1 /*
2 * Copyright (c) 2012, 2023, 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
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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 static java.time.temporal.ChronoField.ERA;
65 import static java.time.temporal.ChronoField.YEAR;
66 import static java.time.temporal.ChronoField.YEAR_OF_ERA;
67 import static java.time.temporal.ChronoUnit.CENTURIES;
68 import static java.time.temporal.ChronoUnit.DECADES;
69 import static java.time.temporal.ChronoUnit.ERAS;
70 import static java.time.temporal.ChronoUnit.MILLENNIA;
71 import static java.time.temporal.ChronoUnit.YEARS;
72
73 import java.io.DataInput;
74 import java.io.DataOutput;
75 import java.io.IOException;
76 import java.io.InvalidObjectException;
77 import java.io.ObjectInputStream;
78 import java.io.Serializable;
79 import java.time.chrono.Chronology;
80 import java.time.chrono.IsoChronology;
81 import java.time.format.DateTimeFormatter;
82 import java.time.format.DateTimeFormatterBuilder;
83 import java.time.format.DateTimeParseException;
84 import java.time.format.SignStyle;
85 import java.time.temporal.ChronoField;
86 import java.time.temporal.ChronoUnit;
87 import java.time.temporal.Temporal;
88 import java.time.temporal.TemporalAccessor;
89 import java.time.temporal.TemporalAdjuster;
90 import java.time.temporal.TemporalAmount;
91 import java.time.temporal.TemporalField;
92 import java.time.temporal.TemporalQueries;
93 import java.time.temporal.TemporalQuery;
94 import java.time.temporal.TemporalUnit;
95 import java.time.temporal.UnsupportedTemporalTypeException;
96 import java.time.temporal.ValueRange;
97 import java.util.Objects;
98
99 /**
100 * A year in the ISO-8601 calendar system, such as {@code 2007}.
101 * <p>
102 * {@code Year} is an immutable date-time object that represents a year.
103 * Any field that can be derived from a year can be obtained.
104 * <p>
105 * <b>Note that years in the ISO chronology only align with years in the
106 * Gregorian-Julian system for modern years. Parts of Russia did not switch to the
107 * modern Gregorian/ISO rules until 1920.
108 * As such, historical years must be treated with caution.</b>
109 * <p>
110 * This class does not store or represent a month, day, time or time-zone.
111 * For example, the value "2007" can be stored in a {@code Year}.
112 * <p>
113 * Years represented by this class follow the ISO-8601 standard and use
114 * the proleptic numbering system. Year 1 is preceded by year 0, then by year -1.
115 * <p>
116 * The ISO-8601 calendar system is the modern civil calendar system used today
117 * in most of the world. It is equivalent to the proleptic Gregorian calendar
118 * system, in which today's rules for leap years are applied for all time.
119 * For most applications written today, the ISO-8601 rules are entirely suitable.
120 * However, any application that makes use of historical dates, and requires them
121 * to be accurate will find the ISO-8601 approach unsuitable.
122 * <p>
123 * This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
124 * class; programmers should treat instances that are {@linkplain #equals(Object) equal}
125 * as interchangeable and should not use instances for synchronization, mutexes, or
126 * with {@linkplain java.lang.ref.Reference object references}.
127 *
128 * <div class="preview-block">
129 * <div class="preview-comment">
130 * When preview features are enabled, {@code Year} is a {@linkplain Class#isValue value class}.
131 * Use of value class instances for synchronization, mutexes, or with
132 * {@linkplain java.lang.ref.Reference object references} result in
133 * {@link IdentityException}.
134 * </div>
135 * </div>
136 *
137 * @implSpec
138 * This class is immutable and thread-safe.
139 *
140 * @since 1.8
141 */
142 @jdk.internal.ValueBased
143 @jdk.internal.MigratedValueClass
144 public final class Year
145 implements Temporal, TemporalAdjuster, Comparable<Year>, Serializable {
146
147 /**
148 * The minimum supported year, '-999,999,999'.
149 */
150 public static final int MIN_VALUE = -999_999_999;
151 /**
152 * The maximum supported year, '+999,999,999'.
153 */
154 public static final int MAX_VALUE = 999_999_999;
155
156 /**
157 * Serialization version.
158 */
159 @java.io.Serial
160 private static final long serialVersionUID = -23038383694477807L;
161 /**
162 * Parser.
