1 /*
2 * Copyright (c) 2012, 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
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24 */
25
26 /*
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file:
31 *
32 * Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
33 *
34 * All rights reserved.
35 *
36 * Redistribution and use in source and binary forms, with or without
37 * modification, are permitted provided that the following conditions are met:
38 *
39 * * Redistributions of source code must retain the above copyright notice,
40 * this list of conditions and the following disclaimer.
41 *
42 * * Redistributions in binary form must reproduce the above copyright notice,
43 * this list of conditions and the following disclaimer in the documentation
44 * and/or other materials provided with the distribution.
45 *
46 * * Neither the name of JSR-310 nor the names of its contributors
47 * may be used to endorse or promote products derived from this software
48 * without specific prior written permission.
49 *
50 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
51 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
52 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
53 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
54 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
55 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
56 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
57 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
58 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
59 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
60 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
61 */
62 package java.time;
63
64 import java.io.DataOutput;
65 import java.io.IOException;
66 import java.io.InvalidObjectException;
67 import java.io.ObjectInputStream;
68 import java.io.Serializable;
69 import java.time.format.DateTimeFormatterBuilder;
70 import java.time.format.TextStyle;
71 import java.time.temporal.TemporalAccessor;
72 import java.time.temporal.TemporalField;
73 import java.time.temporal.TemporalQueries;
74 import java.time.temporal.TemporalQuery;
75 import java.time.temporal.UnsupportedTemporalTypeException;
76 import java.time.zone.ZoneRules;
77 import java.time.zone.ZoneRulesException;
78 import java.time.zone.ZoneRulesProvider;
79 import java.util.HashSet;
80 import java.util.Locale;
81 import java.util.Map;
82 import java.util.Objects;
83 import java.util.Set;
84 import java.util.TimeZone;
85
86 import static java.util.Map.entry;
87
88 /**
89 * A time-zone ID, such as {@code Europe/Paris}.
90 * <p>
91 * A {@code ZoneId} is used to identify the rules used to convert between
92 * an {@link Instant} and a {@link LocalDateTime}.
93 * There are two distinct types of ID:
94 * <ul>
95 * <li>Fixed offsets - a fully resolved offset from UTC/Greenwich, that uses
96 * the same offset for all local date-times
97 * <li>Geographical regions - an area where a specific set of rules for finding
98 * the offset from UTC/Greenwich apply
99 * </ul>
100 * Most fixed offsets are represented by {@link ZoneOffset}.
101 * Calling {@link #normalized()} on any {@code ZoneId} will ensure that a
102 * fixed offset ID will be represented as a {@code ZoneOffset}.
103 * <p>
104 * The actual rules, describing when and how the offset changes, are defined by {@link ZoneRules}.
105 * This class is simply an ID used to obtain the underlying rules.
106 * This approach is taken because rules are defined by governments and change
107 * frequently, whereas the ID is stable.
108 * <p>
109 * The distinction has other effects. Serializing the {@code ZoneId} will only send
110 * the ID, whereas serializing the rules sends the entire data set.
111 * Similarly, a comparison of two IDs only examines the ID, whereas
112 * a comparison of two rules examines the entire data set.
113 *
114 * <h3>Time-zone IDs</h3>
115 * The ID is unique within the system.
116 * There are three types of ID.
117 * <p>
118 * The simplest type of ID is that from {@code ZoneOffset}.
119 * This consists of 'Z' and IDs starting with '+' or '-'.
120 * <p>
121 * The next type of ID are offset-style IDs with some form of prefix,
122 * such as 'GMT+2' or 'UTC+01:00'.
123 * The recognised prefixes are 'UTC', 'GMT' and 'UT'.
124 * The offset is the suffix and will be normalized during creation.
125 * These IDs can be normalized to a {@code ZoneOffset} using {@code normalized()}.
126 * <p>
127 * The third type of ID are region-based IDs. A region-based ID must be of
128 * two or more characters, and not start with 'UTC', 'GMT', 'UT' '+' or '-'.
