPointerException
1045      *         if <code>baseName</code>, <code>locales</code> or
1046      *         <code>control</code> is <code>null</code>
1047      * @throws MissingResourceException
1048      *         if no resource bundle for the specified base name in any
1049      *         of the <code>locales</code> can be found.
1050      * @throws IllegalArgumentException
1051      *         if the given <code>control</code> doesn't perform properly
1052      *         (e.g., <code>control.getCandidateLocales</code> returns null.)
1053      *         Note that validation of <code>control</code> is performed as
1054      *         needed.
1055      * @throws UnsupportedOperationException
1056      *         if this method is called in a named module
1057      * @since 1.6
1058      * @revised 9
1059      * @spec JPMS
1060      */
1061     @CallerSensitive
1062     public static final ResourceBundle getBundle(String baseName, Locale targetLocale,
1063                                                  Control control) {
1064         Class<?> caller = Reflection.getCallerClass();
1065         checkNamedModule(caller);
1066         return getBundleImpl(baseName, targetLocale, caller, control);
1067     }
1068 
1069     /**
1070      * Gets a resource bundle using the specified base name, locale, and class
1071      * loader.
1072      *
1073      * <p>When this method is called from a named module and the given
1074      * loader is the class loader of the caller module, this is equivalent
1075      * to calling:
1076      * <blockquote><pre>
1077      * getBundle(baseName, targetLocale, callerModule)
1078      * </pre></blockquote>
1079      *
1080      * otherwise, this is equivalent to calling:
1081      * <blockquote><pre>
1082      * getBundle(baseName, targetLocale, loader, control)
1083      * </pre></blockquote>
1084      * where {@code control} is the default instance of {@link Control} unless
1085      * a {@code Control} instance is provided by
1086      * {@link ResourceBundleControlProvider} SPI.  Refer to the
1087      * description of <a href="#modify_default_behavior">modifying the default
1088      * behavior</a>. The following describes the default behavior.
1089      *
1090      * <p>
1091      * <b><a id="default_behavior">Resource Bundle Search and Loading Strategy</a></b>
1092      *
1093      * <p><code>getBundle</code> uses the base name, the specified locale, and
1094      * the default locale (obtained from {@link java.util.Locale#getDefault()
1095      * Locale.getDefault}) to generate a sequence of <a
1096      * id="candidates"><em>candidate bundle names</em></a>.  If the specified
1097      * locale's language, script, country, and variant are all empty strings,
1098      * then the base name is the only candidate bundle name.  Otherwise, a list
1099      * of candidate locales is generated from the attribute values of the
1100      * specified locale (language, script, country and variant) and appended to
1101      * the base name.  Typically, this will look like the following:
1102      *
1103      * <pre>
1104      *     baseName + "_" + language + "_" + script + "_" + country + "_" + variant
1105      *     baseName + "_" + language + "_" + script + "_" + country
1106      *     baseName + "_" + language + "_" + script
1107      *     baseName + "_" + language + "_" + country + "_" + variant
1108      *     baseName + "_" + language + "_" + country
1109      *     baseName + "_" + language
1110      * </pre>
1111      *
1112      * <p>Candidate bundle names where the final component is an empty string
1113      * are omitted, along with the underscore.  For example, if country is an
1114      * empty string, the second and the fifth candidate bundle names above
1115      * would be omitted.  Also, if script is an empty string, the candidate names
1116      * including script are omitted.  For example, a locale with language "de"
1117      * and variant "JAVA" will produce candidate names with base name
1118      * "MyResource" below.
1119      *
1120      * <pre>
1121      *     MyResource_de__JAVA
1122      *     MyResource_de
1123      * </pre>
1124      *
1125      * In the case that the variant contains one or more underscores ('_'), a
1126      * sequence of bundle names generated by truncating the last underscore and
1127      * the part following it is inserted after a candidate bundle name with the
1128      * original variant.  For example, for a locale with language "en", script
1129      * "Latn, country "US" and variant "WINDOWS_VISTA", and bundle base name
1130      * "MyResource", the list of candidate bundle names below is generated:
1131      *
1132      * <pre>
1133      * MyResource_en_Latn_US_WINDOWS_VISTA
1134      * MyResource_en_Latn_US_WINDOWS
1135      * MyResource_en_Latn_US
1136      * MyResource_en_Latn
1137      * MyResource_en_US_WINDOWS_VISTA
1138      * MyResource_en_US_WINDOWS
1139      * MyResource_en_US
1140      * MyResource_en
1141      * </pre>
1142      *
1143      * <blockquote><b>Note:</b> For some <code>Locale</code>s, the list of
1144      * candidate bundle names contains extra names, or the order of bundle names
1145      * is slightly modified.  See the description of the default implementation
1146      * of {@link Control#getCandidateLocales(String, Locale)
1147      * getCandidateLocales} for details.</blockquote>
1148      *
1149      * <p><code>getBundle</code> then iterates over the candidate bundle names
1150      * to find the first one for which it can <em>instantiate</em> an actual
1151      * resource bundle. It uses the default controls' {@link Control#getFormats
1152      * getFormats} method, which generates two bundle names for each generated
1153      * name, the first a class name and the second a properties file name. For
1154      * each candidate bundle name, it attempts to create a resource bundle:
1155      *
1156      * <ul><li>First, it attempts to load a class using the generated class name.
1157      * If such a class can be found and loaded using the specified class
1158      * loader, is assignment compatible with ResourceBundle, is accessible from
1159      * ResourceBundle, and can be instantiated, <code>getBundle</code> creates a
1160      * new instance of this class and uses it as the <em>result resource
1161      * bundle</em>.
1162      *
1163      * <li>Otherwise, <code>getBundle</code> attempts to locate a property
1164      * resource file using the generated properties file name.  It generates a
1165      * path name from the candidate bundle name by replacing all "." characters
1166      * with "/" and appending the string ".properties".  It attempts to find a
1167      * "resource" with this name using {@link
1168      * java.lang.ClassLoader#getResource(java.lang.String)
1169      * ClassLoader.getResource}.  (Note that a "resource" in the sense of
1170      * <code>getResource</code> has nothing to do with the contents of a
1171      * resource bundle, it is just a container of data, such as a file.)  If it
1172      * finds a "resource", it attempts to create a new {@link
1173      * PropertyResourceBundle} instance from its contents.  If successful, this
1174      * instance becomes the <em>result resource bundle</em>.  </ul>
1175      *
1176      * <p>This continues until a result resource bundle is instantiated or the
1177      * list of candidate bundle names is exhausted.  If no matching resource
1178      * bundle is found, the default control's {@link Control#getFallbackLocale
1179      * getFallbackLocale} method is called, which returns the current default
1180      * locale.  A new sequence of candidate locale names is generated using this
1181      * locale and searched again, as above.
1182      *
1183      * <p>If still no result bundle is found, the base name alone is looked up. If
1184      * this still fails, a <code>MissingResourceException</code> is thrown.
1185      *
1186      * <p><a id="parent_chain"> Once a result resource bundle has been found,
1187      * its <em>parent chain</em> is instantiated</a>.  If the result bundle already
1188      * has a parent (perhaps because it was returned from a cache) the chain is
1189      * complete.
1190      *
1191      * <p>Otherwise, <code>getBundle</code> examines the remainder of the
1192      * candidate locale list that was used during the pass that generated the
1193      * result resource bundle.  (As before, candidate bundle names where the
1194      * final component is an empty string are omitted.)  When it comes to the
1195      * end of the candidate list, it tries the plain bundle name.  With each of the
1196      * candidate bundle names it attempts to instantiate a resource bundle (first
1197      * looking for a class and then a properties file, as described above).
1198      *
1199      * <p>Whenever it succeeds, it calls the previously instantiated resource
1200      * bundle's {@link #setParent(java.util.ResourceBundle) setParent} method
1201      * with the new resource bundle.  This continues until the list of names
1202      * is exhausted or the current bundle already has a non-null parent.
1203      *
1204      * <p>Once the parent chain is complete, the bundle is returned.
1205      *
1206      * <p><b>Note:</b> <code>getBundle</code> caches instantiated resource
1207      * bundles and might return the same resource bundle instance multiple times.
1208      *
1209      * <p><b>Note:</b>The <code>baseName</code> argument should be a fully
1210      * qualified class name. However, for compatibility with earlier versions,
1211      * Java SE Runtime Environments do not verify this, and so it is
1212      * possible to access <code>PropertyResourceBundle</code>s by specifying a
1213      * path name (using "/") instead of a fully qualified class name (using
1214      * ".").
1215      *
1216      * <p><a id="default_behavior_example">
1217      * <strong>Example:</strong></a>
1218      * <p>
1219      * The following class and property files are provided:
1220      * <ul>
1221      *     <li>MyResources.class
1222      *     <li>MyResources.properties
1223      *     <li>MyResources_fr.properties
1224      *     <li>MyResources_fr_CH.class
1225      *     <li>MyResources_fr_CH.properties
1226      *     <li>MyResources_en.properties
1227      *     <li>MyResources_es_ES.class
1228      * </ul>
1229      *
1230      * The contents of all files are valid (that is, public non-abstract
1231      * subclasses of <code>ResourceBundle</code> for the ".class" files,
1232      * syntactically correct ".properties" files).  The default locale is
1233      * <code>Locale("en", "GB")</code>.
1234      *
1235      * <p>Calling <code>getBundle</code> with the locale arguments below will
1236      * instantiate resource bundles as follows:
1237      *
1238      * <table class="striped">
1239      * <caption style="display:none">getBundle() locale to resource bundle mapping</caption>
1240      * <thead>
1241      * <tr><th scope="col">Locale</th><th scope="col">Resource bundle</th></tr>
1242      * </thead>
1243      * <tbody>
1244      * <tr><th scope="row">Locale("fr", "CH")</th><td>MyResources_fr_CH.class, parent MyResources_fr.properties, parent MyResources.class</td></tr>
1245      * <tr><th scope="row">Locale("fr", "FR")</th><td>MyResources_fr.properties, parent MyResources.class</td></tr>
1246      * <tr><th scope="row">Locale("de", "DE")</th><td>MyResources_en.properties, parent MyResources.class</td></tr>
1247      * <tr><th scope="row">Locale("en", "US")</th><td>MyResources_en.properties, parent MyResources.class</td></tr>
1248      * <tr><th scope="row">Locale("es", "ES")</th><td>MyResources_es_ES.class, parent MyResources.class</td></tr>
1249      * </tbody>
1250      * </table>
1251      *
1252      * <p>The file MyResources_fr_CH.properties is never used because it is
1253      * hidden by the MyResources_fr_CH.class. Likewise, MyResources.properties
1254      * is also hidden by MyResources.class.
1255      *
1256      * @apiNote If the caller module is a named module and the given
1257      * {@code loader} is the caller module's class loader, this method is
1258      * equivalent to {@code getBundle(baseName, locale)}; otherwise, it may not
1259      * find resource bundles from named modules.
1260      * Use {@link #getBundle(String, Locale, Module)} to load resource bundles
1261      * on behalf on a specific module instead.
1262      *
1263      * @param baseName the base name of the resource bundle, a fully qualified class name
1264      * @param locale the locale for which a resource bundle is desired
1265      * @param loader the class loader from which to load the resource bundle
1266      * @return a resource bundle for the given base name and locale
1267      * @exception java.lang.NullPointerException
1268      *        if <code>baseName</code>, <code>locale</code>, or <code>loader</code> is <code>null</code>
1269      * @exception MissingResourceException
1270      *        if no resource bundle for the specified base name can be found
1271      * @since 1.2
1272      * @revised 9
1273      * @spec JPMS
1274      * @see <a href="#resource-bundle-modules">Resource Bundles and Named Modules</a>
1275      */
1276     @CallerSensitive
1277     public static ResourceBundle getBundle(String baseName, Locale locale,
1278                                            ClassLoader loader)
1279     {
1280         if (loader == null) {
1281             throw new NullPointerException();
1282         }
1283         Class<?> caller = Reflection.getCallerClass();
1284         return getBundleImpl(baseName, locale, caller, loader, getDefaultControl(caller, baseName));
1285     }
1286 
1287     /**
1288      * Returns a resource bundle using the specified base name, target
1289      * locale, class loader and control. Unlike the {@link
1290      * #getBundle(String, Locale, ClassLoader) getBundle}
1291      * factory methods with no {@code control} argument, the given
1292      * <code>control</code> specifies how to locate and instantiate resource
1293      * bundles. Conceptually, the bundle loading process with the given
1294      * <code>control</code> is performed in the following steps.
1295      *
1296      * <ol>
1297      * <li>This factory method looks up the resource bundle in the cache for
1298      * the specified <code>baseName</code>, <code>targetLocale</code> and
1299      * <code>loader</code>.  If the requested resource bundle instance is
1300      * found in the cache and the time-to-live periods of the instance and
1301      * all of its parent instances have not expired, the instance is returned
1302      * to the caller. Otherwise, this factory method proceeds with the
1303      * loading process below.</li>
1304      *
1305      * <li>The {@link ResourceBundle.Control#getFormats(String)
1306      * control.getFormats} method is called to get resource bundle formats
1307      * to produce bundle or resource names. The strings
1308      * <code>"java.class"</code> and <code>"java.properties"</code>
1309      * designate class-based and {@linkplain PropertyResourceBundle
1310      * property}-based resource bundles, respectively. Other strings
1311      * starting with <code>"java."</code> are reserved for future extensions
1312      * and must not be used for application-defined formats. Other strings
1313      * designate application-defined formats.</li>
1314      *
1315      * <li>The {@link ResourceBundle.Control#getCandidateLocales(String,
1316      * Locale) control.getCandidateLocales} method is called with the target
1317      * locale to get a list of <em>candidate <code>Locale</code>s</em> for
1318      * which resource bundles are searched.</li>
1319      *
1320      * <li>The {@link ResourceBundle.Control#newBundle(String, Locale,
1321      * String, ClassLoader, boolean) control.newBundle} method is called to
1322      * instantiate a <code>ResourceBundle</code> for the base bundle name, a
1323      * candidate locale, and a format. (Refer to the note on the cache
1324      * lookup below.) This step is iterated over all combinations of the
1325      * candidate locales and formats until the <code>newBundle</code> method
1326      * returns a <code>ResourceBundle</code> instance or the iteration has
1327      * used up all the combinations. For example, if the candidate locales
1328      * are <code>Locale("de", "DE")</code>, <code>Locale("de")</code> and
1329      * <code>Locale("")</code> and the formats are <code>"java.class"</code>
1330      * and <code>"java.properties"</code>, then the following is the
1331      * sequence of locale-format combinations to be used to call
1332      * <code>control.newBundle</code>.
