1 /*
2 * Copyright (c) 2012, 2013, 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 * 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.Collections;
80 import java.util.HashMap;
81 import java.util.Locale;
82 import java.util.Map;
83 import java.util.Objects;
84 import java.util.Set;
85 import java.util.TimeZone;
86
87 /**
88 * A time-zone ID, such as {@code Europe/Paris}.
89 * <p>
90 * A {@code ZoneId} is used to identify the rules used to convert between
91 * an {@link Instant} and a {@link LocalDateTime}.
92 * There are two distinct types of ID:
93 * <ul>
94 * <li>Fixed offsets - a fully resolved offset from UTC/Greenwich, that uses
95 * the same offset for all local date-times
96 * <li>Geographical regions - an area where a specific set of rules for finding
97 * the offset from UTC/Greenwich apply
98 * </ul>
99 * Most fixed offsets are represented by {@link ZoneOffset}.
100 * Calling {@link #normalized()} on any {@code ZoneId} will ensure that a
101 * fixed offset ID will be represented as a {@code ZoneOffset}.
102 * <p>
103 * The actual rules, describing when and how the offset changes, are defined by {@link ZoneRules}.
104 * This class is simply an ID used to obtain the underlying rules.
105 * This approach is taken because rules are defined by governments and change
106 * frequently, whereas the ID is stable.
107 * <p>
108 * The distinction has other effects. Serializing the {@code ZoneId} will only send
109 * the ID, whereas serializing the rules sends the entire data set.
110 * Similarly, a comparison of two IDs only examines the ID, whereas
111 * a comparison of two rules examines the entire data set.
112 *
113 * <h3>Time-zone IDs</h3>
114 * The ID is unique within the system.
115 * There are three types of ID.
116 * <p>
117 * The simplest type of ID is that from {@code ZoneOffset}.
118 * This consists of 'Z' and IDs starting with '+' or '-'.
119 * <p>
120 * The next type of ID are offset-style IDs with some form of prefix,
121 * such as 'GMT+2' or 'UTC+01:00'.
122 * The recognised prefixes are 'UTC', 'GMT' and 'UT'.
123 * The offset is the suffix and will be normalized during creation.
124 * These IDs can be normalized to a {@code ZoneOffset} using {@code normalized()}.
125 * <p>
126 * The third type of ID are region-based IDs. A region-based ID must be of
127 * two or more characters, and not start with 'UTC', 'GMT', 'UT' '+' or '-'.
128 * Region-based IDs are defined by configuration, see {@link ZoneRulesProvider}.
129 * The configuration focuses on providing the lookup from the ID to the
130 * underlying {@code ZoneRules}.
131 * <p>
132 * Time-zone rules are defined by governments and change frequently.
133 * There are a number of organizations, known here as groups, that monitor
134 * time-zone changes and collate them.
135 * The default group is the IANA Time Zone Database (TZDB).
136 * Other organizations include IATA (the airline industry body) and Microsoft.
137 * <p>
138 * Each group defines its own format for the region ID it provides.
139 * The TZDB group defines IDs such as 'Europe/London' or 'America/New_York'.
140 * TZDB IDs take precedence over other groups.
141 * <p>
142 * It is strongly recommended that the group name is included in all IDs supplied by
143 * groups other than TZDB to avoid conflicts. For example, IATA airline time-zone
144 * region IDs are typically the same as the three letter airport code.
145 * However, the airport of Utrecht has the code 'UTC', which is obviously a conflict.
146 * The recommended format for region IDs from groups other than TZDB is 'group~region'.
147 * Thus if IATA data were defined, Utrecht airport would be 'IATA~UTC'.
148 *
149 * <h3>Serialization</h3>
150 * This class can be serialized and stores the string zone ID in the external form.
151 * The {@code ZoneOffset} subclass uses a dedicated format that only stores the
152 * offset from UTC/Greenwich.
153 * <p>
154 * A {@code ZoneId} can be deserialized in a Java Runtime where the ID is unknown.
155 * For example, if a server-side Java Runtime has been updated with a new zone ID, but
156 * the client-side Java Runtime has not been updated. In this case, the {@code ZoneId}
157 * object will exist, and can be queried using {@code getId}, {@code equals},
158 * {@code hashCode}, {@code toString}, {@code getDisplayName} and {@code normalized}.
