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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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 static java.time.LocalTime.MINUTES_PER_HOUR;
65 import static java.time.LocalTime.SECONDS_PER_HOUR;
66 import static java.time.LocalTime.SECONDS_PER_MINUTE;
67 import static java.time.temporal.ChronoField.OFFSET_SECONDS;
68
69 import java.io.DataInput;
70 import java.io.DataOutput;
71 import java.io.IOException;
72 import java.io.InvalidObjectException;
73 import java.io.ObjectInputStream;
74 import java.io.Serializable;
75 import java.time.temporal.ChronoField;
76 import java.time.temporal.Temporal;
77 import java.time.temporal.TemporalAccessor;
78 import java.time.temporal.TemporalAdjuster;
79 import java.time.temporal.TemporalField;
80 import java.time.temporal.TemporalQueries;
81 import java.time.temporal.TemporalQuery;
82 import java.time.temporal.UnsupportedTemporalTypeException;
83 import java.time.temporal.ValueRange;
84 import java.time.zone.ZoneRules;
85 import java.util.Objects;
86 import java.util.concurrent.ConcurrentHashMap;
87 import java.util.concurrent.ConcurrentMap;
88
89 /**
90 * A time-zone offset from Greenwich/UTC, such as {@code +02:00}.
91 * <p>
92 * A time-zone offset is the amount of time that a time-zone differs from Greenwich/UTC.
93 * This is usually a fixed number of hours and minutes.
94 * <p>
95 * Different parts of the world have different time-zone offsets.
96 * The rules for how offsets vary by place and time of year are captured in the
97 * {@link ZoneId} class.
98 * <p>
99 * For example, Paris is one hour ahead of Greenwich/UTC in winter and two hours
100 * ahead in summer. The {@code ZoneId} instance for Paris will reference two
101 * {@code ZoneOffset} instances - a {@code +01:00} instance for winter,
102 * and a {@code +02:00} instance for summer.
103 * <p>
104 * In 2008, time-zone offsets around the world extended from -12:00 to +14:00.
105 * To prevent any problems with that range being extended, yet still provide
106 * validation, the range of offsets is restricted to -18:00 to 18:00 inclusive.
107 * <p>
108 * This class is designed for use with the ISO calendar system.
109 * The fields of hours, minutes and seconds make assumptions that are valid for the
110 * standard ISO definitions of those fields. This class may be used with other
111 * calendar systems providing the definition of the time fields matches those
112 * of the ISO calendar system.
113 * <p>
114 * Instances of {@code ZoneOffset} must be compared using {@link #equals}.
115 * Implementations may choose to cache certain common offsets, however
116 * applications must not rely on such caching.
117 *
118 * <p>
119 * This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
120 * class; use of identity-sensitive operations (including reference equality
121 * ({@code ==}), identity hash code, or synchronization) on instances of
122 * {@code ZoneOffset} may have unpredictable results and should be avoided.
123 * The {@code equals} method should be used for comparisons.
124 *
125 * @implSpec
126 * This class is immutable and thread-safe.
127 *
128 * @since 1.8
129 */
130 public final class ZoneOffset
131 extends ZoneId
132 implements TemporalAccessor, TemporalAdjuster, Comparable<ZoneOffset>, Serializable {
133
134 /** Cache of time-zone offset by offset in seconds. */
135 private static final ConcurrentMap<Integer, ZoneOffset> SECONDS_CACHE = new ConcurrentHashMap<>(16, 0.75f, 4);
136 /** Cache of time-zone offset by ID. */
137 private static final ConcurrentMap<String, ZoneOffset> ID_CACHE = new ConcurrentHashMap<>(16, 0.75f, 4);
138
139 /**
140 * The abs maximum seconds.
141 */
142 private static final int MAX_SECONDS = 18 * SECONDS_PER_HOUR;
143 /**
144 * Serialization version.
145 */
146 @java.io.Serial
147 private static final long serialVersionUID = 2357656521762053153L;
148
149 /**
150 * The time-zone offset for UTC, with an ID of 'Z'.
151 */
152 public static final ZoneOffset UTC = ZoneOffset.ofTotalSeconds(0);
153 /**
154 * Constant for the minimum supported offset.