163 */
164 private static final DateTimeFormatter PARSER = new DateTimeFormatterBuilder()
165 .parseLenient()
166 .appendValue(YEAR, 1, 10, SignStyle.NORMAL)
167 .toFormatter();
168
169 /**
170 * The year being represented.
171 */
172 private final int year;
173
174 //-----------------------------------------------------------------------
175 /**
176 * Obtains the current year from the system clock in the default time-zone.
177 * <p>
178 * This will query the {@link Clock#systemDefaultZone() system clock} in the default
179 * time-zone to obtain the current year.
180 * <p>
181 * Using this method will prevent the ability to use an alternate clock for testing
182 * because the clock is hard-coded.
183 *
184 * @return the current year using the system clock and default time-zone, not null
185 */
186 public static Year now() {
187 return now(Clock.systemDefaultZone());
188 }
189
190 /**
191 * Obtains the current year from the system clock in the specified time-zone.
192 * <p>
193 * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current year.
194 * Specifying the time-zone avoids dependence on the default time-zone.
195 * <p>
196 * Using this method will prevent the ability to use an alternate clock for testing
197 * because the clock is hard-coded.
198 *
199 * @param zone the zone ID to use, not null
200 * @return the current year using the system clock, not null
201 */
202 public static Year now(ZoneId zone) {
203 return now(Clock.system(zone));
204 }
205
206 /**
207 * Obtains the current year from the specified clock.
208 * <p>
209 * This will query the specified clock to obtain the current year.
210 * Using this method allows the use of an alternate clock for testing.
211 * The alternate clock may be introduced using {@link Clock dependency injection}.
212 *
213 * @param clock the clock to use, not null
214 * @return the current year, not null
215 */
216 public static Year now(Clock clock) {
217 final LocalDate now = LocalDate.now(clock); // called once
218 return Year.of(now.getYear());
219 }
220
221 //-----------------------------------------------------------------------
222 /**
223 * Obtains an instance of {@code Year}.
224 * <p>
225 * This method accepts a year value from the proleptic ISO calendar system.
226 * <p>
227 * The year 2AD/CE is represented by 2.<br>
228 * The year 1AD/CE is represented by 1.<br>
229 * The year 1BC/BCE is represented by 0.<br>
230 * The year 2BC/BCE is represented by -1.<br>
231 *
232 * @param isoYear the ISO proleptic year to represent, from {@code MIN_VALUE} to {@code MAX_VALUE}
233 * @return the year, not null
234 * @throws DateTimeException if the field is invalid
235 */
236 public static Year of(int isoYear) {
237 YEAR.checkValidValue(isoYear);
238 return new Year(isoYear);
239 }
240
241 //-----------------------------------------------------------------------
242 /**
243 * Obtains an instance of {@code Year} from a temporal object.
244 * <p>
245 * This obtains a year based on the specified temporal.
246 * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
247 * which this factory converts to an instance of {@code Year}.
248 * <p>
249 * The conversion extracts the {@link ChronoField#YEAR year} field.
250 * The extraction is only permitted if the temporal object has an ISO
251 * chronology, or can be converted to a {@code LocalDate}.
252 * <p>
253 * This method matches the signature of the functional interface {@link TemporalQuery}
254 * allowing it to be used as a query via method reference, {@code Year::from}.
255 *
256 * @param temporal the temporal object to convert, not null
257 * @return the year, not null
258 * @throws DateTimeException if unable to convert to a {@code Year}
259 */
260 public static Year from(TemporalAccessor temporal) {
261 if (temporal instanceof Year) {
262 return (Year) temporal;
263 }
264 Objects.requireNonNull(temporal, "temporal");
265 try {
266 if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) {
267 temporal = LocalDate.from(temporal);
268 }
269 return of(temporal.get(YEAR));
270 } catch (DateTimeException ex) {
271 throw new DateTimeException("Unable to obtain Year from TemporalAccessor: " +
272 temporal + " of type " + temporal.getClass().getName(), ex);
273 }
274 }
275
276 //-----------------------------------------------------------------------
277 /**
278 * Obtains an instance of {@code Year} from a text string such as {@code 2007}.
279 * <p>
280 * The string must represent a valid year.