129 * Region-based IDs are defined by configuration, see {@link ZoneRulesProvider}.
130 * The configuration focuses on providing the lookup from the ID to the
131 * underlying {@code ZoneRules}.
132 * <p>
133 * Time-zone rules are defined by governments and change frequently.
134 * There are a number of organizations, known here as groups, that monitor
135 * time-zone changes and collate them.
136 * The default group is the IANA Time Zone Database (TZDB).
137 * Other organizations include IATA (the airline industry body) and Microsoft.
138 * <p>
139 * Each group defines its own format for the region ID it provides.
140 * The TZDB group defines IDs such as 'Europe/London' or 'America/New_York'.
141 * TZDB IDs take precedence over other groups.
142 * <p>
143 * It is strongly recommended that the group name is included in all IDs supplied by
144 * groups other than TZDB to avoid conflicts. For example, IATA airline time-zone
145 * region IDs are typically the same as the three letter airport code.
146 * However, the airport of Utrecht has the code 'UTC', which is obviously a conflict.
147 * The recommended format for region IDs from groups other than TZDB is 'group~region'.
148 * Thus if IATA data were defined, Utrecht airport would be 'IATA~UTC'.
149 *
150 * <h3>Serialization</h3>
151 * This class can be serialized and stores the string zone ID in the external form.
152 * The {@code ZoneOffset} subclass uses a dedicated format that only stores the
153 * offset from UTC/Greenwich.
154 * <p>
155 * A {@code ZoneId} can be deserialized in a Java Runtime where the ID is unknown.
156 * For example, if a server-side Java Runtime has been updated with a new zone ID, but
157 * the client-side Java Runtime has not been updated. In this case, the {@code ZoneId}
158 * object will exist, and can be queried using {@code getId}, {@code equals},
159 * {@code hashCode}, {@code toString}, {@code getDisplayName} and {@code normalized}.
160 * However, any call to {@code getRules} will fail with {@code ZoneRulesException}.
161 * This approach is designed to allow a {@link ZonedDateTime} to be loaded and
162 * queried, but not modified, on a Java Runtime with incomplete time-zone information.
163 *
164 * <p>
165 * This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
166 * class; use of identity-sensitive operations (including reference equality
167 * ({@code ==}), identity hash code, or synchronization) on instances of
168 * {@code ZoneId} may have unpredictable results and should be avoided.
169 * The {@code equals} method should be used for comparisons.
170 *
171 * @implSpec
172 * This abstract class has two implementations, both of which are immutable and thread-safe.
173 * One implementation models region-based IDs, the other is {@code ZoneOffset} modelling
174 * offset-based IDs. This difference is visible in serialization.
175 *
176 * @since 1.8
177 */
178 public abstract class ZoneId implements Serializable {
179
180 /**
181 * A map of zone overrides to enable the short time-zone names to be used.
182 * <p>
183 * Use of short zone IDs has been deprecated in {@code java.util.TimeZone}.
184 * This map allows the IDs to continue to be used via the
185 * {@link #of(String, Map)} factory method.
186 * <p>
187 * This map contains a mapping of the IDs that is in line with TZDB 2005r and
188 * later, where 'EST', 'MST' and 'HST' map to IDs which do not include daylight
189 * savings.