155 */
156 public static final ZoneOffset MIN = ZoneOffset.ofTotalSeconds(-MAX_SECONDS);
157 /**
158 * Constant for the maximum supported offset.
159 */
160 public static final ZoneOffset MAX = ZoneOffset.ofTotalSeconds(MAX_SECONDS);
161
162 /**
163 * The total offset in seconds.
164 */
165 private final int totalSeconds;
166 /**
167 * The string form of the time-zone offset.
168 */
169 private final transient String id;
170
171 //-----------------------------------------------------------------------
172 /**
173 * Obtains an instance of {@code ZoneOffset} using the ID.
174 * <p>
175 * This method parses the string ID of a {@code ZoneOffset} to
176 * return an instance. The parsing accepts all the formats generated by
177 * {@link #getId()}, plus some additional formats:
178 * <ul>
179 * <li>{@code Z} - for UTC
180 * <li>{@code +h}
181 * <li>{@code +hh}
182 * <li>{@code +hh:mm}
183 * <li>{@code -hh:mm}
184 * <li>{@code +hhmm}
185 * <li>{@code -hhmm}
186 * <li>{@code +hh:mm:ss}
187 * <li>{@code -hh:mm:ss}
188 * <li>{@code +hhmmss}
189 * <li>{@code -hhmmss}
190 * </ul>
191 * Note that ± means either the plus or minus symbol.
192 * <p>
193 * The ID of the returned offset will be normalized to one of the formats
194 * described by {@link #getId()}.
195 * <p>
196 * The maximum supported range is from +18:00 to -18:00 inclusive.
197 *
198 * @param offsetId the offset ID, not null
199 * @return the zone-offset, not null
200 * @throws DateTimeException if the offset ID is invalid
201 */
202 @SuppressWarnings("fallthrough")
203 public static ZoneOffset of(String offsetId) {
204 Objects.requireNonNull(offsetId, "offsetId");
205 // "Z" is always in the cache
206 ZoneOffset offset = ID_CACHE.get(offsetId);
207 if (offset != null) {
208 return offset;
209 }
210
211 // parse - +h, +hh, +hhmm, +hh:mm, +hhmmss, +hh:mm:ss
212 final int hours, minutes, seconds;
213 switch (offsetId.length()) {
214 case 2:
215 offsetId = offsetId.charAt(0) + "0" + offsetId.charAt(1); // fallthru
216 case 3:
217 hours = parseNumber(offsetId, 1, false);
218 minutes = 0;
219 seconds = 0;
220 break;
221 case 5:
222 hours = parseNumber(offsetId, 1, false);
223 minutes = parseNumber(offsetId, 3, false);
224 seconds = 0;
225 break;
226 case 6:
227 hours = parseNumber(offsetId, 1, false);
228 minutes = parseNumber(offsetId, 4, true);
229 seconds = 0;
230 break;
231 case 7:
232 hours = parseNumber(offsetId, 1, false);
233 minutes = parseNumber(offsetId, 3, false);
234 seconds = parseNumber(offsetId, 5, false);
235 break;
236 case 9:
237 hours = parseNumber(offsetId, 1, false);
238 minutes = parseNumber(offsetId, 4, true);
239 seconds = parseNumber(offsetId, 7, true);
240 break;
241 default:
242 throw new DateTimeException("Invalid ID for ZoneOffset, invalid format: " + offsetId);
243 }
244 char first = offsetId.charAt(0);
245 if (first != '+' && first != '-') {
246 throw new DateTimeException("Invalid ID for ZoneOffset, plus/minus not found when expected: " + offsetId);
247 }
248 if (first == '-') {
249 return ofHoursMinutesSeconds(-hours, -minutes, -seconds);
250 } else {
251 return ofHoursMinutesSeconds(hours, minutes, seconds);
252 }
253 }
254
255 /**
256 * Parse a two digit zero-prefixed number.
