1 /*
   2  * Copyright (c) 1996, 2017, 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 - All Rights Reserved
  28  * (C) Copyright IBM Corp. 1996 - All Rights Reserved
  29  *
  30  *   The original version of this source code and documentation is copyrighted
  31  * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
  32  * materials are provided under terms of a License Agreement between Taligent
  33  * and Sun. This technology is protected by multiple US and International
  34  * patents. This notice and attribution to Taligent may not be removed.
  35  *   Taligent is a registered trademark of Taligent, Inc.
  36  *
  37  */
  38 
  39 package java.text;
  40 
  41 import java.io.InvalidObjectException;
  42 import java.text.spi.DateFormatProvider;
  43 import java.util.Calendar;
  44 import java.util.Date;
  45 import java.util.GregorianCalendar;
  46 import java.util.HashMap;
  47 import java.util.Locale;
  48 import java.util.Map;
  49 import java.util.MissingResourceException;
  50 import java.util.ResourceBundle;
  51 import java.util.TimeZone;
  52 import java.util.spi.LocaleServiceProvider;
  53 import sun.util.locale.provider.LocaleProviderAdapter;
  54 import sun.util.locale.provider.LocaleServiceProviderPool;
  55 
  56 /**
  57  * {@code DateFormat} is an abstract class for date/time formatting subclasses which
  58  * formats and parses dates or time in a language-independent manner.
  59  * The date/time formatting subclass, such as {@link SimpleDateFormat}, allows for
  60  * formatting (i.e., date → text), parsing (text → date), and
  61  * normalization.  The date is represented as a <code>Date</code> object or
  62  * as the milliseconds since January 1, 1970, 00:00:00 GMT.
  63  *
  64  * <p>{@code DateFormat} provides many class methods for obtaining default date/time
  65  * formatters based on the default or a given locale and a number of formatting
  66  * styles. The formatting styles include {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, and {@link #SHORT}. More
  67  * detail and examples of using these styles are provided in the method
  68  * descriptions.
  69  *
  70  * <p>{@code DateFormat} helps you to format and parse dates for any locale.
  71  * Your code can be completely independent of the locale conventions for
  72  * months, days of the week, or even the calendar format: lunar vs. solar.
  73  *
  74  * <p>To format a date for the current Locale, use one of the
  75  * static factory methods:
  76  * <blockquote>
  77  * <pre>{@code
  78  * myString = DateFormat.getDateInstance().format(myDate);
  79  * }</pre>
  80  * </blockquote>
  81  * <p>If you are formatting multiple dates, it is
  82  * more efficient to get the format and use it multiple times so that
  83  * the system doesn't have to fetch the information about the local
  84  * language and country conventions multiple times.
  85  * <blockquote>
  86  * <pre>{@code
  87  * DateFormat df = DateFormat.getDateInstance();
  88  * for (int i = 0; i < myDate.length; ++i) {
  89  *     output.println(df.format(myDate[i]) + "; ");
  90  * }
  91  * }</pre>
  92  * </blockquote>
  93  * <p>To format a date for a different Locale, specify it in the
  94  * call to {@link #getDateInstance(int, Locale) getDateInstance()}.
  95  * <blockquote>
  96  * <pre>{@code
  97  * DateFormat df = DateFormat.getDateInstance(DateFormat.LONG, Locale.FRANCE);
  98  * }</pre>
  99  * </blockquote>
 100  * <p>You can use a DateFormat to parse also.
 101  * <blockquote>
 102  * <pre>{@code
 103  * myDate = df.parse(myString);
 104  * }</pre>
 105  * </blockquote>
 106  * <p>Use {@code getDateInstance} to get the normal date format for that country.
 107  * There are other static factory methods available.
 108  * Use {@code getTimeInstance} to get the time format for that country.
 109  * Use {@code getDateTimeInstance} to get a date and time format. You can pass in
 110  * different options to these factory methods to control the length of the
 111  * result; from {@link #SHORT} to {@link #MEDIUM} to {@link #LONG} to {@link #FULL}. The exact result depends
 112  * on the locale, but generally:
 113  * <ul><li>{@link #SHORT} is completely numeric, such as {@code 12.13.52} or {@code 3:30pm}
 114  * <li>{@link #MEDIUM} is longer, such as {@code Jan 12, 1952}
 115  * <li>{@link #LONG} is longer, such as {@code January 12, 1952} or {@code 3:30:32pm}
 116  * <li>{@link #FULL} is pretty completely specified, such as
 117  * {@code Tuesday, April 12, 1952 AD or 3:30:42pm PST}.
 118  * </ul>
 119  *
 120  * <p>You can also set the time zone on the format if you wish.
 121  * If you want even more control over the format or parsing,
 122  * (or want to give your users more control),
 123  * you can try casting the {@code DateFormat} you get from the factory methods
 124  * to a {@link SimpleDateFormat}. This will work for the majority
 125  * of countries; just remember to put it in a {@code try} block in case you
 126  * encounter an unusual one.
 127  *
 128  * <p>You can also use forms of the parse and format methods with
 129  * {@link ParsePosition} and {@link FieldPosition} to
 130  * allow you to
 131  * <ul><li>progressively parse through pieces of a string.
 132  * <li>align any particular field, or find out where it is for selection
 133  * on the screen.
 134  * </ul>
 135  *
 136  * <h3><a id="synchronization">Synchronization</a></h3>
 137  *
 138  * <p>
 139  * Date formats are not synchronized.
