1 /*
2 * Copyright (c) 2000, 2008, 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 * @author IBM Corp.
27 *
28 * Copyright IBM Corp. 1999-2000. All rights reserved.
29 */
30
31 package javax.management;
32
33 import java.io.Serializable;
34
35 // Javadoc imports:
36 import java.lang.management.MemoryUsage;
37 import java.util.Arrays;
38 import java.util.Locale;
39 import java.util.ResourceBundle;
40 import javax.management.openmbean.CompositeData;
41 import javax.management.openmbean.OpenMBeanAttributeInfoSupport;
42 import javax.management.openmbean.OpenMBeanOperationInfoSupport;
43 import javax.management.openmbean.OpenMBeanParameterInfoSupport;
44 import javax.management.openmbean.OpenType;
45
46 /**
47 * <p>Additional metadata for a JMX element. A {@code Descriptor}
48 * is associated with a {@link MBeanInfo}, {@link MBeanAttributeInfo}, etc.
49 * It consists of a collection of fields. A field is a name and an
50 * associated value.</p>
51 *
52 * <p>Field names are not case-sensitive. The names {@code descriptorType},
53 * {@code descriptortype}, and {@code DESCRIPTORTYPE} are all equivalent.
54 * However, the case that was used when the field was first set is preserved
55 * in the result of the {@link #getFields} and {@link #getFieldNames}
56 * methods.</p>
57 *
58 * <p>Not all field names and values are predefined.
59 * New fields can be defined and added by any program.</p>
60 *
61 * <p>A descriptor can be mutable or immutable.
62 * An immutable descriptor, once created, never changes.
63 * The <code>Descriptor</code> methods that could modify the contents
64 * of the descriptor will throw an exception
65 * for an immutable descriptor. Immutable descriptors are usually
66 * instances of {@link ImmutableDescriptor} or a subclass. Mutable
67 * descriptors are usually instances of
68 * {@link javax.management.modelmbean.DescriptorSupport} or a subclass.
69 *
70 * <p>Certain fields are used by the JMX implementation. This means
71 * either that the presence of the field may change the behavior of
72 * the JMX API or that the field may be set in descriptors returned by
73 * the JMX API. These fields appear in <i>italics</i> in the table
74 * below, and each one has a corresponding constant in the {@link JMX}
75 * class. For example, the field {@code defaultValue} is represented
76 * by the constant {@link JMX#DEFAULT_VALUE_FIELD}.</p>
77 *
78 * <p>Certain other fields have conventional meanings described in the
79 * table below but they are not required to be understood or set by
80 * the JMX implementation.</p>
81 *
82 * <p>Field names defined by the JMX specification in this and all
83 * future versions will never contain a period (.). Users can safely
84 * create their own fields by including a period in the name and be
85 * sure that these names will not collide with any future version of
86 * the JMX API. It is recommended to follow the Java package naming
87 * convention to avoid collisions between field names from different
88 * origins. For example, a field created by {@code example.com} might
89 * have the name {@code com.example.interestLevel}.</p>
90 *
91 * <p>Note that the values in the {@code defaultValue}, {@code
92 * legalValues}, {@code maxValue}, and {@code minValue} fields should
93 * be consistent with the type returned by the {@code getType()}
94 * method for the associated {@code MBeanAttributeInfo} or {@code
95 * MBeanParameterInfo}. For MXBeans, this means that they should be
96 * of the mapped Java type, called <em>opendata</em>(J) in the <a
97 * href="MXBean.html#mapping-rules">MXBean type mapping rules</a>.</p>
98 *
99 * <table border="1" cellpadding="5">
100 *
101 * <tr><th>Name</th><th>Type</th><th>Used in</th><th>Meaning</th></tr>
102 *
103 * <tr id="defaultValue"><td><i>defaultValue</i><td>Object</td>
104 * <td>MBeanAttributeInfo<br>MBeanParameterInfo</td>
105 *
106 * <td>Default value for an attribute or parameter. See
107 * {@link javax.management.openmbean}.</td>
108 *
109 * <tr><td>deprecated</td><td>String</td><td>Any</td>
110 *
111 * <td>An indication that this element of the information model is no
112 * longer recommended for use. A set of MBeans defined by an
113 * application is collectively called an <em>information model</em>.