257 *
258 * @param offsetId the offset ID, not null
259 * @param pos the position to parse, valid
260 * @param precededByColon should this number be prefixed by a precededByColon
261 * @return the parsed number, from 0 to 99
262 */
263 private static int parseNumber(CharSequence offsetId, int pos, boolean precededByColon) {
264 if (precededByColon && offsetId.charAt(pos - 1) != ':') {
265 throw new DateTimeException("Invalid ID for ZoneOffset, colon not found when expected: " + offsetId);
266 }
267 char ch1 = offsetId.charAt(pos);
268 char ch2 = offsetId.charAt(pos + 1);
269 if (ch1 < '0' || ch1 > '9' || ch2 < '0' || ch2 > '9') {
270 throw new DateTimeException("Invalid ID for ZoneOffset, non numeric characters found: " + offsetId);
271 }
272 return (ch1 - 48) * 10 + (ch2 - 48);
273 }
274
275 //-----------------------------------------------------------------------
276 /**
277 * Obtains an instance of {@code ZoneOffset} using an offset in hours.
278 *
279 * @param hours the time-zone offset in hours, from -18 to +18
280 * @return the zone-offset, not null
281 * @throws DateTimeException if the offset is not in the required range
282 */
283 public static ZoneOffset ofHours(int hours) {
284 return ofHoursMinutesSeconds(hours, 0, 0);
285 }
286
287 /**
288 * Obtains an instance of {@code ZoneOffset} using an offset in
289 * hours and minutes.
290 * <p>
291 * The sign of the hours and minutes components must match.
292 * Thus, if the hours is negative, the minutes must be negative or zero.
293 * If the hours is zero, the minutes may be positive, negative or zero.
294 *
295 * @param hours the time-zone offset in hours, from -18 to +18
296 * @param minutes the time-zone offset in minutes, from 0 to ±59, sign matches hours
297 * @return the zone-offset, not null
298 * @throws DateTimeException if the offset is not in the required range
299 */
300 public static ZoneOffset ofHoursMinutes(int hours, int minutes) {
301 return ofHoursMinutesSeconds(hours, minutes, 0);
302 }
303
304 /**
305 * Obtains an instance of {@code ZoneOffset} using an offset in
306 * hours, minutes and seconds.
307 * <p>
308 * The sign of the hours, minutes and seconds components must match.
309 * Thus, if the hours is negative, the minutes and seconds must be negative or zero.
310 *
311 * @param hours the time-zone offset in hours, from -18 to +18
312 * @param minutes the time-zone offset in minutes, from 0 to ±59, sign matches hours and seconds
313 * @param seconds the time-zone offset in seconds, from 0 to ±59, sign matches hours and minutes
314 * @return the zone-offset, not null
315 * @throws DateTimeException if the offset is not in the required range
316 */
317 public static ZoneOffset ofHoursMinutesSeconds(int hours, int minutes, int seconds) {
318 validate(hours, minutes, seconds);
319 int totalSeconds = totalSeconds(hours, minutes, seconds);
320 return ofTotalSeconds(totalSeconds);
321 }
322
323 //-----------------------------------------------------------------------
324 /**
325 * Obtains an instance of {@code ZoneOffset} from a temporal object.
326 * <p>
327 * This obtains an offset based on the specified temporal.
328 * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
329 * which this factory converts to an instance of {@code ZoneOffset}.
330 * <p>
331 * A {@code TemporalAccessor} represents some form of date and time information.
332 * This factory converts the arbitrary temporal object to an instance of {@code ZoneOffset}.
333 * <p>
334 * The conversion uses the {@link TemporalQueries#offset()} query, which relies
335 * on extracting the {@link ChronoField#OFFSET_SECONDS OFFSET_SECONDS} field.
336 * <p>
337 * This method matches the signature of the functional interface {@link TemporalQuery}
338 * allowing it to be used as a query via method reference, {@code ZoneOffset::from}.
339 *
340 * @param temporal the temporal object to convert, not null
341 * @return the zone-offset, not null
342 * @throws DateTimeException if unable to convert to an {@code ZoneOffset}
343 */
344 public static ZoneOffset from(TemporalAccessor temporal) {
345 Objects.requireNonNull(temporal, "temporal");
346 ZoneOffset offset = temporal.query(TemporalQueries.offset());
347 if (offset == null) {
348 throw new DateTimeException("Unable to obtain ZoneOffset from TemporalAccessor: " +
349 temporal + " of type " + temporal.getClass().getName());
350 }
351 return offset;
352 }
353
354 //-----------------------------------------------------------------------
355 /**
356 * Validates the offset fields.