 140  * It is recommended to create separate format instances for each thread.
 141  * If multiple threads access a format concurrently, it must be synchronized
 142  * externally.
 143  *
 144  * @implSpec
 145  * <ul><li>The {@link #format(Date, StringBuffer, FieldPosition)} and
 146  * {@link #parse(String, ParsePosition)} methods may throw
 147  * {@code NullPointerException}, if any of their parameter is {@code null}.
 148  * The subclass may provide its own implementation and specification about
 149  * {@code NullPointerException}.</li>
 150  * <li>The {@link #setCalendar(Calendar)}, {@link
 151  * #setNumberFormat(NumberFormat)} and {@link #setTimeZone(TimeZone)} methods
 152  * do not throw {@code NullPointerException} when their parameter is
 153  * {@code null}, but any subsequent operations on the same instance may throw
 154  * {@code NullPointerException}.</li>
 155  * <li>The {@link #getCalendar()}, {@link #getNumberFormat()} and
 156  * {@link getTimeZone()} methods may return {@code null}, if the respective
 157  * values of this instance is set to {@code null} through the corresponding
 158  * setter methods. For Example: {@link #getTimeZone()} may return {@code null},
 159  * if the {@code TimeZone} value of this instance is set as
 160  * {@link #setTimeZone(java.util.TimeZone) setTimeZone(null)}.</li>
 161  * </ul>
 162  *
 163  * @see          Format
 164  * @see          NumberFormat
 165  * @see          SimpleDateFormat
 166  * @see          java.util.Calendar
 167  * @see          java.util.GregorianCalendar
 168  * @see          java.util.TimeZone
 169  * @author       Mark Davis, Chen-Lieh Huang, Alan Liu
 170  * @since 1.1
 171  */
 172 public abstract class DateFormat extends Format {
 173 
 174     /**
 175      * The {@link Calendar} instance used for calculating the date-time fields
 176      * and the instant of time. This field is used for both formatting and
 177      * parsing.
 178      *
 179      * <p>Subclasses should initialize this field to a {@link Calendar}
 180      * appropriate for the {@link Locale} associated with this
 181      * <code>DateFormat</code>.
 182      * @serial
 183      */
 184     protected Calendar calendar;
 185 
 186     /**
 187      * The number formatter that <code>DateFormat</code> uses to format numbers
 188      * in dates and times.  Subclasses should initialize this to a number format
 189      * appropriate for the locale associated with this <code>DateFormat</code>.
 190      * @serial
 191      */
 192     protected NumberFormat numberFormat;
 193 
 194     /**
 195      * Useful constant for ERA field alignment.
 196      * Used in FieldPosition of date/time formatting.
 197      */
 198     public static final int ERA_FIELD = 0;
 199     /**
 200      * Useful constant for YEAR field alignment.
 201      * Used in FieldPosition of date/time formatting.
 202      */
 203     public static final int YEAR_FIELD = 1;
 204     /**
 205      * Useful constant for MONTH field alignment.
 206      * Used in FieldPosition of date/time formatting.
 207      */
 208     public static final int MONTH_FIELD = 2;
 209     /**
 210      * Useful constant for DATE field alignment.
 211      * Used in FieldPosition of date/time formatting.
 212      */
 213     public static final int DATE_FIELD = 3;
 214     /**
 215      * Useful constant for one-based HOUR_OF_DAY field alignment.
 216      * Used in FieldPosition of date/time formatting.
 217      * HOUR_OF_DAY1_FIELD is used for the one-based 24-hour clock.
 218      * For example, 23:59 + 01:00 results in 24:59.
 219      */
 220     public static final int HOUR_OF_DAY1_FIELD = 4;
 221     /**
 222      * Useful constant for zero-based HOUR_OF_DAY field alignment.
 223      * Used in FieldPosition of date/time formatting.
 224      * HOUR_OF_DAY0_FIELD is used for the zero-based 24-hour clock.
 225      * For example, 23:59 + 01:00 results in 00:59.
 226      */
 227     public static final int HOUR_OF_DAY0_FIELD = 5;
 228     /**
 229      * Useful constant for MINUTE field alignment.
 230      * Used in FieldPosition of date/time formatting.
 231      */
 232     public static final int MINUTE_FIELD = 6;
 233     /**
 234      * Useful constant for SECOND field alignment.
 235      * Used in FieldPosition of date/time formatting.
 236      */
 237     public static final int SECOND_FIELD = 7;
 238     /**
 239      * Useful constant for MILLISECOND field alignment.
 240      * Used in FieldPosition of date/time formatting.
 241      */
 242     public static final int MILLISECOND_FIELD = 8;
 243     /**
 244      * Useful constant for DAY_OF_WEEK field alignment.
 245      * Used in FieldPosition of date/time formatting.
 246      */
 247     public static final int DAY_OF_WEEK_FIELD = 9;
 248     /**
 249      * Useful constant for DAY_OF_YEAR field alignment.
 250      * Used in FieldPosition of date/time formatting.
 251      */
 252     public static final int DAY_OF_YEAR_FIELD = 10;
 253     /**
 254      * Useful constant for DAY_OF_WEEK_IN_MONTH field alignment.
 255      * Used in FieldPosition of date/time formatting.