190 * <p>
191 * This maps as follows:
192 * <ul>
193 * <li>EST - -05:00</li>
194 * <li>HST - -10:00</li>
195 * <li>MST - -07:00</li>
196 * <li>ACT - Australia/Darwin</li>
197 * <li>AET - Australia/Sydney</li>
198 * <li>AGT - America/Argentina/Buenos_Aires</li>
199 * <li>ART - Africa/Cairo</li>
200 * <li>AST - America/Anchorage</li>
201 * <li>BET - America/Sao_Paulo</li>
202 * <li>BST - Asia/Dhaka</li>
203 * <li>CAT - Africa/Harare</li>
204 * <li>CNT - America/St_Johns</li>
205 * <li>CST - America/Chicago</li>
206 * <li>CTT - Asia/Shanghai</li>
207 * <li>EAT - Africa/Addis_Ababa</li>
208 * <li>ECT - Europe/Paris</li>
209 * <li>IET - America/Indiana/Indianapolis</li>
210 * <li>IST - Asia/Kolkata</li>
211 * <li>JST - Asia/Tokyo</li>
212 * <li>MIT - Pacific/Apia</li>
213 * <li>NET - Asia/Yerevan</li>
214 * <li>NST - Pacific/Auckland</li>
215 * <li>PLT - Asia/Karachi</li>
216 * <li>PNT - America/Phoenix</li>
217 * <li>PRT - America/Puerto_Rico</li>
218 * <li>PST - America/Los_Angeles</li>
219 * <li>SST - Pacific/Guadalcanal</li>
220 * <li>VST - Asia/Ho_Chi_Minh</li>
221 * </ul>
222 * The map is unmodifiable.
223 */
224 public static final Map<String, String> SHORT_IDS = Map.ofEntries(
225 entry("ACT", "Australia/Darwin"),
226 entry("AET", "Australia/Sydney"),
227 entry("AGT", "America/Argentina/Buenos_Aires"),
228 entry("ART", "Africa/Cairo"),
229 entry("AST", "America/Anchorage"),
230 entry("BET", "America/Sao_Paulo"),
231 entry("BST", "Asia/Dhaka"),
232 entry("CAT", "Africa/Harare"),
233 entry("CNT", "America/St_Johns"),
234 entry("CST", "America/Chicago"),
235 entry("CTT", "Asia/Shanghai"),
236 entry("EAT", "Africa/Addis_Ababa"),
237 entry("ECT", "Europe/Paris"),
238 entry("IET", "America/Indiana/Indianapolis"),
239 entry("IST", "Asia/Kolkata"),
240 entry("JST", "Asia/Tokyo"),
241 entry("MIT", "Pacific/Apia"),
242 entry("NET", "Asia/Yerevan"),
243 entry("NST", "Pacific/Auckland"),
244 entry("PLT", "Asia/Karachi"),
245 entry("PNT", "America/Phoenix"),
246 entry("PRT", "America/Puerto_Rico"),
247 entry("PST", "America/Los_Angeles"),
248 entry("SST", "Pacific/Guadalcanal"),
249 entry("VST", "Asia/Ho_Chi_Minh"),
250 entry("EST", "-05:00"),
251 entry("MST", "-07:00"),
252 entry("HST", "-10:00")
253 );
254 /**
255 * Serialization version.
256 */
257 private static final long serialVersionUID = 8352817235686L;
258
259 //-----------------------------------------------------------------------
260 /**
261 * Gets the system default time-zone.
262 * <p>
263 * This queries {@link TimeZone#getDefault()} to find the default time-zone
264 * and converts it to a {@code ZoneId}. If the system default time-zone is changed,
265 * then the result of this method will also change.
266 *
267 * @return the zone ID, not null
268 * @throws DateTimeException if the converted zone ID has an invalid format
269 * @throws ZoneRulesException if the converted zone region ID cannot be found
270 */
271 public static ZoneId systemDefault() {
272 return TimeZone.getDefault().toZoneId();
273 }
274
275 /**
276 * Gets the set of available zone IDs.
277 * <p>
278 * This set includes the string form of all available region-based IDs.
279 * Offset-based zone IDs are not included in the returned set.
280 * The ID can be passed to {@link #of(String)} to create a {@code ZoneId}.
281 * <p>
282 * The set of zone IDs can increase over time, although in a typical application
283 * the set of IDs is fixed. Each call to this method is thread-safe.