114 * The convention is for the value of this field to contain a string
115 * that is the version of the model in which the element was first
116 * deprecated, followed by a space, followed by an explanation of the
117 * deprecation, for example {@code "1.3 Replaced by the Capacity
118 * attribute"}.</td>
119 *
120 * <tr><td id="descriptionResourceBundleBaseName">descriptionResource<br>
121 * BundleBaseName</td><td>String</td><td>Any</td>
122 *
123 * <td>The base name for the {@link ResourceBundle} in which the key given in
124 * the {@code descriptionResourceKey} field can be found, for example
125 * {@code "com.example.myapp.MBeanResources"}. The meaning of this
126 * field is defined by this specification but the field is not set or
127 * used by the JMX API itself.</td>
128 *
129 * <tr><td id="descriptionResourceKey">descriptionResourceKey</td>
130 * <td>String</td><td>Any</td>
131 *
132 * <td>A resource key for the description of this element. In
133 * conjunction with the {@code descriptionResourceBundleBaseName},
134 * this can be used to find a localized version of the description.
135 * The meaning of this field is defined by this specification but the
136 * field is not set or used by the JMX API itself.</td>
137 *
138 * <tr><td>enabled</td><td>String</td>
139 * <td>MBeanAttributeInfo<br>MBeanNotificationInfo<br>MBeanOperationInfo</td>
140 *
141 * <td>The string {@code "true"} or {@code "false"} according as this
142 * item is enabled. When an attribute or operation is not enabled, it
143 * exists but cannot currently be accessed. A user interface might
144 * present it as a greyed-out item. For example, an attribute might
145 * only be meaningful after the {@code start()} method of an MBean has
146 * been called, and is otherwise disabled. Likewise, a notification
147 * might be disabled if it cannot currently be emitted but could be in
148 * other circumstances.</td>
149 *
150 * <tr id="exceptions"><td>exceptions<td>String[]</td>
151 * <td>MBeanAttributeInfo, MBeanConstructorInfo, MBeanOperationInfo</td>
152 *
153 * <td>The class names of the exceptions that can be thrown when invoking a
154 * constructor or operation, or getting an attribute. The meaning of this field
155 * is defined by this specification but the field is not set or used by the
156 * JMX API itself. Exceptions thrown when
157 * setting an attribute are specified by the field
158 * <a href="#setExceptions">{@code setExceptions}</a>.
159 *
160 * <tr id="immutableInfo"><td><i>immutableInfo</i><td>String</td>
161 * <td>MBeanInfo</td>
162 *
163 * <td>The string {@code "true"} or {@code "false"} according as this
164 * MBean's MBeanInfo is <em>immutable</em>. When this field is true,
165 * the MBeanInfo for the given MBean is guaranteed not to change over
166 * the lifetime of the MBean. Hence, a client can read it once and
167 * cache the read value. When this field is false or absent, there is
168 * no such guarantee, although that does not mean that the MBeanInfo
169 * will necessarily change. See also the <a
170 * href="MBeanInfo.html#info-changed">{@code "jmx.mbean.info.changed"}</a>
171 * notification.</td>
172 *
173 * <tr id="infoTimeout"><td>infoTimeout</td><td>String<br>Long</td><td>MBeanInfo</td>
174 *
175 * <td>The time in milli-seconds that the MBeanInfo can reasonably be
176 * expected to be unchanged. The value can be a {@code Long} or a
177 * decimal string. This provides a hint from a DynamicMBean or any
178 * MBean that does not define {@code immutableInfo} as {@code true}
179 * that the MBeanInfo is not likely to change within this period and
180 * therefore can be cached. When this field is missing or has the
181 * value zero, it is not recommended to cache the MBeanInfo unless it
182 * has the {@code immutableInfo} set to {@code true} or it has <a
183 * href="MBeanInfo.html#info-changed">{@code "jmx.mbean.info.changed"}</a> in
184 * its {@link MBeanNotificationInfo} array.</td></tr>
185 *
186 * <tr id="interfaceClassName"><td><i>interfaceClassName</i></td>
187 * <td>String</td><td>MBeanInfo</td>