 256      */
 257     public static final int DAY_OF_WEEK_IN_MONTH_FIELD = 11;
 258     /**
 259      * Useful constant for WEEK_OF_YEAR field alignment.
 260      * Used in FieldPosition of date/time formatting.
 261      */
 262     public static final int WEEK_OF_YEAR_FIELD = 12;
 263     /**
 264      * Useful constant for WEEK_OF_MONTH field alignment.
 265      * Used in FieldPosition of date/time formatting.
 266      */
 267     public static final int WEEK_OF_MONTH_FIELD = 13;
 268     /**
 269      * Useful constant for AM_PM field alignment.
 270      * Used in FieldPosition of date/time formatting.
 271      */
 272     public static final int AM_PM_FIELD = 14;
 273     /**
 274      * Useful constant for one-based HOUR field alignment.
 275      * Used in FieldPosition of date/time formatting.
 276      * HOUR1_FIELD is used for the one-based 12-hour clock.
 277      * For example, 11:30 PM + 1 hour results in 12:30 AM.
 278      */
 279     public static final int HOUR1_FIELD = 15;
 280     /**
 281      * Useful constant for zero-based HOUR field alignment.
 282      * Used in FieldPosition of date/time formatting.
 283      * HOUR0_FIELD is used for the zero-based 12-hour clock.
 284      * For example, 11:30 PM + 1 hour results in 00:30 AM.
 285      */
 286     public static final int HOUR0_FIELD = 16;
 287     /**
 288      * Useful constant for TIMEZONE field alignment.
 289      * Used in FieldPosition of date/time formatting.
 290      */
 291     public static final int TIMEZONE_FIELD = 17;
 292 
 293     // Proclaim serial compatibility with 1.1 FCS
 294     private static final long serialVersionUID = 7218322306649953788L;
 295 
 296     /**
 297      * Formats the given {@code Object} into a date-time string. The formatted
 298      * string is appended to the given {@code StringBuffer}.
 299      *
 300      * @param obj Must be a {@code Date} or a {@code Number} representing a
 301      * millisecond offset from the <a href="../util/Calendar.html#Epoch">Epoch</a>.
 302      * @param toAppendTo The string buffer for the returning date-time string.
 303      * @param fieldPosition keeps track on the position of the field within
 304      * the returned string. For example, given a date-time text
 305      * {@code "1996.07.10 AD at 15:08:56 PDT"}, if the given {@code fieldPosition}
 306      * is {@link DateFormat#YEAR_FIELD}, the begin index and end index of
 307      * {@code fieldPosition} will be set to 0 and 4, respectively.
 308      * Notice that if the same date-time field appears more than once in a
 309      * pattern, the {@code fieldPosition} will be set for the first occurrence
 310      * of that date-time field. For instance, formatting a {@code Date} to the
 311      * date-time string {@code "1 PM PDT (Pacific Daylight Time)"} using the
 312      * pattern {@code "h a z (zzzz)"} and the alignment field
 313      * {@link DateFormat#TIMEZONE_FIELD}, the begin index and end index of
 314      * {@code fieldPosition} will be set to 5 and 8, respectively, for the
 315      * first occurrence of the timezone pattern character {@code 'z'}.
 316      * @return the string buffer passed in as {@code toAppendTo},
 317      *         with formatted text appended.
 318      * @exception IllegalArgumentException if the {@code Format} cannot format
 319      *         the given {@code obj}.
 320      * @see java.text.Format
 321      */
 322     public final StringBuffer format(Object obj, StringBuffer toAppendTo,
 323                                      FieldPosition fieldPosition)
 324     {
 325         if (obj instanceof Date)
 326             return format( (Date)obj, toAppendTo, fieldPosition );
 327         else if (obj instanceof Number)
 328             return format( new Date(((Number)obj).longValue()),
 329                           toAppendTo, fieldPosition );
 330         else
 331             throw new IllegalArgumentException("Cannot format given Object as a Date");
 332     }
 333 
 334     /**
 335      * Formats a {@link Date} into a date-time string. The formatted
 336      * string is appended to the given {@code StringBuffer}.
 337      *
 338      * @param date a Date to be formatted into a date-time string.
 339      * @param toAppendTo the string buffer for the returning date-time string.
 340      * @param fieldPosition keeps track on the position of the field within
 341      * the returned string. For example, given a date-time text
 342      * {@code "1996.07.10 AD at 15:08:56 PDT"}, if the given {@code fieldPosition}
 343      * is {@link DateFormat#YEAR_FIELD}, the begin index and end index of
 344      * {@code fieldPosition} will be set to 0 and 4, respectively.
 345      * Notice that if the same date-time field appears more than once in a
 346      * pattern, the {@code fieldPosition} will be set for the first occurrence
 347      * of that date-time field. For instance, formatting a {@code Date} to the
 348      * date-time string {@code "1 PM PDT (Pacific Daylight Time)"} using the
 349      * pattern {@code "h a z (zzzz)"} and the alignment field
 350      * {@link DateFormat#TIMEZONE_FIELD}, the begin index and end index of
 351      * {@code fieldPosition} will be set to 5 and 8, respectively, for the
 352      * first occurrence of the timezone pattern character {@code 'z'}.
 353      * @return the string buffer passed in as {@code toAppendTo}, with formatted
 354      * text appended.
 355      */
 356     public abstract StringBuffer format(Date date, StringBuffer toAppendTo,
 357                                         FieldPosition fieldPosition);
 358 
 359     /**
 360       * Formats a {@link Date} into a date-time string.