159 * However, any call to {@code getRules} will fail with {@code ZoneRulesException}.
160 * This approach is designed to allow a {@link ZonedDateTime} to be loaded and
161 * queried, but not modified, on a Java Runtime with incomplete time-zone information.
162 *
163 * <p>
164 * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
165 * class; use of identity-sensitive operations (including reference equality
166 * ({@code ==}), identity hash code, or synchronization) on instances of
167 * {@code ZoneId} may have unpredictable results and should be avoided.
168 * The {@code equals} method should be used for comparisons.
169 *
170 * @implSpec
171 * This abstract class has two implementations, both of which are immutable and thread-safe.
172 * One implementation models region-based IDs, the other is {@code ZoneOffset} modelling
173 * offset-based IDs. This difference is visible in serialization.
174 *
175 * @since 1.8
176 */
177 public abstract class ZoneId implements Serializable {
178
179 /**
180 * A map of zone overrides to enable the short time-zone names to be used.
181 * <p>
182 * Use of short zone IDs has been deprecated in {@code java.util.TimeZone}.
183 * This map allows the IDs to continue to be used via the
184 * {@link #of(String, Map)} factory method.
185 * <p>
186 * This map contains a mapping of the IDs that is in line with TZDB 2005r and
187 * later, where 'EST', 'MST' and 'HST' map to IDs which do not include daylight
188 * savings.
189 * <p>
190 * This maps as follows:
191 * <ul>
192 * <li>EST - -05:00</li>
193 * <li>HST - -10:00</li>
194 * <li>MST - -07:00</li>
195 * <li>ACT - Australia/Darwin</li>
196 * <li>AET - Australia/Sydney</li>
197 * <li>AGT - America/Argentina/Buenos_Aires</li>
198 * <li>ART - Africa/Cairo</li>
199 * <li>AST - America/Anchorage</li>
200 * <li>BET - America/Sao_Paulo</li>
201 * <li>BST - Asia/Dhaka</li>
202 * <li>CAT - Africa/Harare</li>
203 * <li>CNT - America/St_Johns</li>
204 * <li>CST - America/Chicago</li>
205 * <li>CTT - Asia/Shanghai</li>
206 * <li>EAT - Africa/Addis_Ababa</li>
207 * <li>ECT - Europe/Paris</li>
208 * <li>IET - America/Indiana/Indianapolis</li>
209 * <li>IST - Asia/Kolkata</li>
210 * <li>JST - Asia/Tokyo</li>
211 * <li>MIT - Pacific/Apia</li>
212 * <li>NET - Asia/Yerevan</li>
213 * <li>NST - Pacific/Auckland</li>
214 * <li>PLT - Asia/Karachi</li>
215 * <li>PNT - America/Phoenix</li>
216 * <li>PRT - America/Puerto_Rico</li>
217 * <li>PST - America/Los_Angeles</li>
218 * <li>SST - Pacific/Guadalcanal</li>
219 * <li>VST - Asia/Ho_Chi_Minh</li>
220 * </ul>
221 * The map is unmodifiable.
222 */
223 public static final Map<String, String> SHORT_IDS;
224 static {
225 Map<String, String> map = new HashMap<>(64);
226 map.put("ACT", "Australia/Darwin");
227 map.put("AET", "Australia/Sydney");
228 map.put("AGT", "America/Argentina/Buenos_Aires");
229 map.put("ART", "Africa/Cairo");
230 map.put("AST", "America/Anchorage");
231 map.put("BET", "America/Sao_Paulo");
232 map.put("BST", "Asia/Dhaka");
233 map.put("CAT", "Africa/Harare");
234 map.put("CNT", "America/St_Johns");
235 map.put("CST", "America/Chicago");
236 map.put("CTT", "Asia/Shanghai");
237 map.put("EAT", "Africa/Addis_Ababa");
238 map.put("ECT", "Europe/Paris");
239 map.put("IET", "America/Indiana/Indianapolis");
240 map.put("IST", "Asia/Kolkata");
241 map.put("JST", "Asia/Tokyo");
242 map.put("MIT", "Pacific/Apia");
243 map.put("NET", "Asia/Yerevan");
244 map.put("NST", "Pacific/Auckland");
245 map.put("PLT", "Asia/Karachi");
246 map.put("PNT", "America/Phoenix");
247 map.put("PRT", "America/Puerto_Rico");
248 map.put("PST", "America/Los_Angeles");
249 map.put("SST", "Pacific/Guadalcanal");
250 map.put("VST", "Asia/Ho_Chi_Minh");
251 map.put("EST", "-05:00");
252 map.put("MST", "-07:00");
253 map.put("HST", "-10:00");
254 SHORT_IDS = Collections.unmodifiableMap(map);
255 }
256 /**
257 * Serialization version.