281 *
282 * @param text the text to parse such as "2007", not null
283 * @return the parsed year, not null
284 * @throws DateTimeParseException if the text cannot be parsed
285 */
286 public static Year parse(CharSequence text) {
287 return parse(text, PARSER);
288 }
289
290 /**
291 * Obtains an instance of {@code Year} from a text string using a specific formatter.
292 * <p>
293 * The text is parsed using the formatter, returning a year.
294 *
295 * @param text the text to parse, not null
296 * @param formatter the formatter to use, not null
297 * @return the parsed year, not null
298 * @throws DateTimeParseException if the text cannot be parsed
299 */
300 public static Year parse(CharSequence text, DateTimeFormatter formatter) {
301 Objects.requireNonNull(formatter, "formatter");
302 return formatter.parse(text, Year::from);
303 }
304
305 //-------------------------------------------------------------------------
306 /**
307 * Checks if the year is a leap year, according to the ISO proleptic
308 * calendar system rules.
309 * <p>
310 * This method applies the current rules for leap years across the whole time-line.
311 * In general, a year is a leap year if it is divisible by four without
312 * remainder. However, years divisible by 100, are not leap years, with
313 * the exception of years divisible by 400 which are.
314 * <p>
315 * For example, 1904 is a leap year it is divisible by 4.
316 * 1900 was not a leap year as it is divisible by 100, however 2000 was a
317 * leap year as it is divisible by 400.
318 * <p>
319 * The calculation is proleptic - applying the same rules into the far future and far past.
320 * This is historically inaccurate, but is correct for the ISO-8601 standard.
321 *
322 * @param year the year to check
323 * @return true if the year is leap, false otherwise
324 */
325 public static boolean isLeap(long year) {
326 // A year that is a multiple of 100, 200 and 300 is not divisible by 16, but 400 is.
327 // So for a year that's divisible by 4, checking that it's also divisible by 16
328 // is sufficient to determine it must be a leap year.
329 return (year & 15) == 0 ? (year & 3) == 0 : (year & 3) == 0 && year % 100 != 0;
330 }
331
332 //-----------------------------------------------------------------------
333 /**
334 * Constructor.
335 *
336 * @param year the year to represent
337 */
338 private Year(int year) {
339 this.year = year;
340 }
341
342 //-----------------------------------------------------------------------
343 /**
344 * Gets the year value.
345 * <p>
346 * The year returned by this method is proleptic as per {@code get(YEAR)}.
347 *
348 * @return the year, {@code MIN_VALUE} to {@code MAX_VALUE}
349 */
350 public int getValue() {
351 return year;
352 }
353
354 //-----------------------------------------------------------------------
355 /**
356 * Checks if the specified field is supported.
357 * <p>
358 * This checks if this year can be queried for the specified field.
359 * If false, then calling the {@link #range(TemporalField) range},
360 * {@link #get(TemporalField) get} and {@link #with(TemporalField, long)}
361 * methods will throw an exception.
362 * <p>
363 * If the field is a {@link ChronoField} then the query is implemented here.
364 * The supported fields are:
365 * <ul>
366 * <li>{@code YEAR_OF_ERA}
367 * <li>{@code YEAR}
368 * <li>{@code ERA}
369 * </ul>
370 * All other {@code ChronoField} instances will return false.
371 * <p>
372 * If the field is not a {@code ChronoField}, then the result of this method
373 * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
374 * passing {@code this} as the argument.
375 * Whether the field is supported is determined by the field.
376 *
377 * @param field the field to check, null returns false
378 * @return true if the field is supported on this year, false if not
379 */
380 @Override
381 public boolean isSupported(TemporalField field) {
382 if (field instanceof ChronoField) {
383 return field == YEAR || field == YEAR_OF_ERA || field == ERA;
384 }
385 return field != null && field.isSupportedBy(this);
386 }
387
388 /**
389 * Checks if the specified unit is supported.
390 * <p>
391 * This checks if the specified unit can be added to, or subtracted from, this year.
392 * If false, then calling the {@link #plus(long, TemporalUnit)} and
393 * {@link #minus(long, TemporalUnit) minus} methods will throw an exception.
394 * <p>
395 * If the unit is a {@link ChronoUnit} then the query is implemented here.
396 * The supported units are:
397 * <ul>
398 * <li>{@code YEARS}
399 * <li>{@code DECADES}
400 * <li>{@code CENTURIES}
401 * <li>{@code MILLENNIA}
402 * <li>{@code ERAS}
403 * </ul>
404 * All other {@code ChronoUnit} instances will return false.