188 *
189 * <td>The Java interface name for a Standard MBean or MXBean, as
190 * returned by {@link Class#getName()}. A Standard MBean or MXBean
191 * registered directly in the MBean Server or created using the {@link
192 * StandardMBean} class will have this field in its MBeanInfo
193 * Descriptor.</td>
194 *
195 * <tr id="legalValues"><td><i>legalValues</i></td>
196 * <td>{@literal Set<?>}</td><td>MBeanAttributeInfo<br>MBeanParameterInfo</td>
197 *
198 * <td>Legal values for an attribute or parameter. See
199 * {@link javax.management.openmbean}.</td>
200 *
201 * <tr id="locale"><td>locale</td>
202 * <td>String</td><td>Any</td>
203 *
204 * <td>The {@linkplain Locale locale} of the description in this
205 * {@code MBeanInfo}, {@code MBeanAttributeInfo}, etc, as returned
206 * by {@link Locale#toString()}.</td>
207 *
208 * <tr id="maxValue"><td><i>maxValue</i><td>Object</td>
209 * <td>MBeanAttributeInfo<br>MBeanParameterInfo</td>
210 *
211 * <td>Maximum legal value for an attribute or parameter. See
212 * {@link javax.management.openmbean}.</td>
213 *
214 * <tr id="metricType"><td>metricType</td><td>String</td>
215 * <td>MBeanAttributeInfo<br>MBeanOperationInfo</td>
216 *
217 * <td>The type of a metric, one of the strings "counter" or "gauge".
218 * A metric is a measurement exported by an MBean, usually an
219 * attribute but sometimes the result of an operation. A metric that
220 * is a <em>counter</em> has a value that never decreases except by
221 * being reset to a starting value. Counter metrics are almost always
222 * non-negative integers. An example might be the number of requests
223 * received. A metric that is a <em>gauge</em> has a numeric value
224 * that can increase or decrease. Examples might be the number of
225 * open connections or a cache hit rate or a temperature reading.
226 *
227 * <tr id="minValue"><td><i>minValue</i><td>Object</td>
228 * <td>MBeanAttributeInfo<br>MBeanParameterInfo</td>
229 *
230 * <td>Minimum legal value for an attribute or parameter. See
231 * {@link javax.management.openmbean}.</td>
232 *
233 * <tr id="mxbean"><td><i>mxbean</i><td>String</td>
234 * <td>MBeanInfo</td>
235 *
236 * <td>The string {@code "true"} or {@code "false"} according as this
237 * MBean is an {@link MXBean}. A Standard MBean or MXBean registered
238 * directly with the MBean Server or created using the {@link
239 * StandardMBean} class will have this field in its MBeanInfo
240 * Descriptor.</td>
241 *
242 * <tr id="openType"><td><i>openType</i><td>{@link OpenType}</td>
243 * <td>MBeanAttributeInfo<br>MBeanOperationInfo<br>MBeanParameterInfo</td>
244 *
245 * <td><p>The Open Type of this element. In the case of {@code
246 * MBeanAttributeInfo} and {@code MBeanParameterInfo}, this is the
247 * Open Type of the attribute or parameter. In the case of {@code
248 * MBeanOperationInfo}, it is the Open Type of the return value. This
249 * field is set in the Descriptor for all instances of {@link
250 * OpenMBeanAttributeInfoSupport}, {@link
251 * OpenMBeanOperationInfoSupport}, and {@link
252 * OpenMBeanParameterInfoSupport}. It is also set for attributes,
253 * operations, and parameters of MXBeans.</p>
254 *
255 * <p>This field can be set for an {@code MBeanNotificationInfo}, in
256 * which case it indicates the Open Type that the {@link
257 * Notification#getUserData() user data} will have.</td>
258 *
259 * <tr id="originalType"><td><i>originalType</i><td>String</td>
260 * <td>MBeanAttributeInfo<br>MBeanOperationInfo<br>MBeanParameterInfo</td>
261 *
262 * <td><p>The original Java type of this element as it appeared in the
263 * {@link MXBean} interface method that produced this {@code
264 * MBeanAttributeInfo} (etc). For example, a method<br> <code>public
265 * </code> {@link MemoryUsage}<code> getHeapMemoryUsage();</code><br>
266 * in an MXBean interface defines an attribute called {@code
267 * HeapMemoryUsage} of type {@link CompositeData}. The {@code
268 * originalType} field in the Descriptor for this attribute will have
269 * the value {@code "java.lang.management.MemoryUsage"}.