 361       *
 362       * @param date the time value to be formatted into a date-time string.
 363       * @return the formatted date-time string.
 364      */
 365     public final String format(Date date)
 366     {
 367         return format(date, new StringBuffer(),
 368                       DontCareFieldPosition.INSTANCE).toString();
 369     }
 370 
 371     /**
 372      * Parses text from the beginning of the given string to produce a date.
 373      * The method may not use the entire text of the given string.
 374      * <p>
 375      * See the {@link #parse(String, ParsePosition)} method for more information
 376      * on date parsing.
 377      *
 378      * @param source A <code>String</code> whose beginning should be parsed.
 379      * @return A <code>Date</code> parsed from the string.
 380      * @exception ParseException if the beginning of the specified string
 381      *            cannot be parsed.
 382      */
 383     public Date parse(String source) throws ParseException
 384     {
 385         ParsePosition pos = new ParsePosition(0);
 386         Date result = parse(source, pos);
 387         if (pos.index == 0)
 388             throw new ParseException("Unparseable date: \"" + source + "\"" ,
 389                 pos.errorIndex);
 390         return result;
 391     }
 392 
 393     /**
 394      * Parse a date/time string according to the given parse position.  For
 395      * example, a time text {@code "07/10/96 4:5 PM, PDT"} will be parsed into a {@code Date}
 396      * that is equivalent to {@code Date(837039900000L)}.
 397      *
 398      * <p> By default, parsing is lenient: If the input is not in the form used
 399      * by this object's format method but can still be parsed as a date, then
 400      * the parse succeeds.  Clients may insist on strict adherence to the
 401      * format by calling {@link #setLenient(boolean) setLenient(false)}.
 402      *
 403      * <p>This parsing operation uses the {@link #calendar} to produce
 404      * a {@code Date}. As a result, the {@code calendar}'s date-time
 405      * fields and the {@code TimeZone} value may have been
 406      * overwritten, depending on subclass implementations. Any {@code
 407      * TimeZone} value that has previously been set by a call to
 408      * {@link #setTimeZone(java.util.TimeZone) setTimeZone} may need
 409      * to be restored for further operations.
 410      *
 411      * @param source  The date/time string to be parsed
 412      *
 413      * @param pos   On input, the position at which to start parsing; on
 414      *              output, the position at which parsing terminated, or the
 415      *              start position if the parse failed.
 416      *
 417      * @return      A {@code Date}, or {@code null} if the input could not be parsed
 418      */
 419     public abstract Date parse(String source, ParsePosition pos);
 420 
 421     /**
 422      * Parses text from a string to produce a <code>Date</code>.
 423      * <p>
 424      * The method attempts to parse text starting at the index given by
 425      * <code>pos</code>.
 426      * If parsing succeeds, then the index of <code>pos</code> is updated
 427      * to the index after the last character used (parsing does not necessarily
 428      * use all characters up to the end of the string), and the parsed
 429      * date is returned. The updated <code>pos</code> can be used to
 430      * indicate the starting point for the next call to this method.
 431      * If an error occurs, then the index of <code>pos</code> is not
 432      * changed, the error index of <code>pos</code> is set to the index of
 433      * the character where the error occurred, and null is returned.
 434      * <p>
 435      * See the {@link #parse(String, ParsePosition)} method for more information
 436      * on date parsing.
 437      *
 438      * @param source A <code>String</code>, part of which should be parsed.
 439      * @param pos A <code>ParsePosition</code> object with index and error
 440      *            index information as described above.
 441      * @return A <code>Date</code> parsed from the string. In case of
 442      *         error, returns null.
 443      * @throws NullPointerException if {@code source} or {@code pos} is null.
 444      */
 445     public Object parseObject(String source, ParsePosition pos) {
 446         return parse(source, pos);
 447     }
 448 
 449     /**
 450      * Constant for full style pattern.
 451      */
 452     public static final int FULL = 0;
 453     /**
 454      * Constant for long style pattern.
 455      */
 456     public static final int LONG = 1;
 457     /**
 458      * Constant for medium style pattern.
 459      */
 460     public static final int MEDIUM = 2;
 461     /**
 462      * Constant for short style pattern.
 463      */
 464     public static final int SHORT = 3;
 465     /**
 466      * Constant for default style pattern.  Its value is MEDIUM.
 467      */
 468     public static final int DEFAULT = MEDIUM;
 469 
 470     /**
 471      * Gets the time formatter with the default formatting style
 472      * for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
 473      * <p>This is equivalent to calling
 474      * {@link #getTimeInstance(int, Locale) getTimeInstance(DEFAULT,
 475      *     Locale.getDefault(Locale.Category.FORMAT))}.
 476      * @see java.util.Locale#getDefault(java.util.Locale.Category)
 477      * @see java.util.Locale.Category#FORMAT
 478      * @return a time formatter.
 479      */
 480     public static final DateFormat getTimeInstance()
 481     {
 482         return get(DEFAULT, 0, 1, Locale.getDefault(Locale.Category.FORMAT));
 483     }
 484 
 485     /**
 486      * Gets the time formatter with the given formatting style
 487      * for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
 488      * <p>This is equivalent to calling
 489      * {@link #getTimeInstance(int, Locale) getTimeInstance(style,
 490      *     Locale.getDefault(Locale.Category.FORMAT))}.