284 *
285 * @return a modifiable copy of the set of zone IDs, not null
286 */
287 public static Set<String> getAvailableZoneIds() {
288 return new HashSet<String>(ZoneRulesProvider.getAvailableZoneIds());
289 }
290
291 //-----------------------------------------------------------------------
292 /**
293 * Obtains an instance of {@code ZoneId} using its ID using a map
294 * of aliases to supplement the standard zone IDs.
295 * <p>
296 * Many users of time-zones use short abbreviations, such as PST for
297 * 'Pacific Standard Time' and PDT for 'Pacific Daylight Time'.
298 * These abbreviations are not unique, and so cannot be used as IDs.
299 * This method allows a map of string to time-zone to be setup and reused
300 * within an application.
301 *
302 * @param zoneId the time-zone ID, not null
303 * @param aliasMap a map of alias zone IDs (typically abbreviations) to real zone IDs, not null
304 * @return the zone ID, not null
305 * @throws DateTimeException if the zone ID has an invalid format
306 * @throws ZoneRulesException if the zone ID is a region ID that cannot be found
307 */
308 public static ZoneId of(String zoneId, Map<String, String> aliasMap) {
309 Objects.requireNonNull(zoneId, "zoneId");
310 Objects.requireNonNull(aliasMap, "aliasMap");
311 String id = Objects.requireNonNullElse(aliasMap.get(zoneId), zoneId);
312 return of(id);
313 }
314
315 /**
316 * Obtains an instance of {@code ZoneId} from an ID ensuring that the
317 * ID is valid and available for use.
318 * <p>
319 * This method parses the ID producing a {@code ZoneId} or {@code ZoneOffset}.
320 * A {@code ZoneOffset} is returned if the ID is 'Z', or starts with '+' or '-'.
321 * The result will always be a valid ID for which {@link ZoneRules} can be obtained.
322 * <p>
323 * Parsing matches the zone ID step by step as follows.
324 * <ul>
325 * <li>If the zone ID equals 'Z', the result is {@code ZoneOffset.UTC}.
326 * <li>If the zone ID consists of a single letter, the zone ID is invalid
327 * and {@code DateTimeException} is thrown.
328 * <li>If the zone ID starts with '+' or '-', the ID is parsed as a
329 * {@code ZoneOffset} using {@link ZoneOffset#of(String)}.
330 * <li>If the zone ID equals 'GMT', 'UTC' or 'UT' then the result is a {@code ZoneId}
331 * with the same ID and rules equivalent to {@code ZoneOffset.UTC}.
332 * <li>If the zone ID starts with 'UTC+', 'UTC-', 'GMT+', 'GMT-', 'UT+' or 'UT-'
333 * then the ID is a prefixed offset-based ID. The ID is split in two, with
334 * a two or three letter prefix and a suffix starting with the sign.
335 * The suffix is parsed as a {@link ZoneOffset#of(String) ZoneOffset}.
336 * The result will be a {@code ZoneId} with the specified UTC/GMT/UT prefix
337 * and the normalized offset ID as per {@link ZoneOffset#getId()}.
338 * The rules of the returned {@code ZoneId} will be equivalent to the
339 * parsed {@code ZoneOffset}.
340 * <li>All other IDs are parsed as region-based zone IDs. Region IDs must
341 * match the regular expression <code>[A-Za-z][A-Za-z0-9~/._+-]+</code>
342 * otherwise a {@code DateTimeException} is thrown. If the zone ID is not
343 * in the configured set of IDs, {@code ZoneRulesException} is thrown.
344 * The detailed format of the region ID depends on the group supplying the data.
345 * The default set of data is supplied by the IANA Time Zone Database (TZDB).
346 * This has region IDs of the form '{area}/{city}', such as 'Europe/Paris' or 'America/New_York'.
347 * This is compatible with most IDs from {@link java.util.TimeZone}.