1333      *
1334      * <table class=striped style="width: 50%; text-align: left; margin-left: 40px;">
1335      * <caption style="display:none">locale-format combinations for newBundle</caption>
1336      * <thead>
1337      * <tr>
1338      * <th scope="col">Index</th>
1339      * <th scope="col"><code>Locale</code></th>
1340      * <th scope="col"><code>format</code></th>
1341      * </tr>
1342      * </thead>
1343      * <tbody>
1344      * <tr>
1345      * <th scope="row">1</th>
1346      * <td><code>Locale("de", "DE")</code></td>
1347      * <td><code>java.class</code></td>
1348      * </tr>
1349      * <tr>
1350      * <th scope="row">2</th>
1351      * <td><code>Locale("de", "DE")</code></td>
1352      * <td><code>java.properties</code></td>
1353      * </tr>
1354      * <tr>
1355      * <th scope="row">3</th>
1356      * <td><code>Locale("de")</code></td>
1357      * <td><code>java.class</code></td>
1358      * </tr>
1359      * <tr>
1360      * <th scope="row">4</th>
1361      * <td><code>Locale("de")</code></td>
1362      * <td><code>java.properties</code></td>
1363      * </tr>
1364      * <tr>
1365      * <th scope="row">5</th>
1366      * <td><code>Locale("")</code></td>
1367      * <td><code>java.class</code></td>
1368      * </tr>
1369      * <tr>
1370      * <th scope="row">6</th>
1371      * <td><code>Locale("")</code></td>
1372      * <td><code>java.properties</code></td>
1373      * </tr>
1374      * </tbody>
1375      * </table>
1376      * </li>
1377      *
1378      * <li>If the previous step has found no resource bundle, proceed to
1379      * Step 6. If a bundle has been found that is a base bundle (a bundle
1380      * for <code>Locale("")</code>), and the candidate locale list only contained
1381      * <code>Locale("")</code>, return the bundle to the caller. If a bundle
1382      * has been found that is a base bundle, but the candidate locale list
1383      * contained locales other than Locale(""), put the bundle on hold and
1384      * proceed to Step 6. If a bundle has been found that is not a base
1385      * bundle, proceed to Step 7.</li>
1386      *
1387      * <li>The {@link ResourceBundle.Control#getFallbackLocale(String,
1388      * Locale) control.getFallbackLocale} method is called to get a fallback
1389      * locale (alternative to the current target locale) to try further
1390      * finding a resource bundle. If the method returns a non-null locale,
1391      * it becomes the next target locale and the loading process starts over
1392      * from Step 3. Otherwise, if a base bundle was found and put on hold in
1393      * a previous Step 5, it is returned to the caller now. Otherwise, a
1394      * MissingResourceException is thrown.</li>
1395      *
1396      * <li>At this point, we have found a resource bundle that's not the
1397      * base bundle. If this bundle set its parent during its instantiation,
1398      * it is returned to the caller. Otherwise, its <a
1399      * href="./ResourceBundle.html#parent_chain">parent chain</a> is
1400      * instantiated based on the list of candidate locales from which it was
1401      * found. Finally, the bundle is returned to the caller.</li>
1402      * </ol>
1403      *
1404      * <p>During the resource bundle loading process above, this factory
1405      * method looks up the cache before calling the {@link
1406      * Control#newBundle(String, Locale, String, ClassLoader, boolean)
1407      * control.newBundle} method.  If the time-to-live period of the
1408      * resource bundle found in the cache has expired, the factory method
1409      * calls the {@link ResourceBundle.Control#needsReload(String, Locale,
1410      * String, ClassLoader, ResourceBundle, long) control.needsReload}
1411      * method to determine whether the resource bundle needs to be reloaded.
1412      * If reloading is required, the factory method calls
1413      * <code>control.newBundle</code> to reload the resource bundle.  If
1414      * <code>control.newBundle</code> returns <code>null</code>, the factory
1415      * method puts a dummy resource bundle in the cache as a mark of
1416      * nonexistent resource bundles in order to avoid lookup overhead for
1417      * subsequent requests. Such dummy resource bundles are under the same
1418      * expiration control as specified by <code>control</code>.
1419      *
1420      * <p>All resource bundles loaded are cached by default. Refer to
1421      * {@link Control#getTimeToLive(String,Locale)
1422      * control.getTimeToLive} for details.
1423      *
1424      * <p>The following is an example of the bundle loading process with the
1425      * default <code>ResourceBundle.Control</code> implementation.
1426      *
1427      * <p>Conditions:
1428      * <ul>
1429      * <li>Base bundle name: <code>foo.bar.Messages</code>
1430      * <li>Requested <code>Locale</code>: {@link Locale#ITALY}</li>
1431      * <li>Default <code>Locale</code>: {@link Locale#FRENCH}</li>
1432      * <li>Available resource bundles:
1433      * <code>foo/bar/Messages_fr.properties</code> and
1434      * <code>foo/bar/Messages.properties</code></li>
1435      * </ul>
1436      *
1437      * <p>First, <code>getBundle</code> tries loading a resource bundle in
1438      * the following sequence.
1439      *
1440      * <ul>
1441      * <li>class <code>foo.bar.Messages_it_IT</code>
1442      * <li>file <code>foo/bar/Messages_it_IT.properties</code>
1443      * <li>class <code>foo.bar.Messages_it</code></li>
1444      * <li>file <code>foo/bar/Messages_it.properties</code></li>
1445      * <li>class <code>foo.bar.Messages</code></li>
1446      * <li>file <code>foo/bar/Messages.properties</code></li>
1447      * </ul>
1448      *
1449      * <p>At this point, <code>getBundle</code> finds
1450      * <code>foo/bar/Messages.properties</code>, which is put on hold
1451      * because it's the base bundle.  <code>getBundle</code> calls {@link
1452      * Control#getFallbackLocale(String, Locale)
1453      * control.getFallbackLocale("foo.bar.Messages", Locale.ITALY)} which
1454      * returns <code>Locale.FRENCH</code>. Next, <code>getBundle</code>
1455      * tries loading a bundle in the following sequence.
1456      *
1457      * <ul>
1458      * <li>class <code>foo.bar.Messages_fr</code></li>
1459      * <li>file <code>foo/bar/Messages_fr.properties</code></li>
1460      * <li>class <code>foo.bar.Messages</code></li>
1461      * <li>file <code>foo/bar/Messages.properties</code></li>
1462      * </ul>
1463      *
1464      * <p><code>getBundle</code> finds
1465      * <code>foo/bar/Messages_fr.properties</code> and creates a
1466      * <code>ResourceBundle</code> instance. Then, <code>getBundle</code>
1467      * sets up its parent chain from the list of the candidate locales.  Only
1468      * <code>foo/bar/Messages.properties</code> is found in the list and
1469      * <code>getBundle</code> creates a <code>ResourceBundle</code> instance
1470      * that becomes the parent of the instance for
1471      * <code>foo/bar/Messages_fr.properties</code>.
1472      *
1473      * @param baseName
1474      *        the base name of the resource bundle, a fully qualified
1475      *        class name
1476      * @param targetLocale
1477      *        the locale for which a resource bundle is desired
1478      * @param loader
1479      *        the class loader from which to load the resource bundle
1480      * @param control
1481      *        the control which gives information for the resource
1482      *        bundle loading process
1483      * @return a resource bundle for the given base name and locale
1484      * @throws NullPointerException
1485      *         if <code>baseName</code>, <code>targetLocale</code>,
1486      *         <code>loader</code>, or <code>control</code> is
1487      *         <code>null</code>
1488      * @throws MissingResourceException
1489      *         if no resource bundle for the specified base name can be found
1490      * @throws IllegalArgumentException
1491      *         if the given <code>control</code> doesn't perform properly
1492      *         (e.g., <code>control.getCandidateLocales</code> returns null.)
1493      *         Note that validation of <code>control</code> is performed as
1494      *         needed.
1495      * @throws UnsupportedOperationException
1496      *         if this method is called in a named module
1497      * @since 1.6
1498      * @revised 9
1499      * @spec JPMS
1500      */
1501     @CallerSensitive
1502     public static ResourceBundle getBundle(String baseName, Locale targetLocale,
1503                                            ClassLoader loader, Control control) {
1504         if (loader == null || control == null) {
1505             throw new NullPointerException();
1506         }
1507         Class<?> caller = Reflection.getCallerClass();
1508         checkNamedModule(caller);
1509         return getBundleImpl(baseName, targetLocale, caller, loader, control);
1510     }
1511 
1512     private static Control getDefaultControl(Class<?> caller, String baseName) {
1513         return getDefaultControl(caller.getModule(), baseName);
1514     }
1515 
1516     private static Control getDefaultControl(Module targetModule, String baseName) {
1517         return targetModule.isNamed() ?
1518             Control.INSTANCE :
1519             ResourceBundleControlProviderHolder.getControl(baseName);
1520     }
1521 
1522     private static class ResourceBundleControlProviderHolder {
1523         private static final PrivilegedAction<List<ResourceBundleControlProvider>> pa =
1524             () -> {
1525                 return Collections.unmodifiableList(
1526                     ServiceLoader.load(ResourceBundleControlProvider.class,
1527                                        ClassLoader.getSystemClassLoader()).stream()
1528                         .map(ServiceLoader.Provider::get)
1529                         .collect(Collectors.toList()));
1530             };
1531 
1532         private static final List<ResourceBundleControlProvider> CONTROL_PROVIDERS =
1533             AccessController.doPrivileged(pa);
1534 
1535         private static Control getControl(String baseName) {
1536             return CONTROL_PROVIDERS.isEmpty() ?
1537                 Control.INSTANCE :
1538                 CONTROL_PROVIDERS.stream()
1539                     .flatMap(provider -> Stream.ofNullable(provider.getControl(baseName)))
1540                     .findFirst()
1541                     .orElse(Control.INSTANCE);
1542         }
1543     }
1544 
1545     private static void checkNamedModule(Class<?> caller) {
1546         if (caller.getModule().isNamed()) {
1547             throw new UnsupportedOperationException(
1548                     "ResourceBundle.Control not supported in named modules");
1549         }
1550     }
1551 
1552     private static ResourceBundle getBundleImpl(String baseName,
1553                                                 Locale locale,
1554                                                 Class<?> caller,
1555                                                 Control control) {
1556         return getBundleImpl(baseName, locale, caller, caller.getClassLoader(), control);
1557     }
1558 
1559     /**
1560      * This method will find resource bundles using the legacy mechanism
1561      * if the caller is unnamed module or the given class loader is
1562      * not the class loader of the caller module getting the resource
1563      * bundle, i.e. find the class that is visible to the class loader
1564      * and properties from unnamed module.
1565      *
1566      * The module-aware resource bundle lookup mechanism will load
1567      * the service providers using the service loader mechanism
1568      * as well as properties local in the caller module.
1569      */
1570     private static ResourceBundle getBundleImpl(String baseName,
1571                                                 Locale locale,
1572                                                 Class<?> caller,
1573                                                 ClassLoader loader,
1574                                                 Control control) {
1575         if (caller == null) {
1576             throw new InternalError("null caller");
1577         }
1578         Module callerModule = caller.getModule();
1579 
1580         // get resource bundles for a named module only if loader is the module's class loader
1581         if (callerModule.isNamed() && loader == getLoader(callerModule)) {
1582             return getBundleImpl(callerModule, callerModule, baseName, locale, control);
1583         }
1584 
1585         // find resource bundles from unnamed module of given class loader
1586         // Java agent can add to the bootclasspath e.g. via
1587         // java.lang.instrument.Instrumentation and load classes in unnamed module.
1588         // It may call RB::getBundle that will end up here with loader == null.
1589         Module unnamedModule = loader != null
1590             ? loader.getUnnamedModule()
1591             : BootLoader.getUnnamedModule();
1592 
1593         return getBundleImpl(callerModule, unnamedModule, baseName, locale, control);
1594     }
1595 
1596     private static ResourceBundle getBundleFromModule(Class<?> caller,
1597                                                       Module module,
1598                                                       String baseName,
1599                                                       Locale locale,
1600                                                       Control control) {
1601         Objects.requireNonNull(module);
1602         Module callerModule = caller.getModule();
1603         if (callerModule != module) {
1604             SecurityManager sm = System.getSecurityManager();
1605             if (sm != null) {
1606                 sm.checkPermission(GET_CLASSLOADER_PERMISSION);
1607             }
1608         }
1609         return getBundleImpl(callerModule, module, baseName, locale, control);
1610     }
1611 
1612     private static ResourceBundle getBundleImpl(Module callerModule,
1613                                                 Module module,
1614                                                 String baseName,
1615                                                 Locale locale,
1616                                                 Control control) {
1617         if (locale == null || control == null) {
1618             throw new NullPointerException();
1619         }
1620 
1621         // We create a CacheKey here for use by this call. The base name
1622         // and modules will never change during the bundle loading
1623         // process. We have to make sure that the locale is set before
1624         // using it as a cache key.
1625         CacheKey cacheKey = new CacheKey(baseName, locale, module, callerModule);
1626         ResourceBundle bundle = null;
1627 
1628         // Quick lookup of the cache.
1629         BundleReference bundleRef = cacheList.get(cacheKey);
1630         if (bundleRef != null) {
1631             bundle = bundleRef.get();
1632             bundleRef = null;
1633         }
1634 
1635         // If this bundle and all of its parents are valid (not expired),
1636         // then return this bundle. If any of the bundles is expired, we
1637         // don't call control.needsReload here but instead drop into the
1638         // complete loading process below.
1639         if (isValidBundle(bundle) && hasValidParentChain(bundle)) {
1640             return bundle;
1641         }
1642 
1643         // No valid bundle was found in the cache, so we need to load the
1644         // resource bundle and its parents.