258 */
259 private static final long serialVersionUID = 8352817235686L;
260
261 //-----------------------------------------------------------------------
262 /**
263 * Gets the system default time-zone.
264 * <p>
265 * This queries {@link TimeZone#getDefault()} to find the default time-zone
266 * and converts it to a {@code ZoneId}. If the system default time-zone is changed,
267 * then the result of this method will also change.
268 *
269 * @return the zone ID, not null
270 * @throws DateTimeException if the converted zone ID has an invalid format
271 * @throws ZoneRulesException if the converted zone region ID cannot be found
272 */
273 public static ZoneId systemDefault() {
274 return TimeZone.getDefault().toZoneId();
275 }
276
277 /**
278 * Gets the set of available zone IDs.
279 * <p>
280 * This set includes the string form of all available region-based IDs.
281 * Offset-based zone IDs are not included in the returned set.
282 * The ID can be passed to {@link #of(String)} to create a {@code ZoneId}.
283 * <p>
284 * The set of zone IDs can increase over time, although in a typical application
285 * the set of IDs is fixed. Each call to this method is thread-safe.
286 *
287 * @return a modifiable copy of the set of zone IDs, not null
288 */
289 public static Set<String> getAvailableZoneIds() {
290 return ZoneRulesProvider.getAvailableZoneIds();
291 }
292
293 //-----------------------------------------------------------------------
294 /**
295 * Obtains an instance of {@code ZoneId} using its ID using a map
296 * of aliases to supplement the standard zone IDs.
297 * <p>
298 * Many users of time-zones use short abbreviations, such as PST for
299 * 'Pacific Standard Time' and PDT for 'Pacific Daylight Time'.
300 * These abbreviations are not unique, and so cannot be used as IDs.
301 * This method allows a map of string to time-zone to be setup and reused
302 * within an application.
303 *
304 * @param zoneId the time-zone ID, not null
305 * @param aliasMap a map of alias zone IDs (typically abbreviations) to real zone IDs, not null
306 * @return the zone ID, not null
307 * @throws DateTimeException if the zone ID has an invalid format
308 * @throws ZoneRulesException if the zone ID is a region ID that cannot be found
309 */
310 public static ZoneId of(String zoneId, Map<String, String> aliasMap) {
311 Objects.requireNonNull(zoneId, "zoneId");
312 Objects.requireNonNull(aliasMap, "aliasMap");
313 String id = Objects.requireNonNullElse(aliasMap.get(zoneId), zoneId);
314 return of(id);
315 }
316
317 /**
318 * Obtains an instance of {@code ZoneId} from an ID ensuring that the
319 * ID is valid and available for use.
320 * <p>
321 * This method parses the ID producing a {@code ZoneId} or {@code ZoneOffset}.
322 * A {@code ZoneOffset} is returned if the ID is 'Z', or starts with '+' or '-'.
323 * The result will always be a valid ID for which {@link ZoneRules} can be obtained.
324 * <p>
325 * Parsing matches the zone ID step by step as follows.
326 * <ul>
327 * <li>If the zone ID equals 'Z', the result is {@code ZoneOffset.UTC}.
328 * <li>If the zone ID consists of a single letter, the zone ID is invalid
329 * and {@code DateTimeException} is thrown.
330 * <li>If the zone ID starts with '+' or '-', the ID is parsed as a
331 * {@code ZoneOffset} using {@link ZoneOffset#of(String)}.
332 * <li>If the zone ID equals 'GMT', 'UTC' or 'UT' then the result is a {@code ZoneId}
333 * with the same ID and rules equivalent to {@code ZoneOffset.UTC}.
334 * <li>If the zone ID starts with 'UTC+', 'UTC-', 'GMT+', 'GMT-', 'UT+' or 'UT-'
335 * then the ID is a prefixed offset-based ID. The ID is split in two, with
336 * a two or three letter prefix and a suffix starting with the sign.