348 * </ul>
349 *
350 * @param zoneId the time-zone ID, not null
351 * @return the zone ID, not null
352 * @throws DateTimeException if the zone ID has an invalid format
353 * @throws ZoneRulesException if the zone ID is a region ID that cannot be found
354 */
355 public static ZoneId of(String zoneId) {
356 return of(zoneId, true);
357 }
358
359 /**
360 * Obtains an instance of {@code ZoneId} wrapping an offset.
361 * <p>
362 * If the prefix is "GMT", "UTC", or "UT" a {@code ZoneId}
363 * with the prefix and the non-zero offset is returned.
364 * If the prefix is empty {@code ""} the {@code ZoneOffset} is returned.
365 *
366 * @param prefix the time-zone ID, not null
367 * @param offset the offset, not null
368 * @return the zone ID, not null
369 * @throws IllegalArgumentException if the prefix is not one of
370 * "GMT", "UTC", or "UT", or ""
371 */
372 public static ZoneId ofOffset(String prefix, ZoneOffset offset) {
373 Objects.requireNonNull(prefix, "prefix");
374 Objects.requireNonNull(offset, "offset");
375 if (prefix.isEmpty()) {
376 return offset;
377 }
378
379 if (!prefix.equals("GMT") && !prefix.equals("UTC") && !prefix.equals("UT")) {
380 throw new IllegalArgumentException("prefix should be GMT, UTC or UT, is: " + prefix);
381 }
382
383 if (offset.getTotalSeconds() != 0) {
384 prefix = prefix.concat(offset.getId());
385 }
386 return new ZoneRegion(prefix, offset.getRules());
387 }
388
389 /**
390 * Parses the ID, taking a flag to indicate whether {@code ZoneRulesException}
391 * should be thrown or not, used in deserialization.
392 *
393 * @param zoneId the time-zone ID, not null
394 * @param checkAvailable whether to check if the zone ID is available
395 * @return the zone ID, not null
396 * @throws DateTimeException if the ID format is invalid
397 * @throws ZoneRulesException if checking availability and the ID cannot be found
398 */
399 static ZoneId of(String zoneId, boolean checkAvailable) {
400 Objects.requireNonNull(zoneId, "zoneId");
401 if (zoneId.length() <= 1 || zoneId.startsWith("+") || zoneId.startsWith("-")) {
402 return ZoneOffset.of(zoneId);
403 } else if (zoneId.startsWith("UTC") || zoneId.startsWith("GMT")) {
404 return ofWithPrefix(zoneId, 3, checkAvailable);
405 } else if (zoneId.startsWith("UT")) {
406 return ofWithPrefix(zoneId, 2, checkAvailable);
407 }
408 return ZoneRegion.ofId(zoneId, checkAvailable);
409 }
410
411 /**
412 * Parse once a prefix is established.
413 *
414 * @param zoneId the time-zone ID, not null
415 * @param prefixLength the length of the prefix, 2 or 3
416 * @return the zone ID, not null
417 * @throws DateTimeException if the zone ID has an invalid format
418 */
419 private static ZoneId ofWithPrefix(String zoneId, int prefixLength, boolean checkAvailable) {
420 String prefix = zoneId.substring(0, prefixLength);
421 if (zoneId.length() == prefixLength) {
422 return ofOffset(prefix, ZoneOffset.UTC);
423 }
424 if (zoneId.charAt(prefixLength) != '+' && zoneId.charAt(prefixLength) != '-') {
425 return ZoneRegion.ofId(zoneId, checkAvailable); // drop through to ZoneRulesProvider
426 }
427 try {
428 ZoneOffset offset = ZoneOffset.of(zoneId.substring(prefixLength));
429 if (offset == ZoneOffset.UTC) {
430 return ofOffset(prefix, offset);
431 }
432 return ofOffset(prefix, offset);
433 } catch (DateTimeException ex) {
434 throw new DateTimeException("Invalid ID for offset-based ZoneId: " + zoneId, ex);
435 }
436 }
437
438 //-----------------------------------------------------------------------
439 /**
440 * Obtains an instance of {@code ZoneId} from a temporal object.