1645 
1646         boolean isKnownControl = (control == Control.INSTANCE) ||
1647                                    (control instanceof SingleFormatControl);
1648         List<String> formats = control.getFormats(baseName);
1649         if (!isKnownControl && !checkList(formats)) {
1650             throw new IllegalArgumentException("Invalid Control: getFormats");
1651         }
1652 
1653         ResourceBundle baseBundle = null;
1654         for (Locale targetLocale = locale;
1655              targetLocale != null;
1656              targetLocale = control.getFallbackLocale(baseName, targetLocale)) {
1657             List<Locale> candidateLocales = control.getCandidateLocales(baseName, targetLocale);
1658             if (!isKnownControl && !checkList(candidateLocales)) {
1659                 throw new IllegalArgumentException("Invalid Control: getCandidateLocales");
1660             }
1661 
1662             bundle = findBundle(callerModule, module, cacheKey,
1663                                 candidateLocales, formats, 0, control, baseBundle);
1664 
1665             // If the loaded bundle is the base bundle and exactly for the
1666             // requested locale or the only candidate locale, then take the
1667             // bundle as the resulting one. If the loaded bundle is the base
1668             // bundle, it's put on hold until we finish processing all
1669             // fallback locales.
1670             if (isValidBundle(bundle)) {
1671                 boolean isBaseBundle = Locale.ROOT.equals(bundle.locale);
1672                 if (!isBaseBundle || bundle.locale.equals(locale)
1673                     || (candidateLocales.size() == 1
1674                         && bundle.locale.equals(candidateLocales.get(0)))) {
1675                     break;
1676                 }
1677 
1678                 // If the base bundle has been loaded, keep the reference in
1679                 // baseBundle so that we can avoid any redundant loading in case
1680                 // the control specify not to cache bundles.
1681                 if (isBaseBundle && baseBundle == null) {
1682                     baseBundle = bundle;
1683                 }
1684             }
1685         }
1686 
1687         if (bundle == null) {
1688             if (baseBundle == null) {
1689                 throwMissingResourceException(baseName, locale, cacheKey.getCause());
1690             }
1691             bundle = baseBundle;
1692         }
1693 
1694         // keep callerModule and module reachable for as long as we are operating
1695         // with WeakReference(s) to them (in CacheKey)...
1696         Reference.reachabilityFence(callerModule);
1697         Reference.reachabilityFence(module);
1698 
1699         return bundle;
1700     }
1701 
1702     /**
1703      * Checks if the given <code>List</code> is not null, not empty,
1704      * not having null in its elements.
1705      */
1706     private static boolean checkList(List<?> a) {
1707         boolean valid = (a != null && !a.isEmpty());
1708         if (valid) {
1709             int size = a.size();
1710             for (int i = 0; valid && i < size; i++) {
1711                 valid = (a.get(i) != null);
1712             }
1713         }
1714         return valid;
1715     }
1716 
1717     private static ResourceBundle findBundle(Module callerModule,
1718                                              Module module,
1719                                              CacheKey cacheKey,
1720                                              List<Locale> candidateLocales,
1721                                              List<String> formats,
1722                                              int index,
1723                                              Control control,
1724                                              ResourceBundle baseBundle) {
1725         Locale targetLocale = candidateLocales.get(index);
1726         ResourceBundle parent = null;
1727         if (index != candidateLocales.size() - 1) {
1728             parent = findBundle(callerModule, module, cacheKey,
1729                                 candidateLocales, formats, index + 1,
1730                                 control, baseBundle);
1731         } else if (baseBundle != null && Locale.ROOT.equals(targetLocale)) {
1732             return baseBundle;
1733         }
1734 
1735         // Before we do the real loading work, see whether we need to
1736         // do some housekeeping: If references to modules or
1737         // resource bundles have been nulled out, remove all related
1738         // information from the cache.
1739         Object ref;
1740         while ((ref = referenceQueue.poll()) != null) {
1741             cacheList.remove(((CacheKeyReference)ref).getCacheKey());
1742         }
1743 
1744         // flag indicating the resource bundle has expired in the cache
1745         boolean expiredBundle = false;
1746 
1747         // First, look up the cache to see if it's in the cache, without
1748         // attempting to load bundle.
1749         cacheKey.setLocale(targetLocale);
1750         ResourceBundle bundle = findBundleInCache(cacheKey, control);
1751         if (isValidBundle(bundle)) {
1752             expiredBundle = bundle.expired;
1753             if (!expiredBundle) {
1754                 // If its parent is the one asked for by the candidate
1755                 // locales (the runtime lookup path), we can take the cached
1756                 // one. (If it's not identical, then we'd have to check the
1757                 // parent's parents to be consistent with what's been
1758                 // requested.)
1759                 if (bundle.parent == parent) {
1760                     return bundle;
1761                 }
1762                 // Otherwise, remove the cached one since we can't keep
1763                 // the same bundles having different parents.
1764                 BundleReference bundleRef = cacheList.get(cacheKey);
1765                 if (bundleRef != null && bundleRef.get() == bundle) {
1766                     cacheList.remove(cacheKey, bundleRef);
1767                 }
1768             }
1769         }
1770 
1771         if (bundle != NONEXISTENT_BUNDLE) {
1772             trace("findBundle: %d %s %s formats: %s%n", index, candidateLocales, cacheKey, formats);
1773             if (module.isNamed()) {
1774                 bundle = loadBundle(cacheKey, formats, control, module, callerModule);
1775             } else {
1776                 bundle = loadBundle(cacheKey, formats, control, expiredBundle);
1777             }
1778             if (bundle != null) {
1779                 if (bundle.parent == null) {
1780                     bundle.setParent(parent);
1781                 }
1782                 bundle.locale = targetLocale;
1783                 bundle = putBundleInCache(cacheKey, bundle, control);
1784                 return bundle;
1785             }
1786 
1787             // Put NONEXISTENT_BUNDLE in the cache as a mark that there's no bundle
1788             // instance for the locale.
1789             putBundleInCache(cacheKey, NONEXISTENT_BUNDLE, control);
1790         }
1791         return parent;
1792     }
1793 
1794     private static final String UNKNOWN_FORMAT = "";
1795 
1796 
1797     /*
1798      * Loads a ResourceBundle in named modules
1799      */
1800     private static ResourceBundle loadBundle(CacheKey cacheKey,
1801                                              List<String> formats,
1802                                              Control control,
1803                                              Module module,
1804                                              Module callerModule) {
1805         String baseName = cacheKey.getName();
1806         Locale targetLocale = cacheKey.getLocale();
1807 
1808         ResourceBundle bundle = null;
1809         if (cacheKey.hasProviders()) {
1810             if (callerModule == module) {
1811                 bundle = loadBundleFromProviders(baseName,
1812                                                  targetLocale,
1813                                                  cacheKey.getProviders(),
1814                                                  cacheKey);
1815             } else {
1816                 // load from provider if the caller module has access to the
1817                 // service type and also declares `uses`
1818                 ClassLoader loader = getLoader(module);
1819                 Class<ResourceBundleProvider> svc =
1820                     getResourceBundleProviderType(baseName, loader);
1821                 if (svc != null
1822                         && Reflection.verifyModuleAccess(callerModule, svc)
1823                         && callerModule.canUse(svc)) {
1824                     bundle = loadBundleFromProviders(baseName,
1825                                                      targetLocale,
1826                                                      cacheKey.getProviders(),
1827                                                      cacheKey);
1828                 }
1829             }
1830 
1831             if (bundle != null) {
1832                 cacheKey.setFormat(UNKNOWN_FORMAT);
1833             }
1834         }
1835 
1836         // If none of providers returned a bundle and the caller has no provider,
1837         // look up module-local bundles or from the class path
1838         if (bundle == null && !cacheKey.callerHasProvider()) {
1839             for (String format : formats) {
1840                 try {
1841                     switch (format) {
1842                     case "java.class":
1843                         bundle = ResourceBundleProviderHelper
1844                             .loadResourceBundle(callerModule, module, baseName, targetLocale);
1845 
1846                         break;
1847                     case "java.properties":
1848                         bundle = ResourceBundleProviderHelper
1849                             .loadPropertyResourceBundle(callerModule, module, baseName, targetLocale);
1850                         break;
1851                     default:
1852                         throw new InternalError("unexpected format: " + format);
1853                     }
1854 
1855                     if (bundle != null) {
1856                         cacheKey.setFormat(format);
1857                         break;
1858                     }
1859                 } catch (LinkageError|Exception e) {
1860                     cacheKey.setCause(e);
1861                 }
1862             }
1863         }
1864         return bundle;
1865     }
1866 
1867     /**
1868      * Returns a ServiceLoader that will find providers that are bound to
1869      * a given named module.
1870      */
1871     private static ServiceLoader<ResourceBundleProvider> getServiceLoader(Module module,
1872                                                                           String baseName)
1873     {
1874         if (!module.isNamed()) {
1875             return null;
1876         }
1877 
1878         ClassLoader loader = getLoader(module);
1879         Class<ResourceBundleProvider> service =
1880                 getResourceBundleProviderType(baseName, loader);
1881         if (service != null && Reflection.verifyModuleAccess(module, service)) {
1882             try {
1883                 // locate providers that are visible to the class loader
1884                 // ServiceConfigurationError will be thrown if the module
1885                 // does not declare `uses` the service type
1886                 return ServiceLoader.load(service, loader, module);
1887             } catch (ServiceConfigurationError e) {
1888                 // "uses" not declared
1889                 return null;
1890             }
1891         }
1892         return null;
1893     }
1894 
1895     /**
1896      * Returns the service type of the given baseName that is visible
1897      * to the given class loader
1898      */
1899     private static Class<ResourceBundleProvider>
1900             getResourceBundleProviderType(String baseName, ClassLoader loader)
1901     {
1902         // Look up <packagename> + ".spi." + <name>"Provider"
1903         int i = baseName.lastIndexOf('.');
1904         if (i <= 0) {
1905             return null;
1906         }
1907 
1908         String name = baseName.substring(i+1, baseName.length()) + "Provider";
1909         String providerName = baseName.substring(0, i) + ".spi." + name;
1910 
1911         // Use the class loader of the getBundle caller so that the caller's
1912         // visibility of the provider type is checked.
1913         return AccessController.doPrivileged(
1914             new PrivilegedAction<>() {
1915                 @Override
1916                 public Class<ResourceBundleProvider> run() {
1917                     try {
1918                         Class<?> c = Class.forName(providerName, false, loader);
1919                         if (ResourceBundleProvider.class.isAssignableFrom(c)) {
1920                             @SuppressWarnings("unchecked")
1921                             Class<ResourceBundleProvider> s = (Class<ResourceBundleProvider>) c;
1922                             return s;
1923                         }
1924                     } catch (ClassNotFoundException e) {}
1925                     return null;
1926                 }
1927             });
1928     }
1929 
1930     /**
1931      * Loads ResourceBundle from service providers.
1932      */
1933     private static ResourceBundle loadBundleFromProviders(String baseName,
1934                                                           Locale locale,
1935                                                           ServiceLoader<ResourceBundleProvider> providers,
1936                                                           CacheKey cacheKey)
1937     {
1938         if (providers == null) return null;
1939 
1940         return AccessController.doPrivileged(
1941                 new PrivilegedAction<>() {
1942                     public ResourceBundle run() {
1943                         for (Iterator<ResourceBundleProvider> itr = providers.iterator(); itr.hasNext(); ) {
1944                             try {
1945                                 ResourceBundleProvider provider = itr.next();
1946                                 if (cacheKey != null && cacheKey.callerHasProvider == null
1947                                         && cacheKey.getModule() == provider.getClass().getModule()) {
1948                                     cacheKey.callerHasProvider = Boolean.TRUE;
1949                                 }
1950                                 ResourceBundle bundle = provider.getBundle(baseName, locale);
1951                                 trace("provider %s %s locale: %s bundle: %s%n", provider, baseName, locale, bundle);
1952                                 if (bundle != null) {
1953                                     return bundle;
1954                                 }
1955                             } catch (ServiceConfigurationError | SecurityException e) {
1956                                 if (cacheKey != null) {
1957                                     cacheKey.setCause(e);
1958                                 }
1959                             }
1960                         }
1961                         if (cacheKey != null && cacheKey.callerHasProvider == null) {
1962                             cacheKey.callerHasProvider = Boolean.FALSE;
1963                         }
1964                         return null;
1965                     }
1966                 });
1967 
1968     }
1969 
1970     /*
1971      * Legacy mechanism to load resource bundles
1972      */
1973     private static ResourceBundle loadBundle(CacheKey cacheKey,
1974                                              List<String> formats,
1975                                              Control control,
1976                                              boolean reload) {
1977 
1978         // Here we actually load the bundle in the order of formats
1979         // specified by the getFormats() value.
1980         Locale targetLocale = cacheKey.getLocale();
1981 
1982         Module module = cacheKey.getModule();
1983         if (module == null) {
1984             // should not happen
1985             throw new InternalError(
1986                 "Module for cache key: " + cacheKey + " has been GCed.");
1987         }
1988         ClassLoader loader = getLoaderForControl(module);
1989 
1990         ResourceBundle bundle = null;
1991         for (String format : formats) {
1992             try {
1993                 // ResourceBundle.Control.newBundle may be overridden
1994                 bundle = control.newBundle(cacheKey.getName(), targetLocale, format,
1995                                            loader, reload);
1996             } catch (LinkageError | Exception error) {
1997                 // We need to handle the LinkageError case due to
1998                 // inconsistent case-sensitivity in ClassLoader.
1999                 // See 6572242 for details.
2000                 cacheKey.setCause(error);
2001             }
2002             if (bundle != null) {
2003                 // Set the format in the cache key so that it can be
2004                 // used when calling needsReload later.
2005                 cacheKey.setFormat(format);
2006                 bundle.name = cacheKey.getName();
2007                 bundle.locale = targetLocale;
2008                 // Bundle provider might reuse instances. So we should make
2009                 // sure to clear the expired flag here.
2010                 bundle.expired = false;
2011                 break;
2012             }
2013         }
2014 
2015         return bundle;
2016     }
2017 
2018     private static boolean isValidBundle(ResourceBundle bundle) {
2019         return bundle != null && bundle != NONEXISTENT_BUNDLE;
2020     }
2021 
2022     /**
2023      * Determines whether any of resource bundles in the parent chain,
2024      * including the leaf, have expired.