337 * The suffix is parsed as a {@link ZoneOffset#of(String) ZoneOffset}.
338 * The result will be a {@code ZoneId} with the specified UTC/GMT/UT prefix
339 * and the normalized offset ID as per {@link ZoneOffset#getId()}.
340 * The rules of the returned {@code ZoneId} will be equivalent to the
341 * parsed {@code ZoneOffset}.
342 * <li>All other IDs are parsed as region-based zone IDs. Region IDs must
343 * match the regular expression <code>[A-Za-z][A-Za-z0-9~/._+-]+</code>
344 * otherwise a {@code DateTimeException} is thrown. If the zone ID is not
345 * in the configured set of IDs, {@code ZoneRulesException} is thrown.
346 * The detailed format of the region ID depends on the group supplying the data.
347 * The default set of data is supplied by the IANA Time Zone Database (TZDB).
348 * This has region IDs of the form '{area}/{city}', such as 'Europe/Paris' or 'America/New_York'.
349 * This is compatible with most IDs from {@link java.util.TimeZone}.
350 * </ul>
351 *
352 * @param zoneId the time-zone ID, not null
353 * @return the zone ID, not null
354 * @throws DateTimeException if the zone ID has an invalid format
355 * @throws ZoneRulesException if the zone ID is a region ID that cannot be found
356 */
357 public static ZoneId of(String zoneId) {
358 return of(zoneId, true);
359 }
360
361 /**
362 * Obtains an instance of {@code ZoneId} wrapping an offset.
363 * <p>
364 * If the prefix is "GMT", "UTC", or "UT" a {@code ZoneId}
365 * with the prefix and the non-zero offset is returned.
366 * If the prefix is empty {@code ""} the {@code ZoneOffset} is returned.
367 *
368 * @param prefix the time-zone ID, not null
369 * @param offset the offset, not null
370 * @return the zone ID, not null
371 * @throws IllegalArgumentException if the prefix is not one of
372 * "GMT", "UTC", or "UT", or ""
373 */
374 public static ZoneId ofOffset(String prefix, ZoneOffset offset) {
375 Objects.requireNonNull(prefix, "prefix");
376 Objects.requireNonNull(offset, "offset");
377 if (prefix.length() == 0) {
378 return offset;
379 }
380
381 if (!prefix.equals("GMT") && !prefix.equals("UTC") && !prefix.equals("UT")) {
382 throw new IllegalArgumentException("prefix should be GMT, UTC or UT, is: " + prefix);
383 }
384
385 if (offset.getTotalSeconds() != 0) {
386 prefix = prefix.concat(offset.getId());
387 }
388 return new ZoneRegion(prefix, offset.getRules());
389 }
390
391 /**
392 * Parses the ID, taking a flag to indicate whether {@code ZoneRulesException}
393 * should be thrown or not, used in deserialization.
394 *
395 * @param zoneId the time-zone ID, not null
396 * @param checkAvailable whether to check if the zone ID is available
397 * @return the zone ID, not null
398 * @throws DateTimeException if the ID format is invalid
399 * @throws ZoneRulesException if checking availability and the ID cannot be found
400 */
401 static ZoneId of(String zoneId, boolean checkAvailable) {
402 Objects.requireNonNull(zoneId, "zoneId");
403 if (zoneId.length() <= 1 || zoneId.startsWith("+") || zoneId.startsWith("-")) {
404 return ZoneOffset.of(zoneId);
405 } else if (zoneId.startsWith("UTC") || zoneId.startsWith("GMT")) {
406 return ofWithPrefix(zoneId, 3, checkAvailable);
407 } else if (zoneId.startsWith("UT")) {
408 return ofWithPrefix(zoneId, 2, checkAvailable);
409 }
410 return ZoneRegion.ofId(zoneId, checkAvailable);
411 }
412
413 /**
414 * Parse once a prefix is established.