357 *
358 * @param hours the time-zone offset in hours, from -18 to +18
359 * @param minutes the time-zone offset in minutes, from 0 to ±59
360 * @param seconds the time-zone offset in seconds, from 0 to ±59
361 * @throws DateTimeException if the offset is not in the required range
362 */
363 private static void validate(int hours, int minutes, int seconds) {
364 if (hours < -18 || hours > 18) {
365 throw new DateTimeException("Zone offset hours not in valid range: value " + hours +
366 " is not in the range -18 to 18");
367 }
368 if (hours > 0) {
369 if (minutes < 0 || seconds < 0) {
370 throw new DateTimeException("Zone offset minutes and seconds must be positive because hours is positive");
371 }
372 } else if (hours < 0) {
373 if (minutes > 0 || seconds > 0) {
374 throw new DateTimeException("Zone offset minutes and seconds must be negative because hours is negative");
375 }
376 } else if ((minutes > 0 && seconds < 0) || (minutes < 0 && seconds > 0)) {
377 throw new DateTimeException("Zone offset minutes and seconds must have the same sign");
378 }
379 if (minutes < -59 || minutes > 59) {
380 throw new DateTimeException("Zone offset minutes not in valid range: value " +
381 minutes + " is not in the range -59 to 59");
382 }
383 if (seconds < -59 || seconds > 59) {
384 throw new DateTimeException("Zone offset seconds not in valid range: value " +
385 seconds + " is not in the range -59 to 59");
386 }
387 if (Math.abs(hours) == 18 && (minutes | seconds) != 0) {
388 throw new DateTimeException("Zone offset not in valid range: -18:00 to +18:00");
389 }
390 }
391
392 /**
393 * Calculates the total offset in seconds.
394 *
395 * @param hours the time-zone offset in hours, from -18 to +18
396 * @param minutes the time-zone offset in minutes, from 0 to ±59, sign matches hours and seconds
397 * @param seconds the time-zone offset in seconds, from 0 to ±59, sign matches hours and minutes
398 * @return the total in seconds
399 */
400 private static int totalSeconds(int hours, int minutes, int seconds) {
401 return hours * SECONDS_PER_HOUR + minutes * SECONDS_PER_MINUTE + seconds;
402 }
403
404 //-----------------------------------------------------------------------
405 /**
406 * Obtains an instance of {@code ZoneOffset} specifying the total offset in seconds
407 * <p>
408 * The offset must be in the range {@code -18:00} to {@code +18:00}, which corresponds to -64800 to +64800.
409 *
410 * @param totalSeconds the total time-zone offset in seconds, from -64800 to +64800
411 * @return the ZoneOffset, not null
412 * @throws DateTimeException if the offset is not in the required range
413 */
414 public static ZoneOffset ofTotalSeconds(int totalSeconds) {
415 if (totalSeconds < -MAX_SECONDS || totalSeconds > MAX_SECONDS) {
416 throw new DateTimeException("Zone offset not in valid range: -18:00 to +18:00");
417 }
418 if (totalSeconds % (15 * SECONDS_PER_MINUTE) == 0) {
419 Integer totalSecs = totalSeconds;
420 ZoneOffset result = SECONDS_CACHE.get(totalSecs);
421 if (result == null) {
422 result = new ZoneOffset(totalSeconds);
423 SECONDS_CACHE.putIfAbsent(totalSecs, result);
424 result = SECONDS_CACHE.get(totalSecs);
425 ID_CACHE.putIfAbsent(result.getId(), result);
426 }
427 return result;
428 } else {
429 return new ZoneOffset(totalSeconds);
430 }
431 }
432
433 //-----------------------------------------------------------------------
434 /**
435 * Constructor.