2025      */
2026     private static boolean hasValidParentChain(ResourceBundle bundle) {
2027         long now = System.currentTimeMillis();
2028         while (bundle != null) {
2029             if (bundle.expired) {
2030                 return false;
2031             }
2032             CacheKey key = bundle.cacheKey;
2033             if (key != null) {
2034                 long expirationTime = key.expirationTime;
2035                 if (expirationTime >= 0 && expirationTime <= now) {
2036                     return false;
2037                 }
2038             }
2039             bundle = bundle.parent;
2040         }
2041         return true;
2042     }
2043 
2044     /**
2045      * Throw a MissingResourceException with proper message
2046      */
2047     private static void throwMissingResourceException(String baseName,
2048                                                       Locale locale,
2049                                                       Throwable cause) {
2050         // If the cause is a MissingResourceException, avoid creating
2051         // a long chain. (6355009)
2052         if (cause instanceof MissingResourceException) {
2053             cause = null;
2054         }
2055         throw new MissingResourceException("Can't find bundle for base name "
2056                                            + baseName + ", locale " + locale,
2057                                            baseName + "_" + locale, // className
2058                                            "",                      // key
2059                                            cause);
2060     }
2061 
2062     /**
2063      * Finds a bundle in the cache. Any expired bundles are marked as
2064      * `expired' and removed from the cache upon return.
2065      *
2066      * @param cacheKey the key to look up the cache
2067      * @param control the Control to be used for the expiration control
2068      * @return the cached bundle, or null if the bundle is not found in the
2069      * cache or its parent has expired. <code>bundle.expire</code> is true
2070      * upon return if the bundle in the cache has expired.
2071      */
2072     private static ResourceBundle findBundleInCache(CacheKey cacheKey,
2073                                                     Control control) {
2074         BundleReference bundleRef = cacheList.get(cacheKey);
2075         if (bundleRef == null) {
2076             return null;
2077         }
2078         ResourceBundle bundle = bundleRef.get();
2079         if (bundle == null) {
2080             return null;
2081         }
2082         ResourceBundle p = bundle.parent;
2083         assert p != NONEXISTENT_BUNDLE;
2084         // If the parent has expired, then this one must also expire. We
2085         // check only the immediate parent because the actual loading is
2086         // done from the root (base) to leaf (child) and the purpose of
2087         // checking is to propagate expiration towards the leaf. For
2088         // example, if the requested locale is ja_JP_JP and there are
2089         // bundles for all of the candidates in the cache, we have a list,
2090         //
2091         // base <- ja <- ja_JP <- ja_JP_JP
2092         //
2093         // If ja has expired, then it will reload ja and the list becomes a
2094         // tree.
2095         //
2096         // base <- ja (new)
2097         //  "   <- ja (expired) <- ja_JP <- ja_JP_JP
2098         //
2099         // When looking up ja_JP in the cache, it finds ja_JP in the cache
2100         // which references to the expired ja. Then, ja_JP is marked as
2101         // expired and removed from the cache. This will be propagated to
2102         // ja_JP_JP.
2103         //
2104         // Now, it's possible, for example, that while loading new ja_JP,
2105         // someone else has started loading the same bundle and finds the
2106         // base bundle has expired. Then, what we get from the first
2107         // getBundle call includes the expired base bundle. However, if
2108         // someone else didn't start its loading, we wouldn't know if the
2109         // base bundle has expired at the end of the loading process. The
2110         // expiration control doesn't guarantee that the returned bundle and
2111         // its parents haven't expired.
2112         //
2113         // We could check the entire parent chain to see if there's any in
2114         // the chain that has expired. But this process may never end. An
2115         // extreme case would be that getTimeToLive returns 0 and
2116         // needsReload always returns true.
2117         if (p != null && p.expired) {
2118             assert bundle != NONEXISTENT_BUNDLE;
2119             bundle.expired = true;
2120             bundle.cacheKey = null;
2121             cacheList.remove(cacheKey, bundleRef);
2122             bundle = null;
2123         } else {
2124             CacheKey key = bundleRef.getCacheKey();
2125             long expirationTime = key.expirationTime;
2126             if (!bundle.expired && expirationTime >= 0 &&
2127                 expirationTime <= System.currentTimeMillis()) {
2128                 // its TTL period has expired.
2129                 if (bundle != NONEXISTENT_BUNDLE) {
2130                     // Synchronize here to call needsReload to avoid
2131                     // redundant concurrent calls for the same bundle.
2132                     synchronized (bundle) {
2133                         expirationTime = key.expirationTime;
2134                         if (!bundle.expired && expirationTime >= 0 &&
2135                             expirationTime <= System.currentTimeMillis()) {
2136                             try {
2137                                 Module module = cacheKey.getModule();
2138                                 bundle.expired =
2139                                     module == null || // already GCed
2140                                     control.needsReload(key.getName(),
2141                                                         key.getLocale(),
2142                                                         key.getFormat(),
2143                                                         getLoaderForControl(module),
2144                                                         bundle,
2145                                                         key.loadTime);
2146                             } catch (Exception e) {
2147                                 cacheKey.setCause(e);
2148                             }
2149                             if (bundle.expired) {
2150                                 // If the bundle needs to be reloaded, then
2151                                 // remove the bundle from the cache, but
2152                                 // return the bundle with the expired flag
2153                                 // on.
2154                                 bundle.cacheKey = null;
2155                                 cacheList.remove(cacheKey, bundleRef);
2156                             } else {
2157                                 // Update the expiration control info. and reuse
2158                                 // the same bundle instance
2159                                 setExpirationTime(key, control);
2160                             }
2161                         }
2162                     }
2163                 } else {
2164                     // We just remove NONEXISTENT_BUNDLE from the cache.
2165                     cacheList.remove(cacheKey, bundleRef);
2166                     bundle = null;
2167                 }
2168             }
2169         }
2170         return bundle;
2171     }
2172 
2173     /**
2174      * Put a new bundle in the cache.
2175      *
2176      * @param cacheKey the key for the resource bundle
2177      * @param bundle the resource bundle to be put in the cache
2178      * @return the ResourceBundle for the cacheKey; if someone has put
2179      * the bundle before this call, the one found in the cache is
2180      * returned.
2181      */
2182     private static ResourceBundle putBundleInCache(CacheKey cacheKey,
2183                                                    ResourceBundle bundle,
2184                                                    Control control) {
2185         setExpirationTime(cacheKey, control);
2186         if (cacheKey.expirationTime != Control.TTL_DONT_CACHE) {
2187             CacheKey key = new CacheKey(cacheKey);
2188             BundleReference bundleRef = new BundleReference(bundle, referenceQueue, key);
2189             bundle.cacheKey = key;
2190 
2191             // Put the bundle in the cache if it's not been in the cache.
2192             BundleReference result = cacheList.putIfAbsent(key, bundleRef);
2193 
2194             // If someone else has put the same bundle in the cache before
2195             // us and it has not expired, we should use the one in the cache.
2196             if (result != null) {
2197                 ResourceBundle rb = result.get();
2198                 if (rb != null && !rb.expired) {
2199                     // Clear the back link to the cache key
2200                     bundle.cacheKey = null;
2201                     bundle = rb;
2202                     // Clear the reference in the BundleReference so that
2203                     // it won't be enqueued.
2204                     bundleRef.clear();
2205                 } else {
2206                     // Replace the invalid (garbage collected or expired)
2207                     // instance with the valid one.
2208                     cacheList.put(key, bundleRef);
2209                 }
2210             }
2211         }
2212         return bundle;
2213     }
2214 
2215     private static void setExpirationTime(CacheKey cacheKey, Control control) {
2216         long ttl = control.getTimeToLive(cacheKey.getName(),
2217                                          cacheKey.getLocale());
2218         if (ttl >= 0) {
2219             // If any expiration time is specified, set the time to be
2220             // expired in the cache.
2221             long now = System.currentTimeMillis();
2222             cacheKey.loadTime = now;
2223             cacheKey.expirationTime = now + ttl;
2224         } else if (ttl >= Control.TTL_NO_EXPIRATION_CONTROL) {
2225             cacheKey.expirationTime = ttl;
2226         } else {
2227             throw new IllegalArgumentException("Invalid Control: TTL=" + ttl);
2228         }
2229     }
2230 
2231     /**
2232      * Removes all resource bundles from the cache that have been loaded
2233      * by the caller's module.
2234      *
2235      * @since 1.6
2236      * @revised 9
2237      * @spec JPMS
2238      * @see ResourceBundle.Control#getTimeToLive(String,Locale)
2239      */
2240     @CallerSensitive
2241     public static final void clearCache() {
2242         Class<?> caller = Reflection.getCallerClass();
2243         cacheList.keySet().removeIf(
2244             key -> key.getCallerModule() == caller.getModule()
2245         );
2246     }
2247 
2248     /**
2249      * Removes all resource bundles from the cache that have been loaded
2250      * by the given class loader.
2251      *
2252      * @param loader the class loader
2253      * @exception NullPointerException if <code>loader</code> is null
2254      * @since 1.6
2255      * @see ResourceBundle.Control#getTimeToLive(String,Locale)
2256      */
2257     public static final void clearCache(ClassLoader loader) {
2258         Objects.requireNonNull(loader);
2259         cacheList.keySet().removeIf(
2260             key -> {
2261                 Module m;
2262                 return (m = key.getModule()) != null &&
2263                        getLoader(m) == loader;
2264             }
2265         );
2266     }
2267 
2268     /**
2269      * Gets an object for the given key from this resource bundle.
2270      * Returns null if this resource bundle does not contain an
2271      * object for the given key.
2272      *
2273      * @param key the key for the desired object
2274      * @exception NullPointerException if <code>key</code> is <code>null</code>
2275      * @return the object for the given key, or null
2276      */
2277     protected abstract Object handleGetObject(String key);
2278 
2279     /**
2280      * Returns an enumeration of the keys.
2281      *
2282      * @return an <code>Enumeration</code> of the keys contained in
2283      *         this <code>ResourceBundle</code> and its parent bundles.
2284      */
2285     public abstract Enumeration<String> getKeys();
2286 
2287     /**
2288      * Determines whether the given <code>key</code> is contained in
2289      * this <code>ResourceBundle</code> or its parent bundles.
2290      *
2291      * @param key
2292      *        the resource <code>key</code>
2293      * @return <code>true</code> if the given <code>key</code> is
2294      *        contained in this <code>ResourceBundle</code> or its
2295      *        parent bundles; <code>false</code> otherwise.
2296      * @exception NullPointerException
2297      *         if <code>key</code> is <code>null</code>
2298      * @since 1.6
2299      */
2300     public boolean containsKey(String key) {
2301         if (key == null) {
2302             throw new NullPointerException();
2303         }
2304         for (ResourceBundle rb = this; rb != null; rb = rb.parent) {
2305             if (rb.handleKeySet().contains(key)) {
2306                 return true;
2307             }
2308         }
2309         return false;
2310     }
2311 
2312     /**
2313      * Returns a <code>Set</code> of all keys contained in this
2314      * <code>ResourceBundle</code> and its parent bundles.
2315      *
2316      * @return a <code>Set</code> of all keys contained in this
2317      *         <code>ResourceBundle</code> and its parent bundles.
2318      * @since 1.6
2319      */
2320     public Set<String> keySet() {
2321         Set<String> keys = new HashSet<>();
2322         for (ResourceBundle rb = this; rb != null; rb = rb.parent) {
2323             keys.addAll(rb.handleKeySet());
2324         }
2325         return keys;
2326     }
2327 
2328     /**
2329      * Returns a <code>Set</code> of the keys contained <em>only</em>
2330      * in this <code>ResourceBundle</code>.
2331      *
2332      * <p>The default implementation returns a <code>Set</code> of the
2333      * keys returned by the {@link #getKeys() getKeys} method except
2334      * for the ones for which the {@link #handleGetObject(String)
2335      * handleGetObject} method returns <code>null</code>. Once the
2336      * <code>Set</code> has been created, the value is kept in this
2337      * <code>ResourceBundle</code> in order to avoid producing the
2338      * same <code>Set</code> in subsequent calls. Subclasses can
2339      * override this method for faster handling.
2340      *
2341      * @return a <code>Set</code> of the keys contained only in this
2342      *        <code>ResourceBundle</code>
2343      * @since 1.6
2344      */
2345     protected Set<String> handleKeySet() {
2346         if (keySet == null) {
2347             synchronized (this) {
2348                 if (keySet == null) {
2349                     Set<String> keys = new HashSet<>();
2350                     Enumeration<String> enumKeys = getKeys();
2351                     while (enumKeys.hasMoreElements()) {
2352                         String key = enumKeys.nextElement();
2353                         if (handleGetObject(key) != null) {
2354                             keys.add(key);
2355                         }
2356                     }
2357                     keySet = keys;
2358                 }
2359             }
2360         }
2361         return keySet;
2362     }
2363 
2364 
2365 
2366     /**
2367      * <code>ResourceBundle.Control</code> defines a set of callback methods
2368      * that are invoked by the {@link ResourceBundle#getBundle(String,
2369      * Locale, ClassLoader, Control) ResourceBundle.getBundle} factory
2370      * methods during the bundle loading process. In other words, a
2371      * <code>ResourceBundle.Control</code> collaborates with the factory
2372      * methods for loading resource bundles. The default implementation of
2373      * the callback methods provides the information necessary for the
2374      * factory methods to perform the <a
2375      * href="./ResourceBundle.html#default_behavior">default behavior</a>.
2376      *
2377      * <p> {@link ResourceBundle.Control} is designed for an application deployed
2378      * in an unnamed module, for example to support resource bundles in
2379      * non-standard formats or package localized resources in a non-traditional
2380      * convention. {@link ResourceBundleProvider} is the replacement for
2381      * {@code ResourceBundle.Control} when migrating to modules.
2382      * {@code UnsupportedOperationException} will be thrown when a factory
2383      * method that takes the {@code ResourceBundle.Control} parameter is called.
2384      *
2385      * <p>In addition to the callback methods, the {@link
2386      * #toBundleName(String, Locale) toBundleName} and {@link
2387      * #toResourceName(String, String) toResourceName} methods are defined
2388      * primarily for convenience in implementing the callback
2389      * methods. However, the <code>toBundleName</code> method could be
2390      * overridden to provide different conventions in the organization and
2391      * packaging of localized resources.  The <code>toResourceName</code>
2392      * method is <code>final</code> to avoid use of wrong resource and class
2393      * name separators.