415 *
416 * @param zoneId the time-zone ID, not null
417 * @param prefixLength the length of the prefix, 2 or 3
418 * @return the zone ID, not null
419 * @throws DateTimeException if the zone ID has an invalid format
420 */
421 private static ZoneId ofWithPrefix(String zoneId, int prefixLength, boolean checkAvailable) {
422 String prefix = zoneId.substring(0, prefixLength);
423 if (zoneId.length() == prefixLength) {
424 return ofOffset(prefix, ZoneOffset.UTC);
425 }
426 if (zoneId.charAt(prefixLength) != '+' && zoneId.charAt(prefixLength) != '-') {
427 return ZoneRegion.ofId(zoneId, checkAvailable); // drop through to ZoneRulesProvider
428 }
429 try {
430 ZoneOffset offset = ZoneOffset.of(zoneId.substring(prefixLength));
431 if (offset == ZoneOffset.UTC) {
432 return ofOffset(prefix, offset);
433 }
434 return ofOffset(prefix, offset);
435 } catch (DateTimeException ex) {
436 throw new DateTimeException("Invalid ID for offset-based ZoneId: " + zoneId, ex);
437 }
438 }
439
440 //-----------------------------------------------------------------------
441 /**
442 * Obtains an instance of {@code ZoneId} from a temporal object.
443 * <p>
444 * This obtains a zone based on the specified temporal.
445 * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
446 * which this factory converts to an instance of {@code ZoneId}.
447 * <p>
448 * A {@code TemporalAccessor} represents some form of date and time information.
449 * This factory converts the arbitrary temporal object to an instance of {@code ZoneId}.
450 * <p>
451 * The conversion will try to obtain the zone in a way that favours region-based
452 * zones over offset-based zones using {@link TemporalQueries#zone()}.
453 * <p>
454 * This method matches the signature of the functional interface {@link TemporalQuery}
455 * allowing it to be used as a query via method reference, {@code ZoneId::from}.
456 *
457 * @param temporal the temporal object to convert, not null
458 * @return the zone ID, not null
459 * @throws DateTimeException if unable to convert to a {@code ZoneId}
460 */
461 public static ZoneId from(TemporalAccessor temporal) {
462 ZoneId obj = temporal.query(TemporalQueries.zone());
463 if (obj == null) {
464 throw new DateTimeException("Unable to obtain ZoneId from TemporalAccessor: " +
465 temporal + " of type " + temporal.getClass().getName());
466 }
467 return obj;
468 }
469
470 //-----------------------------------------------------------------------
471 /**
472 * Constructor only accessible within the package.
473 */
474 ZoneId() {
475 if (getClass() != ZoneOffset.class && getClass() != ZoneRegion.class) {
476 throw new AssertionError("Invalid subclass");
477 }
478 }
479
480 //-----------------------------------------------------------------------
481 /**
482 * Gets the unique time-zone ID.
483 * <p>
484 * This ID uniquely defines this object.
485 * The format of an offset based ID is defined by {@link ZoneOffset#getId()}.
486 *
487 * @return the time-zone unique ID, not null
488 */
489 public abstract String getId();
490
491 //-----------------------------------------------------------------------
492 /**
493 * Gets the textual representation of the zone, such as 'British Time' or
494 * '+02:00'.
495 * <p>
496 * This returns the textual name used to identify the time-zone ID,
497 * suitable for presentation to the user.
498 * The parameters control the style of the returned text and the locale.
499 * <p>
500 * If no textual mapping is found then the {@link #getId() full ID} is returned.
501 *
502 * @param style the length of the text required, not null
503 * @param locale the locale to use, not null
504 * @return the text value of the zone, not null
505 */
506 public String getDisplayName(TextStyle style, Locale locale) {
507 return new DateTimeFormatterBuilder().appendZoneText(style).toFormatter(locale).format(toTemporal());
508 }
509
510 /**
511 * Converts this zone to a {@code TemporalAccessor}.
512 * <p>
513 * A {@code ZoneId} can be fully represented as a {@code TemporalAccessor}.
514 * However, the interface is not implemented by this class as most of the
515 * methods on the interface have no meaning to {@code ZoneId}.
516 * <p>
517 * The returned temporal has no supported fields, with the query method
518 * supporting the return of the zone using {@link TemporalQueries#zoneId()}.
519 *
520 * @return a temporal equivalent to this zone, not null
521 */
522 private TemporalAccessor toTemporal() {
523 return new TemporalAccessor() {
524 @Override
525 public boolean isSupported(TemporalField field) {
526 return false;
527 }
528 @Override
529 public long getLong(TemporalField field) {
530 throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
531 }
532 @SuppressWarnings("unchecked")
533 @Override
534 public <R> R query(TemporalQuery<R> query) {
535 if (query == TemporalQueries.zoneId()) {
536 return (R) ZoneId.this;
537 }
538 return TemporalAccessor.super.query(query);
539 }
540 };
541 }
542
543 //-----------------------------------------------------------------------
544 /**
545 * Gets the time-zone rules for this ID allowing calculations to be performed.