441 * <p>
442 * This obtains a zone based on the specified temporal.
443 * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
444 * which this factory converts to an instance of {@code ZoneId}.
445 * <p>
446 * A {@code TemporalAccessor} represents some form of date and time information.
447 * This factory converts the arbitrary temporal object to an instance of {@code ZoneId}.
448 * <p>
449 * The conversion will try to obtain the zone in a way that favours region-based
450 * zones over offset-based zones using {@link TemporalQueries#zone()}.
451 * <p>
452 * This method matches the signature of the functional interface {@link TemporalQuery}
453 * allowing it to be used as a query via method reference, {@code ZoneId::from}.
454 *
455 * @param temporal the temporal object to convert, not null
456 * @return the zone ID, not null
457 * @throws DateTimeException if unable to convert to a {@code ZoneId}
458 */
459 public static ZoneId from(TemporalAccessor temporal) {
460 ZoneId obj = temporal.query(TemporalQueries.zone());
461 if (obj == null) {
462 throw new DateTimeException("Unable to obtain ZoneId from TemporalAccessor: " +
463 temporal + " of type " + temporal.getClass().getName());
464 }
465 return obj;
466 }
467
468 //-----------------------------------------------------------------------
469 /**
470 * Constructor only accessible within the package.
471 */
472 ZoneId() {
473 if (getClass() != ZoneOffset.class && getClass() != ZoneRegion.class) {
474 throw new AssertionError("Invalid subclass");
475 }
476 }
477
478 //-----------------------------------------------------------------------
479 /**
480 * Gets the unique time-zone ID.
481 * <p>
482 * This ID uniquely defines this object.
483 * The format of an offset based ID is defined by {@link ZoneOffset#getId()}.
484 *
485 * @return the time-zone unique ID, not null
486 */
487 public abstract String getId();
488
489 //-----------------------------------------------------------------------
490 /**
491 * Gets the textual representation of the zone, such as 'British Time' or
492 * '+02:00'.
493 * <p>
494 * This returns the textual name used to identify the time-zone ID,
495 * suitable for presentation to the user.
496 * The parameters control the style of the returned text and the locale.
497 * <p>
498 * If no textual mapping is found then the {@link #getId() full ID} is returned.
499 *
500 * @param style the length of the text required, not null
501 * @param locale the locale to use, not null
502 * @return the text value of the zone, not null
503 */
504 public String getDisplayName(TextStyle style, Locale locale) {
505 return new DateTimeFormatterBuilder().appendZoneText(style).toFormatter(locale).format(toTemporal());
506 }
507
508 /**
509 * Converts this zone to a {@code TemporalAccessor}.
510 * <p>
511 * A {@code ZoneId} can be fully represented as a {@code TemporalAccessor}.
512 * However, the interface is not implemented by this class as most of the
513 * methods on the interface have no meaning to {@code ZoneId}.
514 * <p>
515 * The returned temporal has no supported fields, with the query method
516 * supporting the return of the zone using {@link TemporalQueries#zoneId()}.
517 *
518 * @return a temporal equivalent to this zone, not null
519 */
520 private TemporalAccessor toTemporal() {
521 return new TemporalAccessor() {
522 @Override
523 public boolean isSupported(TemporalField field) {
524 return false;
525 }
526 @Override
527 public long getLong(TemporalField field) {
528 throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
529 }
530 @SuppressWarnings("unchecked")
531 @Override
532 public <R> R query(TemporalQuery<R> query) {
533 if (query == TemporalQueries.zoneId()) {
534 return (R) ZoneId.this;
535 }
536 return TemporalAccessor.super.query(query);
537 }
538 };
539 }
540
541 //-----------------------------------------------------------------------
542 /**
543 * Gets the time-zone rules for this ID allowing calculations to be performed.
544 * <p>
545 * The rules provide the functionality associated with a time-zone,
546 * such as finding the offset for a given instant or local date-time.