436 *
437 * @param totalSeconds the total time-zone offset in seconds, from -64800 to +64800
438 */
439 private ZoneOffset(int totalSeconds) {
440 super();
441 this.totalSeconds = totalSeconds;
442 id = buildId(totalSeconds);
443 }
444
445 private static String buildId(int totalSeconds) {
446 if (totalSeconds == 0) {
447 return "Z";
448 } else {
449 int absTotalSeconds = Math.abs(totalSeconds);
450 StringBuilder buf = new StringBuilder();
451 int absHours = absTotalSeconds / SECONDS_PER_HOUR;
452 int absMinutes = (absTotalSeconds / SECONDS_PER_MINUTE) % MINUTES_PER_HOUR;
453 buf.append(totalSeconds < 0 ? "-" : "+")
454 .append(absHours < 10 ? "0" : "").append(absHours)
455 .append(absMinutes < 10 ? ":0" : ":").append(absMinutes);
456 int absSeconds = absTotalSeconds % SECONDS_PER_MINUTE;
457 if (absSeconds != 0) {
458 buf.append(absSeconds < 10 ? ":0" : ":").append(absSeconds);
459 }
460 return buf.toString();
461 }
462 }
463
464 //-----------------------------------------------------------------------
465 /**
466 * Gets the total zone offset in seconds.
467 * <p>
468 * This is the primary way to access the offset amount.
469 * It returns the total of the hours, minutes and seconds fields as a
470 * single offset that can be added to a time.
471 *
472 * @return the total zone offset amount in seconds
473 */
474 public int getTotalSeconds() {
475 return totalSeconds;
476 }
477
478 /**
479 * Gets the normalized zone offset ID.
480 * <p>
481 * The ID is minor variation to the standard ISO-8601 formatted string
482 * for the offset. There are three formats:
483 * <ul>
484 * <li>{@code Z} - for UTC (ISO-8601)
485 * <li>{@code +hh:mm} or {@code -hh:mm} - if the seconds are zero (ISO-8601)
486 * <li>{@code +hh:mm:ss} or {@code -hh:mm:ss} - if the seconds are non-zero (not ISO-8601)
487 * </ul>
488 *
489 * @return the zone offset ID, not null
490 */
491 @Override
492 public String getId() {
493 return id;
494 }
495
496 /**
497 * Gets the associated time-zone rules.
498 * <p>
499 * The rules will always return this offset when queried.
500 * The implementation class is immutable, thread-safe and serializable.
501 *
502 * @return the rules, not null
503 */
504 @Override
505 public ZoneRules getRules() {
506 return ZoneRules.of(this);
507 }
508
509 //-----------------------------------------------------------------------
510 /**
511 * Checks if the specified field is supported.
512 * <p>
513 * This checks if this offset can be queried for the specified field.
514 * If false, then calling the {@link #range(TemporalField) range} and
515 * {@link #get(TemporalField) get} methods will throw an exception.
516 * <p>
517 * If the field is a {@link ChronoField} then the query is implemented here.
518 * The {@code OFFSET_SECONDS} field returns true.
519 * All other {@code ChronoField} instances will return false.
520 * <p>
521 * If the field is not a {@code ChronoField}, then the result of this method
522 * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
523 * passing {@code this} as the argument.
524 * Whether the field is supported is determined by the field.
525 *
526 * @param field the field to check, null returns false
527 * @return true if the field is supported on this offset, false if not
528 */
529 @Override
530 public boolean isSupported(TemporalField field) {
531 if (field instanceof ChronoField) {
532 return field == OFFSET_SECONDS;
533 }
534 return field != null && field.isSupportedBy(this);
535 }
536
537 /**
538 * Gets the range of valid values for the specified field.
539 * <p>
540 * The range object expresses the minimum and maximum valid values for a field.
541 * This offset is used to enhance the accuracy of the returned range.
542 * If it is not possible to return the range, because the field is not supported
543 * or for some other reason, an exception is thrown.
544 * <p>
545 * If the field is a {@link ChronoField} then the query is implemented here.
546 * The {@link #isSupported(TemporalField) supported fields} will return
547 * appropriate range instances.
548 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
549 * <p>
550 * If the field is not a {@code ChronoField}, then the result of this method
551 * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
552 * passing {@code this} as the argument.
553 * Whether the range can be obtained is determined by the field.
554 *
555 * @param field the field to query the range for, not null
556 * @return the range of valid values for the field, not null
557 * @throws DateTimeException if the range for the field cannot be obtained
558 * @throws UnsupportedTemporalTypeException if the field is not supported
559 */
560 @Override // override for Javadoc
561 public ValueRange range(TemporalField field) {
562 return TemporalAccessor.super.range(field);
563 }
564
565 /**
566 * Gets the value of the specified field from this offset as an {@code int}.