405 * <p>
406 * If the unit is not a {@code ChronoUnit}, then the result of this method
407 * is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}
408 * passing {@code this} as the argument.
409 * Whether the unit is supported is determined by the unit.
410 *
411 * @param unit the unit to check, null returns false
412 * @return true if the unit can be added/subtracted, false if not
413 */
414 @Override
415 public boolean isSupported(TemporalUnit unit) {
416 if (unit instanceof ChronoUnit) {
417 return unit == YEARS || unit == DECADES || unit == CENTURIES || unit == MILLENNIA || unit == ERAS;
418 }
419 return unit != null && unit.isSupportedBy(this);
420 }
421
422 //-----------------------------------------------------------------------
423 /**
424 * Gets the range of valid values for the specified field.
425 * <p>
426 * The range object expresses the minimum and maximum valid values for a field.
427 * This year is used to enhance the accuracy of the returned range.
428 * If it is not possible to return the range, because the field is not supported
429 * or for some other reason, an exception is thrown.
430 * <p>
431 * If the field is a {@link ChronoField} then the query is implemented here.
432 * The {@link #isSupported(TemporalField) supported fields} will return
433 * appropriate range instances.
434 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
435 * <p>
436 * If the field is not a {@code ChronoField}, then the result of this method
437 * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
438 * passing {@code this} as the argument.
439 * Whether the range can be obtained is determined by the field.
440 *
441 * @param field the field to query the range for, not null
442 * @return the range of valid values for the field, not null
443 * @throws DateTimeException if the range for the field cannot be obtained
444 * @throws UnsupportedTemporalTypeException if the field is not supported
445 */
446 @Override
447 public ValueRange range(TemporalField field) {
448 if (field == YEAR_OF_ERA) {
449 return (year <= 0 ? ValueRange.of(1, MAX_VALUE + 1) : ValueRange.of(1, MAX_VALUE));
450 }
451 return Temporal.super.range(field);
452 }
453
454 /**
455 * Gets the value of the specified field from this year as an {@code int}.
456 * <p>
457 * This queries this year for the value of the specified field.
458 * The returned value will always be within the valid range of values for the field.
459 * If it is not possible to return the value, because the field is not supported
460 * or for some other reason, an exception is thrown.
461 * <p>
462 * If the field is a {@link ChronoField} then the query is implemented here.
463 * The {@link #isSupported(TemporalField) supported fields} will return valid
464 * values based on this year.
465 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
466 * <p>
467 * If the field is not a {@code ChronoField}, then the result of this method
468 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
469 * passing {@code this} as the argument. Whether the value can be obtained,
470 * and what the value represents, is determined by the field.
471 *
472 * @param field the field to get, not null
473 * @return the value for the field
474 * @throws DateTimeException if a value for the field cannot be obtained or
475 * the value is outside the range of valid values for the field
476 * @throws UnsupportedTemporalTypeException if the field is not supported or
477 * the range of values exceeds an {@code int}
478 * @throws ArithmeticException if numeric overflow occurs
479 */
480 @Override // override for Javadoc
481 public int get(TemporalField field) {
482 return range(field).checkValidIntValue(getLong(field), field);
483 }
484
485 /**
486 * Gets the value of the specified field from this year as a {@code long}.
487 * <p>
488 * This queries this year for the value of the specified field.
489 * If it is not possible to return the value, because the field is not supported
490 * or for some other reason, an exception is thrown.
491 * <p>
492 * If the field is a {@link ChronoField} then the query is implemented here.
493 * The {@link #isSupported(TemporalField) supported fields} will return valid
494 * values based on this year.
495 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
496 * <p>
497 * If the field is not a {@code ChronoField}, then the result of this method
498 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
499 * passing {@code this} as the argument. Whether the value can be obtained,
500 * and what the value represents, is determined by the field.
501 *
502 * @param field the field to get, not null
503 * @return the value for the field
504 * @throws DateTimeException if a value for the field cannot be obtained
505 * @throws UnsupportedTemporalTypeException if the field is not supported
506 * @throws ArithmeticException if numeric overflow occurs
507 */
508 @Override
509 public long getLong(TemporalField field) {
510 if (field instanceof ChronoField chronoField) {
511 return switch (chronoField) {
512 case YEAR_OF_ERA -> year < 1 ? 1 - year : year;
513 case YEAR -> year;
514 case ERA -> year < 1 ? 0 : 1;
515 default -> throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
516 };
517 }
518 return field.getFrom(this);
519 }
520
521 //-----------------------------------------------------------------------
522 /**
523 * Checks if the year is a leap year, according to the ISO proleptic
524 * calendar system rules.