2394      *
2395      * <p>Two factory methods, {@link #getControl(List)} and {@link
2396      * #getNoFallbackControl(List)}, provide
2397      * <code>ResourceBundle.Control</code> instances that implement common
2398      * variations of the default bundle loading process.
2399      *
2400      * <p>The formats returned by the {@link Control#getFormats(String)
2401      * getFormats} method and candidate locales returned by the {@link
2402      * ResourceBundle.Control#getCandidateLocales(String, Locale)
2403      * getCandidateLocales} method must be consistent in all
2404      * <code>ResourceBundle.getBundle</code> invocations for the same base
2405      * bundle. Otherwise, the <code>ResourceBundle.getBundle</code> methods
2406      * may return unintended bundles. For example, if only
2407      * <code>"java.class"</code> is returned by the <code>getFormats</code>
2408      * method for the first call to <code>ResourceBundle.getBundle</code>
2409      * and only <code>"java.properties"</code> for the second call, then the
2410      * second call will return the class-based one that has been cached
2411      * during the first call.
2412      *
2413      * <p>A <code>ResourceBundle.Control</code> instance must be thread-safe
2414      * if it's simultaneously used by multiple threads.
2415      * <code>ResourceBundle.getBundle</code> does not synchronize to call
2416      * the <code>ResourceBundle.Control</code> methods. The default
2417      * implementations of the methods are thread-safe.
2418      *
2419      * <p>Applications can specify <code>ResourceBundle.Control</code>
2420      * instances returned by the <code>getControl</code> factory methods or
2421      * created from a subclass of <code>ResourceBundle.Control</code> to
2422      * customize the bundle loading process. The following are examples of
2423      * changing the default bundle loading process.
2424      *
2425      * <p><b>Example 1</b>
2426      *
2427      * <p>The following code lets <code>ResourceBundle.getBundle</code> look
2428      * up only properties-based resources.
2429      *
2430      * <pre>
2431      * import java.util.*;
2432      * import static java.util.ResourceBundle.Control.*;
2433      * ...
2434      * ResourceBundle bundle =
2435      *   ResourceBundle.getBundle("MyResources", new Locale("fr", "CH"),
2436      *                            ResourceBundle.Control.getControl(FORMAT_PROPERTIES));
2437      * </pre>
2438      *
2439      * Given the resource bundles in the <a
2440      * href="./ResourceBundle.html#default_behavior_example">example</a> in
2441      * the <code>ResourceBundle.getBundle</code> description, this
2442      * <code>ResourceBundle.getBundle</code> call loads
2443      * <code>MyResources_fr_CH.properties</code> whose parent is
2444      * <code>MyResources_fr.properties</code> whose parent is
2445      * <code>MyResources.properties</code>. (<code>MyResources_fr_CH.properties</code>
2446      * is not hidden, but <code>MyResources_fr_CH.class</code> is.)
2447      *
2448      * <p><b>Example 2</b>
2449      *
2450      * <p>The following is an example of loading XML-based bundles
2451      * using {@link Properties#loadFromXML(java.io.InputStream)
2452      * Properties.loadFromXML}.
2453      *
2454      * <pre>
2455      * ResourceBundle rb = ResourceBundle.getBundle("Messages",
2456      *     new ResourceBundle.Control() {
2457      *         public List&lt;String&gt; getFormats(String baseName) {
2458      *             if (baseName == null)
2459      *                 throw new NullPointerException();
2460      *             return Arrays.asList("xml");
2461      *         }
2462      *         public ResourceBundle newBundle(String baseName,
2463      *                                         Locale locale,
2464      *                                         String format,
2465      *                                         ClassLoader loader,
2466      *                                         boolean reload)
2467      *                          throws IllegalAccessException,
2468      *                                 InstantiationException,
2469      *                                 IOException {
2470      *             if (baseName == null || locale == null
2471      *                   || format == null || loader == null)
2472      *                 throw new NullPointerException();
2473      *             ResourceBundle bundle = null;
2474      *             if (format.equals("xml")) {
2475      *                 String bundleName = toBundleName(baseName, locale);
2476      *                 String resourceName = toResourceName(bundleName, format);
2477      *                 InputStream stream = null;
2478      *                 if (reload) {
2479      *                     URL url = loader.getResource(resourceName);
2480      *                     if (url != null) {
2481      *                         URLConnection connection = url.openConnection();
2482      *                         if (connection != null) {
2483      *                             // Disable caches to get fresh data for
2484      *                             // reloading.
2485      *                             connection.setUseCaches(false);
2486      *                             stream = connection.getInputStream();
2487      *                         }
2488      *                     }
2489      *                 } else {
2490      *                     stream = loader.getResourceAsStream(resourceName);
2491      *                 }
2492      *                 if (stream != null) {
2493      *                     BufferedInputStream bis = new BufferedInputStream(stream);
2494      *                     bundle = new XMLResourceBundle(bis);
2495      *                     bis.close();
2496      *                 }
2497      *             }
2498      *             return bundle;
2499      *         }
2500      *     });
2501      *
2502      * ...
2503      *
2504      * private static class XMLResourceBundle extends ResourceBundle {
2505      *     private Properties props;
2506      *     XMLResourceBundle(InputStream stream) throws IOException {
2507      *         props = new Properties();
2508      *         props.loadFromXML(stream);
2509      *     }
2510      *     protected Object handleGetObject(String key) {
2511      *         return props.getProperty(key);
2512      *     }
2513      *     public Enumeration&lt;String&gt; getKeys() {
2514      *         ...
2515      *     }
2516      * }
2517      * </pre>
2518      *
2519      * @apiNote {@code ResourceBundle.Control} is not supported
2520      * in named modules. If the {@code ResourceBundle.getBundle} method with
2521      * a {@code ResourceBundle.Control} is called in a named module, the method
2522      * will throw an {@link UnsupportedOperationException}. Any service providers
2523      * of {@link ResourceBundleControlProvider} are ignored in named modules.
2524      *
2525      * @since 1.6
2526      * @revised 9
2527      * @spec JPMS
2528      * @see java.util.spi.ResourceBundleProvider
2529      */
2530     public static class Control {
2531         /**
2532          * The default format <code>List</code>, which contains the strings
2533          * <code>"java.class"</code> and <code>"java.properties"</code>, in
2534          * this order. This <code>List</code> is unmodifiable.
2535          *
2536          * @see #getFormats(String)
2537          */
2538         public static final List<String> FORMAT_DEFAULT
2539             = List.of("java.class", "java.properties");
2540 
2541         /**
2542          * The class-only format <code>List</code> containing
2543          * <code>"java.class"</code>. This <code>List</code> is unmodifiable.
2544          *
2545          * @see #getFormats(String)
2546          */
2547         public static final List<String> FORMAT_CLASS = List.of("java.class");
2548 
2549         /**
2550          * The properties-only format <code>List</code> containing
2551          * <code>"java.properties"</code>. This <code>List</code> is unmodifiable.
2552          *
2553          * @see #getFormats(String)
2554          */
2555         public static final List<String> FORMAT_PROPERTIES
2556             = List.of("java.properties");
2557 
2558         /**
2559          * The time-to-live constant for not caching loaded resource bundle
2560          * instances.
2561          *
2562          * @see #getTimeToLive(String, Locale)
2563          */
2564         public static final long TTL_DONT_CACHE = -1;
2565 
2566         /**
2567          * The time-to-live constant for disabling the expiration control
2568          * for loaded resource bundle instances in the cache.
2569          *
2570          * @see #getTimeToLive(String, Locale)
2571          */
2572         public static final long TTL_NO_EXPIRATION_CONTROL = -2;
2573 
2574         private static final Control INSTANCE = new Control();
2575 
2576         /**
2577          * Sole constructor. (For invocation by subclass constructors,
2578          * typically implicit.)
2579          */
2580         protected Control() {
2581         }
2582 
2583         /**
2584          * Returns a <code>ResourceBundle.Control</code> in which the {@link
2585          * #getFormats(String) getFormats} method returns the specified
2586          * <code>formats</code>. The <code>formats</code> must be equal to
2587          * one of {@link Control#FORMAT_PROPERTIES}, {@link
2588          * Control#FORMAT_CLASS} or {@link
2589          * Control#FORMAT_DEFAULT}. <code>ResourceBundle.Control</code>
2590          * instances returned by this method are singletons and thread-safe.
2591          *
2592          * <p>Specifying {@link Control#FORMAT_DEFAULT} is equivalent to
2593          * instantiating the <code>ResourceBundle.Control</code> class,
2594          * except that this method returns a singleton.
2595          *
2596          * @param formats
2597          *        the formats to be returned by the
2598          *        <code>ResourceBundle.Control.getFormats</code> method
2599          * @return a <code>ResourceBundle.Control</code> supporting the
2600          *        specified <code>formats</code>
2601          * @exception NullPointerException
2602          *        if <code>formats</code> is <code>null</code>
2603          * @exception IllegalArgumentException
2604          *        if <code>formats</code> is unknown
2605          */
2606         public static final Control getControl(List<String> formats) {
2607             if (formats.equals(Control.FORMAT_PROPERTIES)) {
2608                 return SingleFormatControl.PROPERTIES_ONLY;
2609             }
2610             if (formats.equals(Control.FORMAT_CLASS)) {
2611                 return SingleFormatControl.CLASS_ONLY;
2612             }
2613             if (formats.equals(Control.FORMAT_DEFAULT)) {
2614                 return Control.INSTANCE;
2615             }
2616             throw new IllegalArgumentException();
2617         }
2618 
2619         /**
2620          * Returns a <code>ResourceBundle.Control</code> in which the {@link
2621          * #getFormats(String) getFormats} method returns the specified
2622          * <code>formats</code> and the {@link
2623          * Control#getFallbackLocale(String, Locale) getFallbackLocale}
2624          * method returns <code>null</code>. The <code>formats</code> must
2625          * be equal to one of {@link Control#FORMAT_PROPERTIES}, {@link
2626          * Control#FORMAT_CLASS} or {@link Control#FORMAT_DEFAULT}.
2627          * <code>ResourceBundle.Control</code> instances returned by this
2628          * method are singletons and thread-safe.
2629          *
2630          * @param formats
2631          *        the formats to be returned by the
2632          *        <code>ResourceBundle.Control.getFormats</code> method
2633          * @return a <code>ResourceBundle.Control</code> supporting the
2634          *        specified <code>formats</code> with no fallback
2635          *        <code>Locale</code> support
2636          * @exception NullPointerException
2637          *        if <code>formats</code> is <code>null</code>
2638          * @exception IllegalArgumentException
2639          *        if <code>formats</code> is unknown
2640          */
2641         public static final Control getNoFallbackControl(List<String> formats) {
2642             if (formats.equals(Control.FORMAT_DEFAULT)) {
2643                 return NoFallbackControl.NO_FALLBACK;
2644             }
2645             if (formats.equals(Control.FORMAT_PROPERTIES)) {
2646                 return NoFallbackControl.PROPERTIES_ONLY_NO_FALLBACK;
2647             }
2648             if (formats.equals(Control.FORMAT_CLASS)) {
2649                 return NoFallbackControl.CLASS_ONLY_NO_FALLBACK;
2650             }
2651             throw new IllegalArgumentException();
2652         }
2653 
2654         /**
2655          * Returns a <code>List</code> of <code>String</code>s containing
2656          * formats to be used to load resource bundles for the given
2657          * <code>baseName</code>. The <code>ResourceBundle.getBundle</code>
2658          * factory method tries to load resource bundles with formats in the
2659          * order specified by the list. The list returned by this method
2660          * must have at least one <code>String</code>. The predefined
2661          * formats are <code>"java.class"</code> for class-based resource
2662          * bundles and <code>"java.properties"</code> for {@linkplain
2663          * PropertyResourceBundle properties-based} ones. Strings starting
2664          * with <code>"java."</code> are reserved for future extensions and
2665          * must not be used by application-defined formats.
2666          *
2667          * <p>It is not a requirement to return an immutable (unmodifiable)
2668          * <code>List</code>.  However, the returned <code>List</code> must
2669          * not be mutated after it has been returned by
2670          * <code>getFormats</code>.
2671          *
2672          * <p>The default implementation returns {@link #FORMAT_DEFAULT} so
2673          * that the <code>ResourceBundle.getBundle</code> factory method
2674          * looks up first class-based resource bundles, then
2675          * properties-based ones.
2676          *
2677          * @param baseName
2678          *        the base name of the resource bundle, a fully qualified class
2679          *        name
2680          * @return a <code>List</code> of <code>String</code>s containing
2681          *        formats for loading resource bundles.
2682          * @exception NullPointerException
2683          *        if <code>baseName</code> is null
2684          * @see #FORMAT_DEFAULT
2685          * @see #FORMAT_CLASS
2686          * @see #FORMAT_PROPERTIES
2687          */
2688         public List<String> getFormats(String baseName) {
2689             if (baseName == null) {
2690                 throw new NullPointerException();
2691             }
2692             return FORMAT_DEFAULT;
2693         }
2694 
2695         /**
2696          * Returns a <code>List</code> of <code>Locale</code>s as candidate
2697          * locales for <code>baseName</code> and <code>locale</code>. This
2698          * method is called by the <code>ResourceBundle.getBundle</code>
2699          * factory method each time the factory method tries finding a
2700          * resource bundle for a target <code>Locale</code>.
2701          *
2702          * <p>The sequence of the candidate locales also corresponds to the
2703          * runtime resource lookup path (also known as the <I>parent
2704          * chain</I>), if the corresponding resource bundles for the
2705          * candidate locales exist and their parents are not defined by
2706          * loaded resource bundles themselves.  The last element of the list
2707          * must be a {@linkplain Locale#ROOT root locale} if it is desired to
2708          * have the base bundle as the terminal of the parent chain.
2709          *
2710          * <p>If the given locale is equal to <code>Locale.ROOT</code> (the
2711          * root locale), a <code>List</code> containing only the root
2712          * <code>Locale</code> must be returned. In this case, the
2713          * <code>ResourceBundle.getBundle</code> factory method loads only
2714          * the base bundle as the resulting resource bundle.