567 * <p>
568 * This queries this offset for the value of the specified field.
569 * The returned value will always be within the valid range of values for the field.
570 * If it is not possible to return the value, because the field is not supported
571 * or for some other reason, an exception is thrown.
572 * <p>
573 * If the field is a {@link ChronoField} then the query is implemented here.
574 * The {@code OFFSET_SECONDS} field returns the value of the offset.
575 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
576 * <p>
577 * If the field is not a {@code ChronoField}, then the result of this method
578 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
579 * passing {@code this} as the argument. Whether the value can be obtained,
580 * and what the value represents, is determined by the field.
581 *
582 * @param field the field to get, not null
583 * @return the value for the field
584 * @throws DateTimeException if a value for the field cannot be obtained or
585 * the value is outside the range of valid values for the field
586 * @throws UnsupportedTemporalTypeException if the field is not supported or
587 * the range of values exceeds an {@code int}
588 * @throws ArithmeticException if numeric overflow occurs
589 */
590 @Override // override for Javadoc and performance
591 public int get(TemporalField field) {
592 if (field == OFFSET_SECONDS) {
593 return totalSeconds;
594 } else if (field instanceof ChronoField) {
595 throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
596 }
597 return range(field).checkValidIntValue(getLong(field), field);
598 }
599
600 /**
601 * Gets the value of the specified field from this offset as a {@code long}.
602 * <p>
603 * This queries this offset for the value of the specified field.
604 * If it is not possible to return the value, because the field is not supported
605 * or for some other reason, an exception is thrown.
606 * <p>
607 * If the field is a {@link ChronoField} then the query is implemented here.
608 * The {@code OFFSET_SECONDS} field returns the value of the offset.
609 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
610 * <p>
611 * If the field is not a {@code ChronoField}, then the result of this method
612 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
613 * passing {@code this} as the argument. Whether the value can be obtained,
614 * and what the value represents, is determined by the field.
615 *
616 * @param field the field to get, not null
617 * @return the value for the field
618 * @throws DateTimeException if a value for the field cannot be obtained
619 * @throws UnsupportedTemporalTypeException if the field is not supported
620 * @throws ArithmeticException if numeric overflow occurs
621 */
622 @Override
623 public long getLong(TemporalField field) {
624 if (field == OFFSET_SECONDS) {
625 return totalSeconds;
626 } else if (field instanceof ChronoField) {
627 throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
628 }
629 return field.getFrom(this);
630 }
631
632 //-----------------------------------------------------------------------
633 /**
634 * Queries this offset using the specified query.
635 * <p>
636 * This queries this offset using the specified query strategy object.
637 * The {@code TemporalQuery} object defines the logic to be used to
638 * obtain the result. Read the documentation of the query to understand
639 * what the result of this method will be.
640 * <p>
641 * The result of this method is obtained by invoking the
642 * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
643 * specified query passing {@code this} as the argument.
644 *
645 * @param <R> the type of the result
646 * @param query the query to invoke, not null
647 * @return the query result, null may be returned (defined by the query)
648 * @throws DateTimeException if unable to query (defined by the query)
649 * @throws ArithmeticException if numeric overflow occurs (defined by the query)
650 */
651 @SuppressWarnings("unchecked")
652 @Override
653 public <R> R query(TemporalQuery<R> query) {
654 if (query == TemporalQueries.offset() || query == TemporalQueries.zone()) {
655 return (R) this;
656 }
657 return TemporalAccessor.super.query(query);
658 }
659
660 /**
661 * Adjusts the specified temporal object to have the same offset as this object.
662 * <p>
663 * This returns a temporal object of the same observable type as the input
664 * with the offset changed to be the same as this.
665 * <p>
666 * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
667 * passing {@link ChronoField#OFFSET_SECONDS} as the field.
668 * <p>
669 * In most cases, it is clearer to reverse the calling pattern by using
670 * {@link Temporal#with(TemporalAdjuster)}:
671 * <pre>
672 * // these two lines are equivalent, but the second approach is recommended
673 * temporal = thisOffset.adjustInto(temporal);
674 * temporal = temporal.with(thisOffset);
675 * </pre>
676 * <p>
677 * This instance is immutable and unaffected by this method call.