547 * <p>
548 * A time-zone can be invalid if it is deserialized in a Java Runtime which
549 * does not have the same rules loaded as the Java Runtime that stored it.
550 * In this case, calling this method will throw a {@code ZoneRulesException}.
551 * <p>
552 * The rules are supplied by {@link ZoneRulesProvider}. An advanced provider may
553 * support dynamic updates to the rules without restarting the Java Runtime.
554 * If so, then the result of this method may change over time.
555 * Each individual call will be still remain thread-safe.
556 * <p>
557 * {@link ZoneOffset} will always return a set of rules where the offset never changes.
558 *
559 * @return the rules, not null
560 * @throws ZoneRulesException if no rules are available for this ID
561 */
562 public abstract ZoneRules getRules();
563
564 /**
565 * Normalizes the time-zone ID, returning a {@code ZoneOffset} where possible.
566 * <p>
567 * The returns a normalized {@code ZoneId} that can be used in place of this ID.
568 * The result will have {@code ZoneRules} equivalent to those returned by this object,
569 * however the ID returned by {@code getId()} may be different.
570 * <p>
571 * The normalization checks if the rules of this {@code ZoneId} have a fixed offset.
572 * If they do, then the {@code ZoneOffset} equal to that offset is returned.
573 * Otherwise {@code this} is returned.
574 *
575 * @return the time-zone unique ID, not null
576 */
577 public ZoneId normalized() {
578 try {
579 ZoneRules rules = getRules();
580 if (rules.isFixedOffset()) {
581 return rules.getOffset(Instant.EPOCH);
582 }
583 } catch (ZoneRulesException ex) {
584 // invalid ZoneRegion is not important to this method
585 }
586 return this;
587 }
588
589 //-----------------------------------------------------------------------
590 /**
591 * Checks if this time-zone ID is equal to another time-zone ID.
592 * <p>
593 * The comparison is based on the ID.
594 *
595 * @param obj the object to check, null returns false
596 * @return true if this is equal to the other time-zone ID
597 */
598 @Override
599 public boolean equals(Object obj) {
600 if (this == obj) {
601 return true;
602 }
603 if (obj instanceof ZoneId) {
604 ZoneId other = (ZoneId) obj;
605 return getId().equals(other.getId());
606 }
607 return false;
608 }
609
610 /**
611 * A hash code for this time-zone ID.
612 *
613 * @return a suitable hash code
614 */
615 @Override
616 public int hashCode() {
617 return getId().hashCode();
618 }
619
620 //-----------------------------------------------------------------------
621 /**
622 * Defend against malicious streams.
623 *
624 * @param s the stream to read
625 * @throws InvalidObjectException always
626 */
627 private void readObject(ObjectInputStream s) throws InvalidObjectException {
628 throw new InvalidObjectException("Deserialization via serialization delegate");
629 }
630
631 /**
632 * Outputs this zone as a {@code String}, using the ID.
633 *
634 * @return a string representation of this time-zone ID, not null
635 */
636 @Override
637 public String toString() {
638 return getId();
639 }
640
641 //-----------------------------------------------------------------------
642 /**
643 * Writes the object using a
644 * <a href="{@docRoot}/serialized-form.html#java.time.Ser">dedicated serialized form</a>.
645 * @serialData
646 * <pre>
647 * out.writeByte(7); // identifies a ZoneId (not ZoneOffset)
648 * out.writeUTF(getId());
649 * </pre>
650 * <p>
651 * When read back in, the {@code ZoneId} will be created as though using
652 * {@link #of(String)}, but without any exception in the case where the
653 * ID has a valid format, but is not in the known set of region-based IDs.
654 *
655 * @return the instance of {@code Ser}, not null
656 */
657 // this is here for serialization Javadoc
658 private Object writeReplace() {
659 return new Ser(Ser.ZONE_REGION_TYPE, this);
660 }
661
662 abstract void write(DataOutput out) throws IOException;
663
664 }