270 *
271 * <p>The format of this string is described in the section <a
272 * href="MXBean.html#type-names">Type Names</a> of the MXBean
273 * specification.</p>
274 *
275 * <tr id="setExceptions"><td><i>setExceptions</i><td>String[]</td>
276 * <td>MBeanAttributeInfo</td>
277 *
278 * <td>The class names of the exceptions that can be thrown when setting
279 * an attribute. The meaning of this field
280 * is defined by this specification but the field is not set or used by the
281 * JMX API itself. Exceptions thrown when getting an attribute are specified
282 * by the field <a href="#exceptions">{@code exceptions}</a>.
283 *
284 * <tr><td>severity</td><td>String<br>Integer</td>
285 * <td>MBeanNotificationInfo</td>
286 *
287 * <td>The severity of this notification. It can be 0 to mean
288 * unknown severity or a value from 1 to 6 representing decreasing
289 * levels of severity. It can be represented as a decimal string or
290 * an {@code Integer}.</td>
291 *
292 * <tr><td>since</td><td>String</td><td>Any</td>
293 *
294 * <td>The version of the information model in which this element
295 * was introduced. A set of MBeans defined by an application is
296 * collectively called an <em>information model</em>. The
297 * application may also define versions of this model, and use the
298 * {@code "since"} field to record the version in which an element
299 * first appeared.</td>
300 *
301 * <tr><td>units</td><td>String</td>
302 * <td>MBeanAttributeInfo<br>MBeanParameterInfo<br>MBeanOperationInfo</td>
303 *
304 * <td>The units in which an attribute, parameter, or operation return
305 * value is measured, for example {@code "bytes"} or {@code
306 * "seconds"}.</td>
307 *
308 * </table>
309 *
310 * <p>Some additional fields are defined by Model MBeans. See the
311 * information for <a href="modelmbean/ModelMBeanInfo.html#descriptor"><!--
312 * -->{@code ModelMBeanInfo}</a>,
313 * <a href="modelmbean/ModelMBeanAttributeInfo.html#descriptor"><!--
314 * -->{@code ModelMBeanAttributeInfo}</a>,
315 * <a href="modelmbean/ModelMBeanConstructorInfo.html#descriptor"><!--
316 * -->{@code ModelMBeanConstructorInfo}</a>,
317 * <a href="modelmbean/ModelMBeanNotificationInfo.html#descriptor"><!--
318 * -->{@code ModelMBeanNotificationInfo}</a>, and
319 * <a href="modelmbean/ModelMBeanOperationInfo.html#descriptor"><!--
320 * -->{@code ModelMBeanOperationInfo}</a>, as
321 * well as the chapter "Model MBeans" of the <a
322 * href="http://java.sun.com/products/JavaManagement/download.html">JMX
323 * Specification</a>. The following table summarizes these fields. Note
324 * that when the Type in this table is Number, a String that is the decimal
325 * representation of a Long can also be used.</p>
326 *
327 * <p>Nothing prevents the use of these fields in MBeans that are not Model
328 * MBeans. The <a href="#displayName">displayName</a>, <a href="#severity"><!--
329 * -->severity</a>, and <a href="#visibility">visibility</a> fields are of
330 * interest outside Model MBeans, for example. But only Model MBeans have