678 *
679 * @param temporal the target object to be adjusted, not null
680 * @return the adjusted object, not null
681 * @throws DateTimeException if unable to make the adjustment
682 * @throws ArithmeticException if numeric overflow occurs
683 */
684 @Override
685 public Temporal adjustInto(Temporal temporal) {
686 return temporal.with(OFFSET_SECONDS, totalSeconds);
687 }
688
689 //-----------------------------------------------------------------------
690 /**
691 * Compares this offset to another offset in descending order.
692 * <p>
693 * The offsets are compared in the order that they occur for the same time
694 * of day around the world. Thus, an offset of {@code +10:00} comes before an
695 * offset of {@code +09:00} and so on down to {@code -18:00}.
696 * <p>
697 * The comparison is "consistent with equals", as defined by {@link Comparable}.
698 *
699 * @param other the other date to compare to, not null
700 * @return the comparator value, negative if less, positive if greater
701 * @throws NullPointerException if {@code other} is null
702 */
703 @Override
704 public int compareTo(ZoneOffset other) {
705 // abs(totalSeconds) <= MAX_SECONDS, so no overflow can happen here
706 return other.totalSeconds - totalSeconds;
707 }
708
709 //-----------------------------------------------------------------------
710 /**
711 * Checks if this offset is equal to another offset.
712 * <p>
713 * The comparison is based on the amount of the offset in seconds.
714 * This is equivalent to a comparison by ID.
715 *
716 * @param obj the object to check, null returns false
717 * @return true if this is equal to the other offset
718 */
719 @Override
720 public boolean equals(Object obj) {
721 if (this == obj) {
722 return true;
723 }
724 if (obj instanceof ZoneOffset) {
725 return totalSeconds == ((ZoneOffset) obj).totalSeconds;
726 }
727 return false;
728 }
729
730 /**
731 * A hash code for this offset.
732 *
733 * @return a suitable hash code
734 */
735 @Override
736 public int hashCode() {
737 return totalSeconds;
738 }
739
740 //-----------------------------------------------------------------------
741 /**
742 * Outputs this offset as a {@code String}, using the normalized ID.
743 *
744 * @return a string representation of this offset, not null
745 */
746 @Override
747 public String toString() {
748 return id;
749 }
750
751 // -----------------------------------------------------------------------
752 /**
753 * Writes the object using a
754 * <a href="{@docRoot}/serialized-form.html#java.time.Ser">dedicated serialized form</a>.
755 * @serialData
756 * <pre>
757 * out.writeByte(8); // identifies a ZoneOffset
758 * int offsetByte = totalSeconds % 900 == 0 ? totalSeconds / 900 : 127;
759 * out.writeByte(offsetByte);
760 * if (offsetByte == 127) {
761 * out.writeInt(totalSeconds);
762 * }
763 * </pre>
764 *
765 * @return the instance of {@code Ser}, not null
766 */
767 @java.io.Serial
768 private Object writeReplace() {
769 return new Ser(Ser.ZONE_OFFSET_TYPE, this);
770 }
771
772 /**
773 * Defend against malicious streams.
774 *
775 * @param s the stream to read
776 * @throws InvalidObjectException always
777 */
778 @java.io.Serial
779 private void readObject(ObjectInputStream s) throws InvalidObjectException {
780 throw new InvalidObjectException("Deserialization via serialization delegate");
781 }
782
783 @Override
784 void write(DataOutput out) throws IOException {
785 out.writeByte(Ser.ZONE_OFFSET_TYPE);
786 writeExternal(out);
787 }
788
789 void writeExternal(DataOutput out) throws IOException {
790 final int offsetSecs = totalSeconds;
791 int offsetByte = offsetSecs % 900 == 0 ? offsetSecs / 900 : 127; // compress to -72 to +72
792 out.writeByte(offsetByte);
793 if (offsetByte == 127) {
794 out.writeInt(offsetSecs);
795 }
796 }
797
798 static ZoneOffset readExternal(DataInput in) throws IOException {
799 int offsetByte = in.readByte();
800 return (offsetByte == 127 ? ZoneOffset.ofTotalSeconds(in.readInt()) : ZoneOffset.ofTotalSeconds(offsetByte * 900));
801 }
802
803 }