2715          *
2716          * <p>It is not a requirement to return an immutable (unmodifiable)
2717          * <code>List</code>. However, the returned <code>List</code> must not
2718          * be mutated after it has been returned by
2719          * <code>getCandidateLocales</code>.
2720          *
2721          * <p>The default implementation returns a <code>List</code> containing
2722          * <code>Locale</code>s using the rules described below.  In the
2723          * description below, <em>L</em>, <em>S</em>, <em>C</em> and <em>V</em>
2724          * respectively represent non-empty language, script, country, and
2725          * variant.  For example, [<em>L</em>, <em>C</em>] represents a
2726          * <code>Locale</code> that has non-empty values only for language and
2727          * country.  The form <em>L</em>("xx") represents the (non-empty)
2728          * language value is "xx".  For all cases, <code>Locale</code>s whose
2729          * final component values are empty strings are omitted.
2730          *
2731          * <ol><li>For an input <code>Locale</code> with an empty script value,
2732          * append candidate <code>Locale</code>s by omitting the final component
2733          * one by one as below:
2734          *
2735          * <ul>
2736          * <li> [<em>L</em>, <em>C</em>, <em>V</em>] </li>
2737          * <li> [<em>L</em>, <em>C</em>] </li>
2738          * <li> [<em>L</em>] </li>
2739          * <li> <code>Locale.ROOT</code> </li>
2740          * </ul></li>
2741          *
2742          * <li>For an input <code>Locale</code> with a non-empty script value,
2743          * append candidate <code>Locale</code>s by omitting the final component
2744          * up to language, then append candidates generated from the
2745          * <code>Locale</code> with country and variant restored:
2746          *
2747          * <ul>
2748          * <li> [<em>L</em>, <em>S</em>, <em>C</em>, <em>V</em>]</li>
2749          * <li> [<em>L</em>, <em>S</em>, <em>C</em>]</li>
2750          * <li> [<em>L</em>, <em>S</em>]</li>
2751          * <li> [<em>L</em>, <em>C</em>, <em>V</em>]</li>
2752          * <li> [<em>L</em>, <em>C</em>]</li>
2753          * <li> [<em>L</em>]</li>
2754          * <li> <code>Locale.ROOT</code></li>
2755          * </ul></li>
2756          *
2757          * <li>For an input <code>Locale</code> with a variant value consisting
2758          * of multiple subtags separated by underscore, generate candidate
2759          * <code>Locale</code>s by omitting the variant subtags one by one, then
2760          * insert them after every occurrence of <code> Locale</code>s with the
2761          * full variant value in the original list.  For example, if
2762          * the variant consists of two subtags <em>V1</em> and <em>V2</em>:
2763          *
2764          * <ul>
2765          * <li> [<em>L</em>, <em>S</em>, <em>C</em>, <em>V1</em>, <em>V2</em>]</li>
2766          * <li> [<em>L</em>, <em>S</em>, <em>C</em>, <em>V1</em>]</li>
2767          * <li> [<em>L</em>, <em>S</em>, <em>C</em>]</li>
2768          * <li> [<em>L</em>, <em>S</em>]</li>
2769          * <li> [<em>L</em>, <em>C</em>, <em>V1</em>, <em>V2</em>]</li>
2770          * <li> [<em>L</em>, <em>C</em>, <em>V1</em>]</li>
2771          * <li> [<em>L</em>, <em>C</em>]</li>
2772          * <li> [<em>L</em>]</li>
2773          * <li> <code>Locale.ROOT</code></li>
2774          * </ul></li>
2775          *
2776          * <li>Special cases for Chinese.  When an input <code>Locale</code> has the
2777          * language "zh" (Chinese) and an empty script value, either "Hans" (Simplified) or
2778          * "Hant" (Traditional) might be supplied, depending on the country.
2779          * When the country is "CN" (China) or "SG" (Singapore), "Hans" is supplied.
2780          * When the country is "HK" (Hong Kong SAR China), "MO" (Macau SAR China),
2781          * or "TW" (Taiwan), "Hant" is supplied.  For all other countries or when the country
2782          * is empty, no script is supplied.  For example, for <code>Locale("zh", "CN")
2783          * </code>, the candidate list will be:
2784          * <ul>
2785          * <li> [<em>L</em>("zh"), <em>S</em>("Hans"), <em>C</em>("CN")]</li>
2786          * <li> [<em>L</em>("zh"), <em>S</em>("Hans")]</li>
2787          * <li> [<em>L</em>("zh"), <em>C</em>("CN")]</li>
2788          * <li> [<em>L</em>("zh")]</li>
2789          * <li> <code>Locale.ROOT</code></li>
2790          * </ul>
2791          *
2792          * For <code>Locale("zh", "TW")</code>, the candidate list will be:
2793          * <ul>
2794          * <li> [<em>L</em>("zh"), <em>S</em>("Hant"), <em>C</em>("TW")]</li>
2795          * <li> [<em>L</em>("zh"), <em>S</em>("Hant")]</li>
2796          * <li> [<em>L</em>("zh"), <em>C</em>("TW")]</li>
2797          * <li> [<em>L</em>("zh")]</li>
2798          * <li> <code>Locale.ROOT</code></li>
2799          * </ul></li>
2800          *
2801          * <li>Special cases for Norwegian.  Both <code>Locale("no", "NO",
2802          * "NY")</code> and <code>Locale("nn", "NO")</code> represent Norwegian
2803          * Nynorsk.  When a locale's language is "nn", the standard candidate
2804          * list is generated up to [<em>L</em>("nn")], and then the following
2805          * candidates are added:
2806          *
2807          * <ul><li> [<em>L</em>("no"), <em>C</em>("NO"), <em>V</em>("NY")]</li>
2808          * <li> [<em>L</em>("no"), <em>C</em>("NO")]</li>
2809          * <li> [<em>L</em>("no")]</li>
2810          * <li> <code>Locale.ROOT</code></li>
2811          * </ul>
2812          *
2813          * If the locale is exactly <code>Locale("no", "NO", "NY")</code>, it is first
2814          * converted to <code>Locale("nn", "NO")</code> and then the above procedure is
2815          * followed.
2816          *
2817          * <p>Also, Java treats the language "no" as a synonym of Norwegian
2818          * Bokmål "nb".  Except for the single case <code>Locale("no",
2819          * "NO", "NY")</code> (handled above), when an input <code>Locale</code>
2820          * has language "no" or "nb", candidate <code>Locale</code>s with
2821          * language code "no" and "nb" are interleaved, first using the
2822          * requested language, then using its synonym. For example,
2823          * <code>Locale("nb", "NO", "POSIX")</code> generates the following
2824          * candidate list:
2825          *
2826          * <ul>
2827          * <li> [<em>L</em>("nb"), <em>C</em>("NO"), <em>V</em>("POSIX")]</li>
2828          * <li> [<em>L</em>("no"), <em>C</em>("NO"), <em>V</em>("POSIX")]</li>
2829          * <li> [<em>L</em>("nb"), <em>C</em>("NO")]</li>
2830          * <li> [<em>L</em>("no"), <em>C</em>("NO")]</li>
2831          * <li> [<em>L</em>("nb")]</li>
2832          * <li> [<em>L</em>("no")]</li>
2833          * <li> <code>Locale.ROOT</code></li>
2834          * </ul>
2835          *
2836          * <code>Locale("no", "NO", "POSIX")</code> would generate the same list
2837          * except that locales with "no" would appear before the corresponding
2838          * locales with "nb".</li>
2839          * </ol>
2840          *
2841          * <p>The default implementation uses an {@link ArrayList} that
2842          * overriding implementations may modify before returning it to the
2843          * caller. However, a subclass must not modify it after it has
2844          * been returned by <code>getCandidateLocales</code>.
2845          *
2846          * <p>For example, if the given <code>baseName</code> is "Messages"
2847          * and the given <code>locale</code> is
2848          * <code>Locale("ja",&nbsp;"",&nbsp;"XX")</code>, then a
2849          * <code>List</code> of <code>Locale</code>s:
2850          * <pre>
2851          *     Locale("ja", "", "XX")
2852          *     Locale("ja")
2853          *     Locale.ROOT
2854          * </pre>
2855          * is returned. And if the resource bundles for the "ja" and
2856          * "" <code>Locale</code>s are found, then the runtime resource
2857          * lookup path (parent chain) is:
2858          * <pre>{@code
2859          *     Messages_ja -> Messages
2860          * }</pre>
2861          *
2862          * @param baseName
2863          *        the base name of the resource bundle, a fully
2864          *        qualified class name
2865          * @param locale
2866          *        the locale for which a resource bundle is desired
2867          * @return a <code>List</code> of candidate
2868          *        <code>Locale</code>s for the given <code>locale</code>
2869          * @exception NullPointerException
2870          *        if <code>baseName</code> or <code>locale</code> is
2871          *        <code>null</code>
2872          */
2873         public List<Locale> getCandidateLocales(String baseName, Locale locale) {
2874             if (baseName == null) {
2875                 throw new NullPointerException();
2876             }
2877             return new ArrayList<>(CANDIDATES_CACHE.get(locale.getBaseLocale()));
2878         }
2879 
2880         private static final CandidateListCache CANDIDATES_CACHE = new CandidateListCache();
2881 
2882         private static class CandidateListCache extends LocaleObjectCache<BaseLocale, List<Locale>> {
2883             protected List<Locale> createObject(BaseLocale base) {
2884                 String language = base.getLanguage();
2885                 String script = base.getScript();
2886                 String region = base.getRegion();
2887                 String variant = base.getVariant();
2888 
2889                 // Special handling for Norwegian
2890                 boolean isNorwegianBokmal = false;
2891                 boolean isNorwegianNynorsk = false;
2892                 if (language.equals("no")) {
2893                     if (region.equals("NO") && variant.equals("NY")) {
2894                         variant = "";
2895                         isNorwegianNynorsk = true;
2896                     } else {
2897                         isNorwegianBokmal = true;
2898                     }
2899                 }
2900                 if (language.equals("nb") || isNorwegianBokmal) {
2901                     List<Locale> tmpList = getDefaultList("nb", script, region, variant);
2902                     // Insert a locale replacing "nb" with "no" for every list entry
2903                     List<Locale> bokmalList = new LinkedList<>();
2904                     for (Locale l : tmpList) {
2905                         bokmalList.add(l);
2906                         if (l.getLanguage().isEmpty()) {
2907                             break;
2908                         }
2909                         bokmalList.add(Locale.getInstance("no", l.getScript(), l.getCountry(),
2910                                 l.getVariant(), null));
2911                     }
2912                     return bokmalList;
2913                 } else if (language.equals("nn") || isNorwegianNynorsk) {
2914                     // Insert no_NO_NY, no_NO, no after nn
2915                     List<Locale> nynorskList = getDefaultList("nn", script, region, variant);
2916                     int idx = nynorskList.size() - 1;
2917                     nynorskList.add(idx++, Locale.getInstance("no", "NO", "NY"));
2918                     nynorskList.add(idx++, Locale.getInstance("no", "NO", ""));
2919                     nynorskList.add(idx++, Locale.getInstance("no", "", ""));
2920                     return nynorskList;
2921                 }
2922                 // Special handling for Chinese
2923                 else if (language.equals("zh")) {
2924                     if (script.isEmpty() && !region.isEmpty()) {
2925                         // Supply script for users who want to use zh_Hans/zh_Hant
2926                         // as bundle names (recommended for Java7+)
2927                         switch (region) {
2928                         case "TW":
2929                         case "HK":
2930                         case "MO":
2931                             script = "Hant";
2932                             break;
2933                         case "CN":
2934                         case "SG":
2935                             script = "Hans";
2936                             break;
2937                         }
2938                     }
2939                 }
2940 
2941                 return getDefaultList(language, script, region, variant);
2942             }
2943 
2944             private static List<Locale> getDefaultList(String language, String script, String region, String variant) {
2945                 List<String> variants = null;
2946 
2947                 if (!variant.isEmpty()) {
2948                     variants = new LinkedList<>();
2949                     int idx = variant.length();
2950                     while (idx != -1) {
2951                         variants.add(variant.substring(0, idx));
2952                         idx = variant.lastIndexOf('_', --idx);
2953                     }
2954                 }
2955 
2956                 List<Locale> list = new LinkedList<>();
2957 
2958                 if (variants != null) {
2959                     for (String v : variants) {
2960                         list.add(Locale.getInstance(language, script, region, v, null));
2961                     }
2962                 }
2963                 if (!region.isEmpty()) {
2964                     list.add(Locale.getInstance(language, script, region, "", null));
2965                 }
2966                 if (!script.isEmpty()) {
2967                     list.add(Locale.getInstance(language, script, "", "", null));
2968                     // Special handling for Chinese
2969                     if (language.equals("zh")) {
2970                         if (region.isEmpty()) {
2971                             // Supply region(country) for users who still package Chinese
2972                             // bundles using old convension.
2973                             switch (script) {
2974                                 case "Hans":
2975                                     region = "CN";
2976                                     break;
2977                                 case "Hant":
2978                                     region = "TW";
2979                                     break;
2980                             }
2981                         }
2982                     }
2983 
2984                     // With script, after truncating variant, region and script,
2985                     // start over without script.
2986                     if (variants != null) {
2987                         for (String v : variants) {
2988                             list.add(Locale.getInstance(language, "", region, v, null));
2989                         }
2990                     }
2991                     if (!region.isEmpty()) {
2992                         list.add(Locale.getInstance(language, "", region, "", null));
2993                     }
2994                 }
2995                 if (!language.isEmpty()) {
2996                     list.add(Locale.getInstance(language, "", "", "", null));
2997                 }
2998                 // Add root locale at the end
2999                 list.add(Locale.ROOT);
3000 
3001                 return list;
3002             }
3003         }
3004 
3005         /**
3006          * Returns a <code>Locale</code> to be used as a fallback locale for
3007          * further resource bundle searches by the
3008          * <code>ResourceBundle.getBundle</code> factory method. This method
3009          * is called from the factory method every time when no resulting
3010          * resource bundle has been found for <code>baseName</code> and
3011          * <code>locale</code>, where locale is either the parameter for
3012          * <code>ResourceBundle.getBundle</code> or the previous fallback
3013          * locale returned by this method.
3014          *
3015          * <p>The method returns <code>null</code> if no further fallback
3016          * search is desired.