331 * a predefined behavior for these fields.</p>
332 *
333 * <table border="1" cellpadding="5">
334 *
335 * <tr><th>Name</th><th>Type</th><th>Used in</th><th>Meaning</th></tr>
336 *
337 * <tr><td>class</td><td>String</td><td>ModelMBeanOperationInfo</td>
338 * <td>Class where method is defined (fully qualified).</td></tr>
339 *
340 * <tr><td>currencyTimeLimit</td><td>Number</td>
341 * <td>ModelMBeanInfo<br>ModelMBeanAttributeInfo<br>ModelMBeanOperationInfo</td>
342 * <td>How long cached value is valid: <0 never, =0 always,
343 * >0 seconds.</td></tr>
344 *
345 * <tr><td>default</td><td>Object</td><td>ModelMBeanAttributeInfo</td>
346 * <td>Default value for attribute.</td></tr>
347 *
348 * <tr><td>descriptorType</td><td>String</td><td>Any</td>
349 * <td>Type of descriptor, "mbean", "attribute", "constructor", "operation",
350 * or "notification".</td></tr>
351 *
352 * <tr id="displayName"><td>displayName</td><td>String</td><td>Any</td>
353 * <td>Human readable name of this item.</td></tr>
354 *
355 * <tr><td>export</td><td>String</td><td>ModelMBeanInfo</td>
356 * <td>Name to be used to export/expose this MBean so that it is
357 * findable by other JMX Agents.</td></tr>
358 *
359 * <tr><td>getMethod</td><td>String</td><td>ModelMBeanAttributeInfo</td>
360 * <td>Name of operation descriptor for get method.</td></tr>
361 *
362 * <tr><td>lastUpdatedTimeStamp</td><td>Number</td>
363 * <td>ModelMBeanAttributeInfo<br>ModelMBeanOperationInfo</td>
364 * <td>When <a href="#value-field">value</a> was set.</td></tr>
365 *
366 * <tr><td>log</td><td>String</td><td>ModelMBeanInfo<br>ModelMBeanNotificationInfo</td>
367 * <td>t or T: log all notifications, f or F: log no notifications.</td></tr>
368 *
369 * <tr><td>logFile</td><td>String</td><td>ModelMBeanInfo<br>ModelMBeanNotificationInfo</td>
370 * <td>Fully qualified filename to log events to.</td></tr>
371 *
372 * <tr><td>messageID</td><td>String</td><td>ModelMBeanNotificationInfo</td>
373 * <td>Unique key for message text (to allow translation, analysis).</td></tr>
374 *
375 * <tr><td>messageText</td><td>String</td><td>ModelMBeanNotificationInfo</td>
376 * <td>Text of notification.</td></tr>
377 *
378 * <tr><td>name</td><td>String</td><td>Any</td>
379 * <td>Name of this item.</td></tr>
380 *
381 * <tr><td>persistFile</td><td>String</td><td>ModelMBeanInfo</td>
382 * <td>File name into which the MBean should be persisted.</td></tr>
383 *
384 * <tr><td>persistLocation</td><td>String</td><td>ModelMBeanInfo</td>
385 * <td>The fully qualified directory name where the MBean should be
386 * persisted (if appropriate).</td></tr>
387 *
388 * <tr><td>persistPeriod</td><td>Number</td>
389 * <td>ModelMBeanInfo<br>ModelMBeanAttributeInfo</td>
390 * <td>Frequency of persist cycle in seconds. Used when persistPolicy is
391 * "OnTimer" or "NoMoreOftenThan".</td></tr>
392 *
393 * <tr><td>persistPolicy</td><td>String</td>
394 * <td>ModelMBeanInfo<br>ModelMBeanAttributeInfo</td>
395 * <td>One of: OnUpdate|OnTimer|NoMoreOftenThan|OnUnregister|Always|Never.