 491      * @see java.util.Locale#getDefault(java.util.Locale.Category)
 492      * @see java.util.Locale.Category#FORMAT
 493      * @param style the given formatting style. For example,
 494      * SHORT for "h:mm a" in the US locale.
 495      * @return a time formatter.
 496      */
 497     public static final DateFormat getTimeInstance(int style)
 498     {
 499         return get(style, 0, 1, Locale.getDefault(Locale.Category.FORMAT));
 500     }
 501 
 502     /**
 503      * Gets the time formatter with the given formatting style
 504      * for the given locale.
 505      * @param style the given formatting style. For example,
 506      * SHORT for "h:mm a" in the US locale.
 507      * @param aLocale the given locale.
 508      * @return a time formatter.
 509      */
 510     public static final DateFormat getTimeInstance(int style,
 511                                                  Locale aLocale)
 512     {
 513         return get(style, 0, 1, aLocale);
 514     }
 515 
 516     /**
 517      * Gets the date formatter with the default formatting style
 518      * for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
 519      * <p>This is equivalent to calling
 520      * {@link #getDateInstance(int, Locale) getDateInstance(DEFAULT,
 521      *     Locale.getDefault(Locale.Category.FORMAT))}.
 522      * @see java.util.Locale#getDefault(java.util.Locale.Category)
 523      * @see java.util.Locale.Category#FORMAT
 524      * @return a date formatter.
 525      */
 526     public static final DateFormat getDateInstance()
 527     {
 528         return get(0, DEFAULT, 2, Locale.getDefault(Locale.Category.FORMAT));
 529     }
 530 
 531     /**
 532      * Gets the date formatter with the given formatting style
 533      * for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
 534      * <p>This is equivalent to calling
 535      * {@link #getDateInstance(int, Locale) getDateInstance(style,
 536      *     Locale.getDefault(Locale.Category.FORMAT))}.
 537      * @see java.util.Locale#getDefault(java.util.Locale.Category)
 538      * @see java.util.Locale.Category#FORMAT
 539      * @param style the given formatting style. For example,
 540      * SHORT for "M/d/yy" in the US locale.
 541      * @return a date formatter.
 542      */
 543     public static final DateFormat getDateInstance(int style)
 544     {
 545         return get(0, style, 2, Locale.getDefault(Locale.Category.FORMAT));
 546     }
 547 
 548     /**
 549      * Gets the date formatter with the given formatting style
 550      * for the given locale.
 551      * @param style the given formatting style. For example,
 552      * SHORT for "M/d/yy" in the US locale.
 553      * @param aLocale the given locale.
 554      * @return a date formatter.
 555      */
 556     public static final DateFormat getDateInstance(int style,
 557                                                  Locale aLocale)
 558     {
 559         return get(0, style, 2, aLocale);
 560     }
 561 
 562     /**
 563      * Gets the date/time formatter with the default formatting style
 564      * for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
 565      * <p>This is equivalent to calling
 566      * {@link #getDateTimeInstance(int, int, Locale) getDateTimeInstance(DEFAULT,
 567      *     DEFAULT, Locale.getDefault(Locale.Category.FORMAT))}.
 568      * @see java.util.Locale#getDefault(java.util.Locale.Category)
 569      * @see java.util.Locale.Category#FORMAT
 570      * @return a date/time formatter.
 571      */
 572     public static final DateFormat getDateTimeInstance()
 573     {
 574         return get(DEFAULT, DEFAULT, 3, Locale.getDefault(Locale.Category.FORMAT));
 575     }
 576 
 577     /**
 578      * Gets the date/time formatter with the given date and time
 579      * formatting styles for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
 580      * <p>This is equivalent to calling
 581      * {@link #getDateTimeInstance(int, int, Locale) getDateTimeInstance(dateStyle,
 582      *     timeStyle, Locale.getDefault(Locale.Category.FORMAT))}.
 583      * @see java.util.Locale#getDefault(java.util.Locale.Category)
 584      * @see java.util.Locale.Category#FORMAT
 585      * @param dateStyle the given date formatting style. For example,
 586      * SHORT for "M/d/yy" in the US locale.
 587      * @param timeStyle the given time formatting style. For example,
 588      * SHORT for "h:mm a" in the US locale.
 589      * @return a date/time formatter.
 590      */
 591     public static final DateFormat getDateTimeInstance(int dateStyle,
 592                                                        int timeStyle)
 593     {
 594         return get(timeStyle, dateStyle, 3, Locale.getDefault(Locale.Category.FORMAT));
 595     }
 596 
 597     /**
 598      * Gets the date/time formatter with the given formatting styles
 599      * for the given locale.
 600      * @param dateStyle the given date formatting style.
 601      * @param timeStyle the given time formatting style.
 602      * @param aLocale the given locale.
 603      * @return a date/time formatter.
 604      */
 605     public static final DateFormat
 606         getDateTimeInstance(int dateStyle, int timeStyle, Locale aLocale)
 607     {
 608         return get(timeStyle, dateStyle, 3, aLocale);
 609     }
 610 
 611     /**
 612      * Get a default date/time formatter that uses the SHORT style for both the
 613      * date and the time.
 614      *
 615      * @return a date/time formatter
 616      */
 617     public static final DateFormat getInstance() {
 618         return getDateTimeInstance(SHORT, SHORT);
 619     }
 620 
 621     /**
 622      * Returns an array of all locales for which the
 623      * <code>get*Instance</code> methods of this class can return
 624      * localized instances.