3017          *
3018          * <p>The default implementation returns the {@linkplain
3019          * Locale#getDefault() default <code>Locale</code>} if the given
3020          * <code>locale</code> isn't the default one.  Otherwise,
3021          * <code>null</code> is returned.
3022          *
3023          * @param baseName
3024          *        the base name of the resource bundle, a fully
3025          *        qualified class name for which
3026          *        <code>ResourceBundle.getBundle</code> has been
3027          *        unable to find any resource bundles (except for the
3028          *        base bundle)
3029          * @param locale
3030          *        the <code>Locale</code> for which
3031          *        <code>ResourceBundle.getBundle</code> has been
3032          *        unable to find any resource bundles (except for the
3033          *        base bundle)
3034          * @return a <code>Locale</code> for the fallback search,
3035          *        or <code>null</code> if no further fallback search
3036          *        is desired.
3037          * @exception NullPointerException
3038          *        if <code>baseName</code> or <code>locale</code>
3039          *        is <code>null</code>
3040          */
3041         public Locale getFallbackLocale(String baseName, Locale locale) {
3042             if (baseName == null) {
3043                 throw new NullPointerException();
3044             }
3045             Locale defaultLocale = Locale.getDefault();
3046             return locale.equals(defaultLocale) ? null : defaultLocale;
3047         }
3048 
3049         /**
3050          * Instantiates a resource bundle for the given bundle name of the
3051          * given format and locale, using the given class loader if
3052          * necessary. This method returns <code>null</code> if there is no
3053          * resource bundle available for the given parameters. If a resource
3054          * bundle can't be instantiated due to an unexpected error, the
3055          * error must be reported by throwing an <code>Error</code> or
3056          * <code>Exception</code> rather than simply returning
3057          * <code>null</code>.
3058          *
3059          * <p>If the <code>reload</code> flag is <code>true</code>, it
3060          * indicates that this method is being called because the previously
3061          * loaded resource bundle has expired.
3062          *
3063          * @implSpec
3064          *
3065          * Resource bundles in named modules are subject to the encapsulation
3066          * rules specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
3067          * A resource bundle in a named module visible to the given class loader
3068          * is accessible when the package of the resource file corresponding
3069          * to the resource bundle is open unconditionally.
3070          *
3071          * <p>The default implementation instantiates a
3072          * <code>ResourceBundle</code> as follows.
3073          *
3074          * <ul>
3075          *
3076          * <li>The bundle name is obtained by calling {@link
3077          * #toBundleName(String, Locale) toBundleName(baseName,
3078          * locale)}.</li>
3079          *
3080          * <li>If <code>format</code> is <code>"java.class"</code>, the
3081          * {@link Class} specified by the bundle name is loaded with the
3082          * given class loader. If the {@code Class} is found and accessible
3083          * then the <code>ResourceBundle</code> is instantiated.  The
3084          * resource bundle is accessible if the package of the bundle class file
3085          * is open unconditionally; otherwise, {@code IllegalAccessException}
3086          * will be thrown.
3087          * Note that the <code>reload</code> flag is ignored for loading
3088          * class-based resource bundles in this default implementation.
3089          * </li>
3090          *
3091          * <li>If <code>format</code> is <code>"java.properties"</code>,
3092          * {@link #toResourceName(String, String) toResourceName(bundlename,
3093          * "properties")} is called to get the resource name.
3094          * If <code>reload</code> is <code>true</code>, {@link
3095          * ClassLoader#getResource(String) load.getResource} is called
3096          * to get a {@link URL} for creating a {@link
3097          * URLConnection}. This <code>URLConnection</code> is used to
3098          * {@linkplain URLConnection#setUseCaches(boolean) disable the
3099          * caches} of the underlying resource loading layers,
3100          * and to {@linkplain URLConnection#getInputStream() get an
3101          * <code>InputStream</code>}.
3102          * Otherwise, {@link ClassLoader#getResourceAsStream(String)
3103          * loader.getResourceAsStream} is called to get an {@link
3104          * InputStream}. Then, a {@link
3105          * PropertyResourceBundle} is constructed with the
3106          * <code>InputStream</code>.</li>
3107          *
3108          * <li>If <code>format</code> is neither <code>"java.class"</code>
3109          * nor <code>"java.properties"</code>, an
3110          * <code>IllegalArgumentException</code> is thrown.</li>
3111          *
3112          * </ul>
3113          *
3114          * @param baseName
3115          *        the base bundle name of the resource bundle, a fully
3116          *        qualified class name
3117          * @param locale
3118          *        the locale for which the resource bundle should be
3119          *        instantiated
3120          * @param format
3121          *        the resource bundle format to be loaded
3122          * @param loader
3123          *        the <code>ClassLoader</code> to use to load the bundle
3124          * @param reload
3125          *        the flag to indicate bundle reloading; <code>true</code>
3126          *        if reloading an expired resource bundle,
3127          *        <code>false</code> otherwise
3128          * @return the resource bundle instance,
3129          *        or <code>null</code> if none could be found.
3130          * @exception NullPointerException
3131          *        if <code>bundleName</code>, <code>locale</code>,
3132          *        <code>format</code>, or <code>loader</code> is
3133          *        <code>null</code>, or if <code>null</code> is returned by
3134          *        {@link #toBundleName(String, Locale) toBundleName}
3135          * @exception IllegalArgumentException
3136          *        if <code>format</code> is unknown, or if the resource
3137          *        found for the given parameters contains malformed data.
3138          * @exception ClassCastException
3139          *        if the loaded class cannot be cast to <code>ResourceBundle</code>
3140          * @exception IllegalAccessException
3141          *        if the class or its nullary constructor is not
3142          *        accessible.
3143          * @exception InstantiationException
3144          *        if the instantiation of a class fails for some other
3145          *        reason.
3146          * @exception ExceptionInInitializerError
3147          *        if the initialization provoked by this method fails.
3148          * @exception SecurityException
3149          *        If a security manager is present and creation of new
3150          *        instances is denied. See {@link Class#newInstance()}
3151          *        for details.
3152          * @exception IOException
3153          *        if an error occurred when reading resources using
3154          *        any I/O operations
3155          * @see java.util.spi.ResourceBundleProvider#getBundle(String, Locale)
3156          * @revised 9
3157          * @spec JPMS
3158          */
3159         public ResourceBundle newBundle(String baseName, Locale locale, String format,
3160                                         ClassLoader loader, boolean reload)
3161                     throws IllegalAccessException, InstantiationException, IOException {
3162             /*
3163              * Legacy mechanism to locate resource bundle in unnamed module only
3164              * that is visible to the given loader and accessible to the given caller.
3165              */
3166             String bundleName = toBundleName(baseName, locale);
3167             ResourceBundle bundle = null;
3168             if (format.equals("java.class")) {
3169                 try {
3170                     Class<?> c = loader.loadClass(bundleName);
3171                     // If the class isn't a ResourceBundle subclass, throw a
3172                     // ClassCastException.
3173                     if (ResourceBundle.class.isAssignableFrom(c)) {
3174                         @SuppressWarnings("unchecked")
3175                         Class<ResourceBundle> bundleClass = (Class<ResourceBundle>)c;
3176                         Module m = bundleClass.getModule();
3177 
3178                         // To access a resource bundle in a named module,
3179                         // either class-based or properties-based, the resource
3180                         // bundle must be opened unconditionally,
3181                         // same rule as accessing a resource file.
3182                         if (m.isNamed() && !m.isOpen(bundleClass.getPackageName())) {
3183                             throw new IllegalAccessException("unnamed module can't load " +
3184                                 bundleClass.getName() + " in " + m.toString());
3185                         }
3186                         try {
3187                             // bundle in a unnamed module
3188                             Constructor<ResourceBundle> ctor = bundleClass.getConstructor();
3189                             if (!Modifier.isPublic(ctor.getModifiers())) {
3190                                 return null;
3191                             }
3192 
3193                             // java.base may not be able to read the bundleClass's module.
3194                             PrivilegedAction<Void> pa1 = () -> { ctor.setAccessible(true); return null; };
3195                             AccessController.doPrivileged(pa1);
3196                             bundle = ctor.newInstance((Object[]) null);
3197                         } catch (InvocationTargetException e) {
3198                             uncheckedThrow(e);
3199                         }
3200                     } else {
3201                         throw new ClassCastException(c.getName()
3202                                 + " cannot be cast to ResourceBundle");
3203                     }
3204                 } catch (ClassNotFoundException|NoSuchMethodException e) {
3205                 }
3206             } else if (format.equals("java.properties")) {
3207                 final String resourceName = toResourceName0(bundleName, "properties");
3208                 if (resourceName == null) {
3209                     return bundle;
3210                 }
3211 
3212                 final boolean reloadFlag = reload;
3213                 InputStream stream = null;
3214                 try {
3215                     stream = AccessController.doPrivileged(
3216                         new PrivilegedExceptionAction<>() {
3217                             public InputStream run() throws IOException {
3218                                 URL url = loader.getResource(resourceName);
3219                                 if (url == null) return null;
3220 
3221                                 URLConnection connection = url.openConnection();
3222                                 if (reloadFlag) {
3223                                     // Disable caches to get fresh data for
3224                                     // reloading.
3225                                     connection.setUseCaches(false);
3226                                 }
3227                                 return connection.getInputStream();
3228                             }
3229                         });
3230                 } catch (PrivilegedActionException e) {
3231                     throw (IOException) e.getException();
3232                 }
3233                 if (stream != null) {
3234                     try {
3235                         bundle = new PropertyResourceBundle(stream);
3236                     } finally {
3237                         stream.close();
3238                     }
3239                 }
3240             } else {
3241                 throw new IllegalArgumentException("unknown format: " + format);
3242             }
3243             return bundle;
3244         }
3245 
3246         /**
3247          * Returns the time-to-live (TTL) value for resource bundles that
3248          * are loaded under this
3249          * <code>ResourceBundle.Control</code>. Positive time-to-live values
3250          * specify the number of milliseconds a bundle can remain in the
3251          * cache without being validated against the source data from which
3252          * it was constructed. The value 0 indicates that a bundle must be
3253          * validated each time it is retrieved from the cache. {@link
3254          * #TTL_DONT_CACHE} specifies that loaded resource bundles are not
3255          * put in the cache. {@link #TTL_NO_EXPIRATION_CONTROL} specifies
3256          * that loaded resource bundles are put in the cache with no
3257          * expiration control.
3258          *
3259          * <p>The expiration affects only the bundle loading process by the
3260          * <code>ResourceBundle.getBundle</code> factory method.  That is,
3261          * if the factory method finds a resource bundle in the cache that
3262          * has expired, the factory method calls the {@link
3263          * #needsReload(String, Locale, String, ClassLoader, ResourceBundle,
3264          * long) needsReload} method to determine whether the resource
3265          * bundle needs to be reloaded. If <code>needsReload</code> returns
3266          * <code>true</code>, the cached resource bundle instance is removed
3267          * from the cache. Otherwise, the instance stays in the cache,
3268          * updated with the new TTL value returned by this method.
3269          *
3270          * <p>All cached resource bundles are subject to removal from the
3271          * cache due to memory constraints of the runtime environment.
3272          * Returning a large positive value doesn't mean to lock loaded
3273          * resource bundles in the cache.
3274          *
3275          * <p>The default implementation returns {@link #TTL_NO_EXPIRATION_CONTROL}.
3276          *
3277          * @param baseName
3278          *        the base name of the resource bundle for which the
3279          *        expiration value is specified.
3280          * @param locale
3281          *        the locale of the resource bundle for which the
3282          *        expiration value is specified.
3283          * @return the time (0 or a positive millisecond offset from the
3284          *        cached time) to get loaded bundles expired in the cache,
3285          *        {@link #TTL_NO_EXPIRATION_CONTROL} to disable the
3286          *        expiration control, or {@link #TTL_DONT_CACHE} to disable
3287          *        caching.
3288          * @exception NullPointerException
3289          *        if <code>baseName</code> or <code>locale</code> is
3290          *        <code>null</code>
3291          */
3292         public long getTimeToLive(String baseName, Locale locale) {
3293             if (baseName == null || locale == null) {
3294                 throw new NullPointerException();
3295             }
3296             return TTL_NO_EXPIRATION_CONTROL;
3297         }
3298 
3299         /**
3300          * Determines if the expired <code>bundle</code> in the cache needs
3301          * to be reloaded based on the loading time given by
3302          * <code>loadTime</code> or some other criteria. The method returns
3303          * <code>true</code> if reloading is required; <code>false</code>
3304          * otherwise. <code>loadTime</code> is a millisecond offset since
3305          * the <a href="Calendar.html#Epoch"> <code>Calendar</code>
3306          * Epoch</a>.
3307          *
3308          * <p>
3309          * The calling <code>ResourceBundle.getBundle</code> factory method
3310          * calls this method on the <code>ResourceBundle.Control</code>
3311          * instance used for its current invocation, not on the instance
3312          * used in the invocation that originally loaded the resource
3313          * bundle.
3314          *
3315          * <p>The default implementation compares <code>loadTime</code> and
3316          * the last modified time of the source data of the resource
3317          * bundle. If it's determined that the source data has been modified
3318          * since <code>loadTime</code>, <code>true</code> is
3319          * returned. Otherwise, <code>false</code> is returned. This
3320          * implementation assumes that the given <code>format</code> is the
3321          * same string as its file suffix if it's not one of the default
3322          * formats, <code>"java.class"</code> or
3323          * <code>"java.properties"</code>.
3324          *
3325          * @param baseName
3326          *        the base bundle name of the resource bundle, a
3327          *        fully qualified class name
3328          * @param locale
3329          *        the locale for which the resource bundle
3330          *        should be instantiated
3331          * @param format
3332          *        the resource bundle format to be loaded
3333          * @param loader
3334          *        the <code>ClassLoader</code> to use to load the bundle
3335          * @param bundle
3336          *        the resource bundle instance that has been expired
3337          *        in the cache
3338          * @param loadTime
3339          *        the time when <code>bundle</code> was loaded and put
3340          *        in the cache
3341          * @return <code>true</code> if the expired bundle needs to be
3342          *        reloaded; <code>false</code> otherwise.