396 * See the section "MBean Descriptor Fields" in the JMX specification
397 * document.</td></tr>
398 *
399 * <tr><td>presentationString</td><td>String</td><td>Any</td>
400 * <td>XML formatted string to allow presentation of data.</td></tr>
401 *
402 * <tr><td>protocolMap</td><td>Descriptor</td><td>ModelMBeanAttributeInfo</td>
403 * <td>See the section "Protocol Map Support" in the JMX specification
404 * document. Mappings must be appropriate for the attribute and entries
405 * can be updated or augmented at runtime.</td></tr>
406 *
407 * <tr><td>role</td><td>String</td>
408 * <td>ModelMBeanConstructorInfo<br>ModelMBeanOperationInfo</td>
409 * <td>One of "constructor", "operation", "getter", or "setter".</td></tr>
410 *
411 * <tr><td>setMethod</td><td>String</td><td>ModelMBeanAttributeInfo</td>
412 * <td>Name of operation descriptor for set method.</td></tr>
413 *
414 * <tr id="severity"><td>severity</td><td>Number</td>
415 * <td>ModelMBeanNotificationInfo</td>
416 * <td>0-6 where 0: unknown; 1: non-recoverable;
417 * 2: critical, failure; 3: major, severe;
418 * 4: minor, marginal, error; 5: warning;
419 * 6: normal, cleared, informative</td></tr>
420 *
421 * <tr><td>targetObject</td><td>Object</td><td>ModelMBeanOperationInfo</td>
422 * <td>Object on which to execute this method.</td></tr>
423 *
424 * <tr><td>targetType</td><td>String</td><td>ModelMBeanOperationInfo</td>
425 * <td>type of object reference for targetObject. Can be:
426 * ObjectReference | Handle | EJBHandle | IOR | RMIReference.</td></tr>
427 *
428 * <tr id="value-field"><td>value</td><td>Object</td>
429 * <td>ModelMBeanAttributeInfo<br>ModelMBeanOperationInfo</td>
430 * <td>Current (cached) value for attribute or operation.</td></tr>
431 *
432 * <tr id="visibility"><td>visibility</td><td>Number</td><td>Any</td>
433 * <td>1-4 where 1: always visible, 4: rarely visible.</td></tr>
434 *
435 * </table>
436 *
437 * @since 1.5
438 */
439 public interface Descriptor extends Serializable, Cloneable
440 {
441
442 /**
443 * Returns the value for a specific field name, or null if no value
444 * is present for that name.
445 *
446 * @param fieldName the field name.
447 *
448 * @return the corresponding value, or null if the field is not present.
449 *
450 * @exception RuntimeOperationsException if the field name is illegal.
451 */
452 public Object getFieldValue(String fieldName)
453 throws RuntimeOperationsException;
454
455 /**
456 * <p>Sets the value for a specific field name. This will
457 * modify an existing field or add a new field.</p>
458 *
459 * <p>The field value will be validated before it is set.
460 * If it is not valid, then an exception will be thrown.
461 * The meaning of validity is dependent on the descriptor
462 * implementation.</p>
463 *
464 * @param fieldName The field name to be set. Cannot be null or empty.
465 * @param fieldValue The field value to be set for the field
466 * name. Can be null if that is a valid value for the field.
467 *
468 * @exception RuntimeOperationsException if the field name or field value
469 * is illegal (wrapped exception is {@link IllegalArgumentException}); or
470 * if the descriptor is immutable (wrapped exception is
471 * {@link UnsupportedOperationException}).
472 */
473 public void setField(String fieldName, Object fieldValue)
474 throws RuntimeOperationsException;
475
476
477 /**
478 * Returns all of the fields contained in this descriptor as a string array.
479 *
480 * @return String array of fields in the format <i>fieldName=fieldValue</i>
481 * <br>If the value of a field is not a String, then the toString() method
482 * will be called on it and the returned value, enclosed in parentheses,
483 * used as the value for the field in the returned array. If the value
484 * of a field is null, then the value of the field in the returned array
485 * will be empty. If the descriptor is empty, you will get
486 * an empty array.
487 *
488 * @see #setFields
489 */
490 public String[] getFields();
491
492
493 /**
494 * Returns all the field names in the descriptor.
495 *
496 * @return String array of field names. If the descriptor is empty,
497 * you will get an empty array.
498 */
499 public String[] getFieldNames();
500
501 /**
502 * Returns all the field values in the descriptor as an array of Objects. The
503 * returned values are in the same order as the {@code fieldNames} String array parameter.
504 *
505 * @param fieldNames String array of the names of the fields that
506 * the values should be returned for. If the array is empty then
507 * an empty array will be returned. If the array is null then all
508 * values will be returned, as if the parameter were the array
509 * returned by {@link #getFieldNames()}. If a field name in the
510 * array does not exist, including the case where it is null or
511 * the empty string, then null is returned for the matching array
512 * element being returned.
513 *
514 * @return Object array of field values. If the list of {@code fieldNames}
515 * is empty, you will get an empty array.
516 */
517 public Object[] getFieldValues(String... fieldNames);
518
519 /**
520 * Removes a field from the descriptor.
521 *
522 * @param fieldName String name of the field to be removed.
523 * If the field name is illegal or the field is not found,
524 * no exception is thrown.