525 * <p>
526 * This method applies the current rules for leap years across the whole time-line.
527 * In general, a year is a leap year if it is divisible by four without
528 * remainder. However, years divisible by 100, are not leap years, with
529 * the exception of years divisible by 400 which are.
530 * <p>
531 * For example, 1904 is a leap year it is divisible by 4.
532 * 1900 was not a leap year as it is divisible by 100, however 2000 was a
533 * leap year as it is divisible by 400.
534 * <p>
535 * The calculation is proleptic - applying the same rules into the far future and far past.
536 * This is historically inaccurate, but is correct for the ISO-8601 standard.
537 *
538 * @return true if the year is leap, false otherwise
539 */
540 public boolean isLeap() {
541 return Year.isLeap(year);
542 }
543
544 /**
545 * Checks if the month-day is valid for this year.
546 * <p>
547 * This method checks whether this year and the input month and day form
548 * a valid date.
549 *
550 * @param monthDay the month-day to validate, null returns false
551 * @return true if the month and day are valid for this year
552 */
553 public boolean isValidMonthDay(MonthDay monthDay) {
554 return monthDay != null && monthDay.isValidYear(year);
555 }
556
557 /**
558 * Gets the length of this year in days.
559 *
560 * @return the length of this year in days, 365 or 366
561 */
562 public int length() {
563 return isLeap() ? 366 : 365;
564 }
565
566 //-----------------------------------------------------------------------
567 /**
568 * Returns an adjusted copy of this year.
569 * <p>
570 * This returns a {@code Year}, based on this one, with the year adjusted.
571 * The adjustment takes place using the specified adjuster strategy object.
572 * Read the documentation of the adjuster to understand what adjustment will be made.
573 * <p>
574 * The result of this method is obtained by invoking the
575 * {@link TemporalAdjuster#adjustInto(Temporal)} method on the
576 * specified adjuster passing {@code this} as the argument.
577 * <p>
578 * This instance is immutable and unaffected by this method call.
579 *
580 * @param adjuster the adjuster to use, not null
581 * @return a {@code Year} based on {@code this} with the adjustment made, not null
582 * @throws DateTimeException if the adjustment cannot be made
583 * @throws ArithmeticException if numeric overflow occurs
584 */
585 @Override
586 public Year with(TemporalAdjuster adjuster) {
587 return (Year) adjuster.adjustInto(this);
588 }
589
590 /**
591 * Returns a copy of this year with the specified field set to a new value.
592 * <p>
593 * This returns a {@code Year}, based on this one, with the value
594 * for the specified field changed.
595 * If it is not possible to set the value, because the field is not supported or for
596 * some other reason, an exception is thrown.
597 * <p>
598 * If the field is a {@link ChronoField} then the adjustment is implemented here.
599 * The supported fields behave as follows:
600 * <ul>
601 * <li>{@code YEAR_OF_ERA} -
602 * Returns a {@code Year} with the specified year-of-era
603 * The era will be unchanged.
604 * <li>{@code YEAR} -
605 * Returns a {@code Year} with the specified year.
606 * This completely replaces the date and is equivalent to {@link #of(int)}.
607 * <li>{@code ERA} -
608 * Returns a {@code Year} with the specified era.
609 * The year-of-era will be unchanged.
610 * </ul>
611 * <p>
612 * In all cases, if the new value is outside the valid range of values for the field
613 * then a {@code DateTimeException} will be thrown.
614 * <p>
615 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
616 * <p>
617 * If the field is not a {@code ChronoField}, then the result of this method
618 * is obtained by invoking {@code TemporalField.adjustInto(Temporal, long)}
619 * passing {@code this} as the argument. In this case, the field determines
620 * whether and how to adjust the instant.
621 * <p>
622 * This instance is immutable and unaffected by this method call.