 625      * The returned array represents the union of locales supported by the Java
 626      * runtime and by installed
 627      * {@link java.text.spi.DateFormatProvider DateFormatProvider} implementations.
 628      * It must contain at least a <code>Locale</code> instance equal to
 629      * {@link java.util.Locale#US Locale.US}.
 630      *
 631      * @return An array of locales for which localized
 632      *         <code>DateFormat</code> instances are available.
 633      */
 634     public static Locale[] getAvailableLocales()
 635     {
 636         LocaleServiceProviderPool pool =
 637             LocaleServiceProviderPool.getPool(DateFormatProvider.class);
 638         return pool.getAvailableLocales();
 639     }
 640 
 641     /**
 642      * Set the calendar to be used by this date format.  Initially, the default
 643      * calendar for the specified or default locale is used.
 644      *
 645      * <p>Any {@link java.util.TimeZone TimeZone} and {@linkplain
 646      * #isLenient() leniency} values that have previously been set are
 647      * overwritten by {@code newCalendar}'s values.
 648      *
 649      * @param newCalendar the new {@code Calendar} to be used by the date format
 650      */
 651     public void setCalendar(Calendar newCalendar)
 652     {
 653         this.calendar = newCalendar;
 654     }
 655 
 656     /**
 657      * Gets the calendar associated with this date/time formatter.
 658      *
 659      * @return the calendar associated with this date/time formatter.
 660      */
 661     public Calendar getCalendar()
 662     {
 663         return calendar;
 664     }
 665 
 666     /**
 667      * Allows you to set the number formatter.
 668      * @param newNumberFormat the given new NumberFormat.
 669      */
 670     public void setNumberFormat(NumberFormat newNumberFormat)
 671     {
 672         this.numberFormat = newNumberFormat;
 673     }
 674 
 675     /**
 676      * Gets the number formatter which this date/time formatter uses to
 677      * format and parse a time.
 678      * @return the number formatter which this date/time formatter uses.
 679      */
 680     public NumberFormat getNumberFormat()
 681     {
 682         return numberFormat;
 683     }
 684 
 685     /**
 686      * Sets the time zone for the calendar of this {@code DateFormat} object.
 687      * This method is equivalent to the following call.
 688      * <blockquote><pre>{@code
 689      * getCalendar().setTimeZone(zone)
 690      * }</pre></blockquote>
 691      *
 692      * <p>The {@code TimeZone} set by this method is overwritten by a
 693      * {@link #setCalendar(java.util.Calendar) setCalendar} call.
 694      *
 695      * <p>The {@code TimeZone} set by this method may be overwritten as
 696      * a result of a call to the parse method.
 697      *
 698      * @param zone the given new time zone.
 699      */
 700     public void setTimeZone(TimeZone zone)
 701     {
 702         calendar.setTimeZone(zone);
 703     }
 704 
 705     /**
 706      * Gets the time zone.
 707      * This method is equivalent to the following call.
 708      * <blockquote><pre>{@code
 709      * getCalendar().getTimeZone()
 710      * }</pre></blockquote>
 711      *
 712      * @return the time zone associated with the calendar of DateFormat.
 713      */
 714     public TimeZone getTimeZone()
 715     {
 716         return calendar.getTimeZone();
 717     }
 718 
 719     /**
 720      * Specify whether or not date/time parsing is to be lenient.  With
 721      * lenient parsing, the parser may use heuristics to interpret inputs that
 722      * do not precisely match this object's format.  With strict parsing,
 723      * inputs must match this object's format.
 724      *
 725      * <p>This method is equivalent to the following call.
 726      * <blockquote><pre>{@code
 727      * getCalendar().setLenient(lenient)
 728      * }</pre></blockquote>
 729      *
 730      * <p>This leniency value is overwritten by a call to {@link
 731      * #setCalendar(java.util.Calendar) setCalendar()}.
 732      *
 733      * @param lenient when {@code true}, parsing is lenient
 734      * @see java.util.Calendar#setLenient(boolean)
 735      */
 736     public void setLenient(boolean lenient)
 737     {
 738         calendar.setLenient(lenient);
 739     }
 740 
 741     /**
 742      * Tell whether date/time parsing is to be lenient.
 743      * This method is equivalent to the following call.
 744      * <blockquote><pre>{@code
 745      * getCalendar().isLenient()
 746      * }</pre></blockquote>
 747      *
 748      * @return {@code true} if the {@link #calendar} is lenient;
 749      *         {@code false} otherwise.
 750      * @see java.util.Calendar#isLenient()
 751      */
 752     public boolean isLenient()
 753     {
 754         return calendar.isLenient();
 755     }
 756 
 757     /**
 758      * Overrides hashCode
 759      */
 760     public int hashCode() {
 761         return numberFormat.hashCode();
 762         // just enough fields for a reasonable distribution
 763     }
 764 
 765     /**
 766      * Overrides equals
 767      */
 768     public boolean equals(Object obj) {
 769         if (this == obj) return true;
 770         if (obj == null || getClass() != obj.getClass()) return false;
 771         DateFormat other = (DateFormat) obj;
 772         return (// calendar.equivalentTo(other.calendar) // THIS API DOESN'T EXIST YET!