546 * <p>
547 * The rules provide the functionality associated with a time-zone,
548 * such as finding the offset for a given instant or local date-time.
549 * <p>
550 * A time-zone can be invalid if it is deserialized in a Java Runtime which
551 * does not have the same rules loaded as the Java Runtime that stored it.
552 * In this case, calling this method will throw a {@code ZoneRulesException}.
553 * <p>
554 * The rules are supplied by {@link ZoneRulesProvider}. An advanced provider may
555 * support dynamic updates to the rules without restarting the Java Runtime.
556 * If so, then the result of this method may change over time.
557 * Each individual call will be still remain thread-safe.
558 * <p>
559 * {@link ZoneOffset} will always return a set of rules where the offset never changes.
560 *
561 * @return the rules, not null
562 * @throws ZoneRulesException if no rules are available for this ID
563 */
564 public abstract ZoneRules getRules();
565
566 /**
567 * Normalizes the time-zone ID, returning a {@code ZoneOffset} where possible.
568 * <p>
569 * The returns a normalized {@code ZoneId} that can be used in place of this ID.
570 * The result will have {@code ZoneRules} equivalent to those returned by this object,
571 * however the ID returned by {@code getId()} may be different.
572 * <p>
573 * The normalization checks if the rules of this {@code ZoneId} have a fixed offset.
574 * If they do, then the {@code ZoneOffset} equal to that offset is returned.
575 * Otherwise {@code this} is returned.
576 *
577 * @return the time-zone unique ID, not null
578 */
579 public ZoneId normalized() {
580 try {
581 ZoneRules rules = getRules();
582 if (rules.isFixedOffset()) {
583 return rules.getOffset(Instant.EPOCH);
584 }
585 } catch (ZoneRulesException ex) {
586 // invalid ZoneRegion is not important to this method
587 }
588 return this;
589 }
590
591 //-----------------------------------------------------------------------
592 /**
593 * Checks if this time-zone ID is equal to another time-zone ID.
594 * <p>
595 * The comparison is based on the ID.
596 *
597 * @param obj the object to check, null returns false
598 * @return true if this is equal to the other time-zone ID
599 */
600 @Override
601 public boolean equals(Object obj) {
602 if (this == obj) {
603 return true;
604 }
605 if (obj instanceof ZoneId) {
606 ZoneId other = (ZoneId) obj;
607 return getId().equals(other.getId());
608 }
609 return false;
610 }
611
612 /**
613 * A hash code for this time-zone ID.
614 *
615 * @return a suitable hash code
616 */
617 @Override
618 public int hashCode() {
619 return getId().hashCode();
620 }
621
622 //-----------------------------------------------------------------------
623 /**
624 * Defend against malicious streams.
625 *
626 * @param s the stream to read
627 * @throws InvalidObjectException always
628 */
629 private void readObject(ObjectInputStream s) throws InvalidObjectException {
630 throw new InvalidObjectException("Deserialization via serialization delegate");
631 }
632
633 /**
634 * Outputs this zone as a {@code String}, using the ID.
635 *
636 * @return a string representation of this time-zone ID, not null
637 */
638 @Override
639 public String toString() {
640 return getId();
641 }
642
643 //-----------------------------------------------------------------------
644 /**
645 * Writes the object using a
646 * <a href="../../serialized-form.html#java.time.Ser">dedicated serialized form</a>.
647 * @serialData
648 * <pre>
649 * out.writeByte(7); // identifies a ZoneId (not ZoneOffset)
650 * out.writeUTF(getId());
651 * </pre>
652 * <p>
653 * When read back in, the {@code ZoneId} will be created as though using
654 * {@link #of(String)}, but without any exception in the case where the
655 * ID has a valid format, but is not in the known set of region-based IDs.
656 *
657 * @return the instance of {@code Ser}, not null
658 */
659 // this is here for serialization Javadoc
660 private Object writeReplace() {
661 return new Ser(Ser.ZONE_REGION_TYPE, this);
662 }
663
664 abstract void write(DataOutput out) throws IOException;
665
666 }