525 *
526 * @exception RuntimeOperationsException if a field of the given name
527 * exists and the descriptor is immutable. The wrapped exception will
528 * be an {@link UnsupportedOperationException}.
529 */
530 public void removeField(String fieldName);
531
532 /**
533 * <p>Sets all fields in the field names array to the new value with
534 * the same index in the field values array. Array sizes must match.</p>
535 *
536 * <p>The field value will be validated before it is set.
537 * If it is not valid, then an exception will be thrown.
538 * If the arrays are empty, then no change will take effect.</p>
539 *
540 * @param fieldNames String array of field names. The array and array
541 * elements cannot be null.
542 * @param fieldValues Object array of the corresponding field values.
543 * The array cannot be null. Elements of the array can be null.
544 *
545 * @throws RuntimeOperationsException if the change fails for any reason.
546 * Wrapped exception is {@link IllegalArgumentException} if
547 * {@code fieldNames} or {@code fieldValues} is null, or if
548 * the arrays are of different lengths, or if there is an
549 * illegal value in one of them.
550 * Wrapped exception is {@link UnsupportedOperationException}
551 * if the descriptor is immutable, and the call would change
552 * its contents.
553 *
554 * @see #getFields
555 */
556 public void setFields(String[] fieldNames, Object[] fieldValues)
557 throws RuntimeOperationsException;
558
559
560 /**
561 * <p>Returns a descriptor which is equal to this descriptor.
562 * Changes to the returned descriptor will have no effect on this
563 * descriptor, and vice versa. If this descriptor is immutable,
564 * it may fulfill this condition by returning itself.</p>
565 * @exception RuntimeOperationsException for illegal value for field names
566 * or field values.
567 * If the descriptor construction fails for any reason, this exception will
568 * be thrown.
569 * @return A descriptor which is equal to this descriptor.
570 */
571 public Object clone() throws RuntimeOperationsException;
572
573
574 /**
575 * Returns true if all of the fields have legal values given their
576 * names.
577 *
578 * @return true if the values are legal.
579 *
580 * @exception RuntimeOperationsException If the validity checking fails for
581 * any reason, this exception will be thrown.
582 * The method returns false if the descriptor is not valid, but throws
583 * this exception if the attempt to determine validity fails.
584 */
585 public boolean isValid() throws RuntimeOperationsException;
586
587 /**
588 * <p>Compares this descriptor to the given object. The objects are equal if
589 * the given object is also a Descriptor, and if the two Descriptors have
590 * the same field names (possibly differing in case) and the same
591 * associated values. The respective values for a field in the two
592 * Descriptors are equal if the following conditions hold:</p>
593 *
594 * <ul>
595 * <li>If one value is null then the other must be too.</li>
596 * <li>If one value is a primitive array then the other must be a primitive
597 * array of the same type with the same elements.</li>
598 * <li>If one value is an object array then the other must be too and
599 * {@link Arrays#deepEquals(Object[],Object[])} must return true.</li>
600 * <li>Otherwise {@link Object#equals(Object)} must return true.</li>
601 * </ul>
602 *
603 * @param obj the object to compare with.
604 *
605 * @return {@code true} if the objects are the same; {@code false}
606 * otherwise.
607 *
608 * @since 1.6
609 */
610 public boolean equals(Object obj);
611
612 /**
613 * <p>Returns the hash code value for this descriptor. The hash
614 * code is computed as the sum of the hash codes for each field in
615 * the descriptor. The hash code of a field with name {@code n}
616 * and value {@code v} is {@code n.toLowerCase().hashCode() ^ h}.
617 * Here {@code h} is the hash code of {@code v}, computed as
618 * follows:</p>
619 *
620 * <ul>
621 * <li>If {@code v} is null then {@code h} is 0.</li>
622 * <li>If {@code v} is a primitive array then {@code h} is computed using
623 * the appropriate overloading of {@code java.util.Arrays.hashCode}.</li>
624 * <li>If {@code v} is an object array then {@code h} is computed using
625 * {@link Arrays#deepHashCode(Object[])}.</li>
626 * <li>Otherwise {@code h} is {@code v.hashCode()}.</li>
627 * </ul>
628 *
629 * @return A hash code value for this object.
630 *
631 * @since 1.6
632 */
633 public int hashCode();
634 }