 773                 calendar.getFirstDayOfWeek() == other.calendar.getFirstDayOfWeek() &&
 774                 calendar.getMinimalDaysInFirstWeek() == other.calendar.getMinimalDaysInFirstWeek() &&
 775                 calendar.isLenient() == other.calendar.isLenient() &&
 776                 calendar.getTimeZone().equals(other.calendar.getTimeZone()) &&
 777                 numberFormat.equals(other.numberFormat));
 778     }
 779 
 780     /**
 781      * Overrides Cloneable
 782      */
 783     public Object clone()
 784     {
 785         DateFormat other = (DateFormat) super.clone();
 786         other.calendar = (Calendar) calendar.clone();
 787         other.numberFormat = (NumberFormat) numberFormat.clone();
 788         return other;
 789     }
 790 
 791     /**
 792      * Creates a DateFormat with the given time and/or date style in the given
 793      * locale.
 794      * @param timeStyle a value from 0 to 3 indicating the time format,
 795      * ignored if flags is 2
 796      * @param dateStyle a value from 0 to 3 indicating the time format,
 797      * ignored if flags is 1
 798      * @param flags either 1 for a time format, 2 for a date format,
 799      * or 3 for a date/time format
 800      * @param loc the locale for the format
 801      */
 802     private static DateFormat get(int timeStyle, int dateStyle,
 803                                   int flags, Locale loc) {
 804         if ((flags & 1) != 0) {
 805             if (timeStyle < 0 || timeStyle > 3) {
 806                 throw new IllegalArgumentException("Illegal time style " + timeStyle);
 807             }
 808         } else {
 809             timeStyle = -1;
 810         }
 811         if ((flags & 2) != 0) {
 812             if (dateStyle < 0 || dateStyle > 3) {
 813                 throw new IllegalArgumentException("Illegal date style " + dateStyle);
 814             }
 815         } else {
 816             dateStyle = -1;
 817         }
 818 
 819         LocaleProviderAdapter adapter = LocaleProviderAdapter.getAdapter(DateFormatProvider.class, loc);
 820         DateFormat dateFormat = get(adapter, timeStyle, dateStyle, loc);
 821         if (dateFormat == null) {
 822             dateFormat = get(LocaleProviderAdapter.forJRE(), timeStyle, dateStyle, loc);
 823         }
 824         return dateFormat;
 825     }
 826 
 827     private static DateFormat get(LocaleProviderAdapter adapter, int timeStyle, int dateStyle, Locale loc) {
 828         DateFormatProvider provider = adapter.getDateFormatProvider();
 829         DateFormat dateFormat;
 830         if (timeStyle == -1) {
 831             dateFormat = provider.getDateInstance(dateStyle, loc);
 832         } else {
 833             if (dateStyle == -1) {
 834                 dateFormat = provider.getTimeInstance(timeStyle, loc);
 835             } else {
 836                 dateFormat = provider.getDateTimeInstance(dateStyle, timeStyle, loc);
 837             }
 838         }
 839         return dateFormat;
 840     }
 841 
 842     /**
 843      * Create a new date format.
 844      */
 845     protected DateFormat() {}
 846 
 847     /**
 848      * Defines constants that are used as attribute keys in the
 849      * <code>AttributedCharacterIterator</code> returned
 850      * from <code>DateFormat.formatToCharacterIterator</code> and as
 851      * field identifiers in <code>FieldPosition</code>.
 852      * <p>
 853      * The class also provides two methods to map
 854      * between its constants and the corresponding Calendar constants.
 855      *
 856      * @since 1.4
 857      * @see java.util.Calendar
 858      */
 859     public static class Field extends Format.Field {
 860 
 861         // Proclaim serial compatibility with 1.4 FCS
 862         private static final long serialVersionUID = 7441350119349544720L;
 863 
 864         // table of all instances in this class, used by readResolve
 865         private static final Map<String, Field> instanceMap = new HashMap<>(18);
 866         // Maps from Calendar constant (such as Calendar.ERA) to Field
 867         // constant (such as Field.ERA).
 868         private static final Field[] calendarToFieldMapping =
 869                                              new Field[Calendar.FIELD_COUNT];
 870 
 871         /** Calendar field. */
 872         private int calendarField;
 873 
 874         /**
 875          * Returns the <code>Field</code> constant that corresponds to
 876          * the <code>Calendar</code> constant <code>calendarField</code>.
 877          * If there is no direct mapping between the <code>Calendar</code>
 878          * constant and a <code>Field</code>, null is returned.
 879          *
 880          * @throws IllegalArgumentException if <code>calendarField</code> is
 881          *         not the value of a <code>Calendar</code> field constant.
 882          * @param calendarField Calendar field constant
 883          * @return Field instance representing calendarField.
 884          * @see java.util.Calendar
 885          */
 886         public static Field ofCalendarField(int calendarField) {
 887             if (calendarField < 0 || calendarField >=
 888                         calendarToFieldMapping.length) {
 889                 throw new IllegalArgumentException("Unknown Calendar constant "
 890                                                    + calendarField);
 891             }
 892             return calendarToFieldMapping[calendarField];
 893         }
 894 
 895         /**
 896          * Creates a <code>Field</code>.