3343          * @exception NullPointerException
3344          *        if <code>baseName</code>, <code>locale</code>,
3345          *        <code>format</code>, <code>loader</code>, or
3346          *        <code>bundle</code> is <code>null</code>
3347          */
3348         public boolean needsReload(String baseName, Locale locale,
3349                                    String format, ClassLoader loader,
3350                                    ResourceBundle bundle, long loadTime) {
3351             if (bundle == null) {
3352                 throw new NullPointerException();
3353             }
3354             if (format.equals("java.class") || format.equals("java.properties")) {
3355                 format = format.substring(5);
3356             }
3357             boolean result = false;
3358             try {
3359                 String resourceName = toResourceName0(toBundleName(baseName, locale), format);
3360                 if (resourceName == null) {
3361                     return result;
3362                 }
3363                 URL url = loader.getResource(resourceName);
3364                 if (url != null) {
3365                     long lastModified = 0;
3366                     URLConnection connection = url.openConnection();
3367                     if (connection != null) {
3368                         // disable caches to get the correct data
3369                         connection.setUseCaches(false);
3370                         if (connection instanceof JarURLConnection) {
3371                             JarEntry ent = ((JarURLConnection)connection).getJarEntry();
3372                             if (ent != null) {
3373                                 lastModified = ent.getTime();
3374                                 if (lastModified == -1) {
3375                                     lastModified = 0;
3376                                 }
3377                             }
3378                         } else {
3379                             lastModified = connection.getLastModified();
3380                         }
3381                     }
3382                     result = lastModified >= loadTime;
3383                 }
3384             } catch (NullPointerException npe) {
3385                 throw npe;
3386             } catch (Exception e) {
3387                 // ignore other exceptions
3388             }
3389             return result;
3390         }
3391 
3392         /**
3393          * Converts the given <code>baseName</code> and <code>locale</code>
3394          * to the bundle name. This method is called from the default
3395          * implementation of the {@link #newBundle(String, Locale, String,
3396          * ClassLoader, boolean) newBundle} and {@link #needsReload(String,
3397          * Locale, String, ClassLoader, ResourceBundle, long) needsReload}
3398          * methods.
3399          *
3400          * <p>This implementation returns the following value:
3401          * <pre>
3402          *     baseName + "_" + language + "_" + script + "_" + country + "_" + variant
3403          * </pre>
3404          * where <code>language</code>, <code>script</code>, <code>country</code>,
3405          * and <code>variant</code> are the language, script, country, and variant
3406          * values of <code>locale</code>, respectively. Final component values that
3407          * are empty Strings are omitted along with the preceding '_'.  When the
3408          * script is empty, the script value is omitted along with the preceding '_'.
3409          * If all of the values are empty strings, then <code>baseName</code>
3410          * is returned.
3411          *
3412          * <p>For example, if <code>baseName</code> is
3413          * <code>"baseName"</code> and <code>locale</code> is
3414          * <code>Locale("ja",&nbsp;"",&nbsp;"XX")</code>, then
3415          * <code>"baseName_ja_&thinsp;_XX"</code> is returned. If the given
3416          * locale is <code>Locale("en")</code>, then
3417          * <code>"baseName_en"</code> is returned.
3418          *
3419          * <p>Overriding this method allows applications to use different
3420          * conventions in the organization and packaging of localized
3421          * resources.
3422          *
3423          * @param baseName
3424          *        the base name of the resource bundle, a fully
3425          *        qualified class name
3426          * @param locale
3427          *        the locale for which a resource bundle should be
3428          *        loaded
3429          * @return the bundle name for the resource bundle
3430          * @exception NullPointerException
3431          *        if <code>baseName</code> or <code>locale</code>
3432          *        is <code>null</code>
3433          * @see java.util.spi.AbstractResourceBundleProvider#toBundleName(String, Locale)
3434          */
3435         public String toBundleName(String baseName, Locale locale) {
3436             if (locale == Locale.ROOT) {
3437                 return baseName;
3438             }
3439 
3440             String language = locale.getLanguage();
3441             String script = locale.getScript();
3442             String country = locale.getCountry();
3443             String variant = locale.getVariant();
3444 
3445             if (language == "" && country == "" && variant == "") {
3446                 return baseName;
3447             }
3448 
3449             StringBuilder sb = new StringBuilder(baseName);
3450             sb.append('_');
3451             if (script != "") {
3452                 if (variant != "") {
3453                     sb.append(language).append('_').append(script).append('_').append(country).append('_').append(variant);
3454                 } else if (country != "") {
3455                     sb.append(language).append('_').append(script).append('_').append(country);
3456                 } else {
3457                     sb.append(language).append('_').append(script);
3458                 }
3459             } else {
3460                 if (variant != "") {
3461                     sb.append(language).append('_').append(country).append('_').append(variant);
3462                 } else if (country != "") {
3463                     sb.append(language).append('_').append(country);
3464                 } else {
3465                     sb.append(language);
3466                 }
3467             }
3468             return sb.toString();
3469 
3470         }
3471 
3472         /**
3473          * Converts the given {@code bundleName} to the form required
3474          * by the {@link ClassLoader#getResource ClassLoader.getResource}
3475          * method by replacing all occurrences of {@code '.'} in
3476          * {@code bundleName} with {@code '/'} and appending a
3477          * {@code '.'} and the given file {@code suffix}. For
3478          * example, if {@code bundleName} is
3479          * {@code "foo.bar.MyResources_ja_JP"} and {@code suffix}
3480          * is {@code "properties"}, then
3481          * {@code "foo/bar/MyResources_ja_JP.properties"} is returned.
3482          *
3483          * @param bundleName
3484          *        the bundle name
3485          * @param suffix
3486          *        the file type suffix
3487          * @return the converted resource name
3488          * @exception NullPointerException
3489          *         if {@code bundleName} or {@code suffix}
3490          *         is {@code null}
3491          */
3492         public final String toResourceName(String bundleName, String suffix) {
3493             StringBuilder sb = new StringBuilder(bundleName.length() + 1 + suffix.length());
3494             sb.append(bundleName.replace('.', '/')).append('.').append(suffix);
3495             return sb.toString();
3496         }
3497 
3498         private String toResourceName0(String bundleName, String suffix) {
3499             // application protocol check
3500             if (bundleName.contains("://")) {
3501                 return null;
3502             } else {
3503                 return toResourceName(bundleName, suffix);
3504             }
3505         }
3506     }
3507 
3508     @SuppressWarnings("unchecked")
3509     private static <T extends Throwable> void uncheckedThrow(Throwable t) throws T {
3510         if (t != null)
3511             throw (T)t;
3512         else
3513             throw new Error("Unknown Exception");
3514     }
3515 
3516     private static class SingleFormatControl extends Control {
3517         private static final Control PROPERTIES_ONLY
3518             = new SingleFormatControl(FORMAT_PROPERTIES);
3519 
3520         private static final Control CLASS_ONLY
3521             = new SingleFormatControl(FORMAT_CLASS);
3522 
3523         private final List<String> formats;
3524 
3525         protected SingleFormatControl(List<String> formats) {
3526             this.formats = formats;
3527         }
3528 
3529         public List<String> getFormats(String baseName) {
3530             if (baseName == null) {
3531                 throw new NullPointerException();
3532             }
3533             return formats;
3534         }
3535     }
3536 
3537     private static final class NoFallbackControl extends SingleFormatControl {
3538         private static final Control NO_FALLBACK
3539             = new NoFallbackControl(FORMAT_DEFAULT);
3540 
3541         private static final Control PROPERTIES_ONLY_NO_FALLBACK
3542             = new NoFallbackControl(FORMAT_PROPERTIES);
3543 
3544         private static final Control CLASS_ONLY_NO_FALLBACK
3545             = new NoFallbackControl(FORMAT_CLASS);
3546 
3547         protected NoFallbackControl(List<String> formats) {
3548             super(formats);
3549         }
3550 
3551         public Locale getFallbackLocale(String baseName, Locale locale) {
3552             if (baseName == null || locale == null) {
3553                 throw new NullPointerException();
3554             }
3555             return null;
3556         }
3557     }
3558 
3559     private static class ResourceBundleProviderHelper {
3560         /**
3561          * Returns a new ResourceBundle instance of the given bundleClass
3562          */
3563         static ResourceBundle newResourceBundle(Class<? extends ResourceBundle> bundleClass) {
3564             try {
3565                 @SuppressWarnings("unchecked")
3566                 Constructor<? extends ResourceBundle> ctor =
3567                     bundleClass.getConstructor();
3568                 if (!Modifier.isPublic(ctor.getModifiers())) {
3569                     return null;
3570                 }
3571                 // java.base may not be able to read the bundleClass's module.
3572                 PrivilegedAction<Void> pa = () -> { ctor.setAccessible(true); return null;};
3573                 AccessController.doPrivileged(pa);
3574                 try {
3575                     return ctor.newInstance((Object[]) null);
3576                 } catch (InvocationTargetException e) {
3577                     uncheckedThrow(e);
3578                 } catch (InstantiationException | IllegalAccessException e) {
3579                     throw new InternalError(e);
3580                 }
3581             } catch (NoSuchMethodException e) {
3582                 throw new InternalError(e);
3583             }
3584             return null;
3585         }
3586 
3587         /**
3588          * Loads a {@code ResourceBundle} of the given {@code bundleName} local to
3589          * the given {@code module}. If not found, search the bundle class
3590          * that is visible from the module's class loader.
3591          *
3592          * The caller module is used for access check only.
3593          */
3594         static ResourceBundle loadResourceBundle(Module callerModule,
3595                                                  Module module,
3596                                                  String baseName,
3597                                                  Locale locale)
3598         {
3599             String bundleName = Control.INSTANCE.toBundleName(baseName, locale);
3600             try {
3601                 PrivilegedAction<Class<?>> pa = () -> Class.forName(module, bundleName);
3602                 Class<?> c = AccessController.doPrivileged(pa, null, GET_CLASSLOADER_PERMISSION);
3603                 trace("local in %s %s caller %s: %s%n", module, bundleName, callerModule, c);
3604 
3605                 if (c == null) {
3606                     // if not found from the given module, locate resource bundle
3607                     // that is visible to the module's class loader
3608                     ClassLoader loader = getLoader(module);
3609                     if (loader != null) {
3610                         c = Class.forName(bundleName, false, loader);
3611                     } else {
3612                         c = BootLoader.loadClassOrNull(bundleName);
3613                     }
3614                     trace("loader for %s %s caller %s: %s%n", module, bundleName, callerModule, c);
3615                 }
3616 
3617                 if (c != null && ResourceBundle.class.isAssignableFrom(c)) {
3618                     @SuppressWarnings("unchecked")
3619                     Class<ResourceBundle> bundleClass = (Class<ResourceBundle>) c;
3620                     Module m = bundleClass.getModule();
3621                     if (!isAccessible(callerModule, m, bundleClass.getPackageName())) {
3622                         trace("   %s does not have access to %s/%s%n", callerModule,
3623                               m.getName(), bundleClass.getPackageName());
3624                         return null;
3625                     }
3626 
3627                     return newResourceBundle(bundleClass);
3628                 }
3629             } catch (ClassNotFoundException e) {}
3630             return null;
3631         }
3632 
3633         /**
3634          * Tests if resources of the given package name from the given module are
3635          * open to the caller module.
3636          */
3637         static boolean isAccessible(Module callerModule, Module module, String pn) {
3638             if (!module.isNamed() || callerModule == module)
3639                 return true;
3640 
3641             return module.isOpen(pn, callerModule);
3642         }
3643 
3644         /**
3645          * Loads properties of the given {@code bundleName} local in the given
3646          * {@code module}.  If the .properties is not found or not open
3647          * to the caller module to access, it will find the resource that
3648          * is visible to the module's class loader.
3649          *
3650          * The caller module is used for access check only.
3651          */
3652         static ResourceBundle loadPropertyResourceBundle(Module callerModule,
3653                                                          Module module,
3654                                                          String baseName,
3655                                                          Locale locale)
3656             throws IOException
3657         {
3658             String bundleName = Control.INSTANCE.toBundleName(baseName, locale);
3659 
3660             PrivilegedAction<InputStream> pa = () -> {
3661                 try {
3662                     String resourceName = Control.INSTANCE
3663                         .toResourceName0(bundleName, "properties");
3664                     if (resourceName == null) {
3665                         return null;
3666                     }
3667                     trace("local in %s %s caller %s%n", module, resourceName, callerModule);
3668 
3669                     // if the package is in the given module but not opened
3670                     // locate it from the given module first.
3671                     String pn = toPackageName(bundleName);
3672                     trace("   %s/%s is accessible to %s : %s%n",
3673                             module.getName(), pn, callerModule,
3674                             isAccessible(callerModule, module, pn));
3675                     if (isAccessible(callerModule, module, pn)) {
3676                         InputStream in = module.getResourceAsStream(resourceName);
3677                         if (in != null) {
3678                             return in;
3679                         }
3680                     }
3681 
3682                     ClassLoader loader = module.getClassLoader();
3683                     trace("loader for %s %s caller %s%n", module, resourceName, callerModule);
3684 
3685                     try {
3686                         if (loader != null) {
3687                             return loader.getResourceAsStream(resourceName);
3688                         } else {
3689                             URL url = BootLoader.findResource(resourceName);
3690                             if (url != null) {
3691                                 return url.openStream();
3692                             }
3693                         }
3694                     } catch (Exception e) {}
3695                     return null;
3696 
3697                 } catch (IOException e) {
3698                     throw new UncheckedIOException(e);
3699                 }
3700             };
3701 
3702             try (InputStream stream = AccessController.doPrivileged(pa)) {
3703                 if (stream != null) {
3704                     return new PropertyResourceBundle(stream);
3705                 } else {
3706                     return null;
3707                 }
3708             } catch (UncheckedIOException e) {
3709                 throw e.getCause();
3710             }
3711         }
3712 
3713         private static String toPackageName(String bundleName) {
3714             int i = bundleName.lastIndexOf('.');
3715             return i != -1 ? bundleName.substring(0, i) : "";
3716         }
3717 
3718     }
3719 
3720     private static final boolean TRACE_ON = Boolean.valueOf(
3721         GetPropertyAction.privilegedGetProperty("resource.bundle.debug", "false"));
3722 
3723     private static void trace(String format, Object... params) {
3724         if (TRACE_ON)
3725             System.out.format(format, params);
3726     }
3727 }