 897          *
 898          * @param name the name of the <code>Field</code>
 899          * @param calendarField the <code>Calendar</code> constant this
 900          *        <code>Field</code> corresponds to; any value, even one
 901          *        outside the range of legal <code>Calendar</code> values may
 902          *        be used, but <code>-1</code> should be used for values
 903          *        that don't correspond to legal <code>Calendar</code> values
 904          */
 905         protected Field(String name, int calendarField) {
 906             super(name);
 907             this.calendarField = calendarField;
 908             if (this.getClass() == DateFormat.Field.class) {
 909                 instanceMap.put(name, this);
 910                 if (calendarField >= 0) {
 911                     // assert(calendarField < Calendar.FIELD_COUNT);
 912                     calendarToFieldMapping[calendarField] = this;
 913                 }
 914             }
 915         }
 916 
 917         /**
 918          * Returns the <code>Calendar</code> field associated with this
 919          * attribute. For example, if this represents the hours field of
 920          * a <code>Calendar</code>, this would return
 921          * <code>Calendar.HOUR</code>. If there is no corresponding
 922          * <code>Calendar</code> constant, this will return -1.
 923          *
 924          * @return Calendar constant for this field
 925          * @see java.util.Calendar
 926          */
 927         public int getCalendarField() {
 928             return calendarField;
 929         }
 930 
 931         /**
 932          * Resolves instances being deserialized to the predefined constants.
 933          *
 934          * @throws InvalidObjectException if the constant could not be
 935          *         resolved.
 936          * @return resolved DateFormat.Field constant
 937          */
 938         @Override
 939         protected Object readResolve() throws InvalidObjectException {
 940             if (this.getClass() != DateFormat.Field.class) {
 941                 throw new InvalidObjectException("subclass didn't correctly implement readResolve");
 942             }
 943 
 944             Object instance = instanceMap.get(getName());
 945             if (instance != null) {
 946                 return instance;
 947             } else {
 948                 throw new InvalidObjectException("unknown attribute name");
 949             }
 950         }
 951 
 952         //
 953         // The constants
 954         //
 955 
 956         /**
 957          * Constant identifying the era field.
 958          */
 959         public static final Field ERA = new Field("era", Calendar.ERA);
 960 
 961         /**
 962          * Constant identifying the year field.
 963          */
 964         public static final Field YEAR = new Field("year", Calendar.YEAR);
 965 
 966         /**
 967          * Constant identifying the month field.
 968          */
 969         public static final Field MONTH = new Field("month", Calendar.MONTH);
 970 
 971         /**
 972          * Constant identifying the day of month field.
 973          */
 974         public static final Field DAY_OF_MONTH = new
 975                             Field("day of month", Calendar.DAY_OF_MONTH);
 976 
 977         /**
 978          * Constant identifying the hour of day field, where the legal values
 979          * are 1 to 24.
 980          */
 981         public static final Field HOUR_OF_DAY1 = new Field("hour of day 1",-1);
 982 
 983         /**
 984          * Constant identifying the hour of day field, where the legal values
 985          * are 0 to 23.
 986          */
 987         public static final Field HOUR_OF_DAY0 = new
 988                Field("hour of day", Calendar.HOUR_OF_DAY);
 989 
 990         /**
 991          * Constant identifying the minute field.
 992          */
 993         public static final Field MINUTE =new Field("minute", Calendar.MINUTE);
 994 
 995         /**
 996          * Constant identifying the second field.
 997          */
 998         public static final Field SECOND =new Field("second", Calendar.SECOND);
 999 
1000         /**
1001          * Constant identifying the millisecond field.
1002          */
1003         public static final Field MILLISECOND = new
1004                 Field("millisecond", Calendar.MILLISECOND);
1005 
1006         /**
1007          * Constant identifying the day of week field.
1008          */
1009         public static final Field DAY_OF_WEEK = new
1010                 Field("day of week", Calendar.DAY_OF_WEEK);
1011 
1012         /**
1013          * Constant identifying the day of year field.
1014          */
1015         public static final Field DAY_OF_YEAR = new
1016                 Field("day of year", Calendar.DAY_OF_YEAR);
1017 
1018         /**
1019          * Constant identifying the day of week field.
1020          */
1021         public static final Field DAY_OF_WEEK_IN_MONTH =
1022                      new Field("day of week in month",
1023                                             Calendar.DAY_OF_WEEK_IN_MONTH);
1024 
1025         /**
1026          * Constant identifying the week of year field.
1027          */
1028         public static final Field WEEK_OF_YEAR = new
1029               Field("week of year", Calendar.WEEK_OF_YEAR);
1030 
1031         /**
1032          * Constant identifying the week of month field.
1033          */
1034         public static final Field WEEK_OF_MONTH = new
1035             Field("week of month", Calendar.WEEK_OF_MONTH);
1036 
1037         /**
1038          * Constant identifying the time of day indicator
1039          * (e.g. "a.m." or "p.m.") field.
1040          */
1041         public static final Field AM_PM = new
1042                             Field("am pm", Calendar.AM_PM);
1043 
1044         /**
1045          * Constant identifying the hour field, where the legal values are
1046          * 1 to 12.
1047          */
1048         public static final Field HOUR1 = new Field("hour 1", -1);
1049 
1050         /**
1051          * Constant identifying the hour field, where the legal values are
1052          * 0 to 11.
1053          */
1054         public static final Field HOUR0 = new
1055                             Field("hour", Calendar.HOUR);
1056 
1057         /**
1058          * Constant identifying the time zone field.
1059          */
1060         public static final Field TIME_ZONE = new Field("time zone", -1);
1061     }
1062 }