623 *
624 * @param field the field to set in the result, not null
625 * @param newValue the new value of the field in the result
626 * @return a {@code Year} based on {@code this} with the specified field set, not null
627 * @throws DateTimeException if the field cannot be set
628 * @throws UnsupportedTemporalTypeException if the field is not supported
629 * @throws ArithmeticException if numeric overflow occurs
630 */
631 @Override
632 public Year with(TemporalField field, long newValue) {
633 if (field instanceof ChronoField chronoField) {
634 chronoField.checkValidValue(newValue);
635 return switch (chronoField) {
636 case YEAR_OF_ERA -> Year.of((int) (year < 1 ? 1 - newValue : newValue));
637 case YEAR -> Year.of((int) newValue);
638 case ERA -> getLong(ERA) == newValue ? this : Year.of(1 - year);
639 default -> throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
640 };
641 }
642 return field.adjustInto(this, newValue);
643 }
644
645 //-----------------------------------------------------------------------
646 /**
647 * Returns a copy of this year with the specified amount added.
648 * <p>
649 * This returns a {@code Year}, based on this one, with the specified amount added.
650 * The amount is typically {@link Period} but may be any other type implementing
651 * the {@link TemporalAmount} interface.
652 * <p>
653 * The calculation is delegated to the amount object by calling
654 * {@link TemporalAmount#addTo(Temporal)}. The amount implementation is free
655 * to implement the addition in any way it wishes, however it typically
656 * calls back to {@link #plus(long, TemporalUnit)}. Consult the documentation
657 * of the amount implementation to determine if it can be successfully added.
658 * <p>
659 * This instance is immutable and unaffected by this method call.
660 *
661 * @param amountToAdd the amount to add, not null
662 * @return a {@code Year} based on this year with the addition made, not null
663 * @throws DateTimeException if the addition cannot be made
664 * @throws ArithmeticException if numeric overflow occurs
665 */
666 @Override
667 public Year plus(TemporalAmount amountToAdd) {
668 return (Year) amountToAdd.addTo(this);
669 }
670
671 /**
672 * Returns a copy of this year with the specified amount added.
673 * <p>
674 * This returns a {@code Year}, based on this one, with the amount
675 * in terms of the unit added. If it is not possible to add the amount, because the
676 * unit is not supported or for some other reason, an exception is thrown.
677 * <p>
678 * If the field is a {@link ChronoUnit} then the addition is implemented here.
679 * The supported fields behave as follows:
680 * <ul>
681 * <li>{@code YEARS} -
682 * Returns a {@code Year} with the specified number of years added.
683 * This is equivalent to {@link #plusYears(long)}.
684 * <li>{@code DECADES} -
685 * Returns a {@code Year} with the specified number of decades added.
686 * This is equivalent to calling {@link #plusYears(long)} with the amount
687 * multiplied by 10.
688 * <li>{@code CENTURIES} -
689 * Returns a {@code Year} with the specified number of centuries added.
690 * This is equivalent to calling {@link #plusYears(long)} with the amount
691 * multiplied by 100.
692 * <li>{@code MILLENNIA} -
693 * Returns a {@code Year} with the specified number of millennia added.
694 * This is equivalent to calling {@link #plusYears(long)} with the amount
695 * multiplied by 1,000.
696 * <li>{@code ERAS} -
697 * Returns a {@code Year} with the specified number of eras added.
698 * Only two eras are supported so the amount must be one, zero or minus one.
699 * If the amount is non-zero then the year is changed such that the year-of-era
700 * is unchanged.
701 * </ul>
702 * <p>
703 * All other {@code ChronoUnit} instances will throw an {@code UnsupportedTemporalTypeException}.
704 * <p>
705 * If the field is not a {@code ChronoUnit}, then the result of this method
706 * is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)}
707 * passing {@code this} as the argument. In this case, the unit determines
708 * whether and how to perform the addition.
709 * <p>
710 * This instance is immutable and unaffected by this method call.
711 *
712 * @param amountToAdd the amount of the unit to add to the result, may be negative
713 * @param unit the unit of the amount to add, not null
714 * @return a {@code Year} based on this year with the specified amount added, not null
715 * @throws DateTimeException if the addition cannot be made
716 * @throws UnsupportedTemporalTypeException if the unit is not supported
717 * @throws ArithmeticException if numeric overflow occurs
718 */
719 @Override
720 public Year plus(long amountToAdd, TemporalUnit unit) {
721 if (unit instanceof ChronoUnit chronoUnit) {
722 return switch (chronoUnit) {
723 case YEARS -> plusYears(amountToAdd);
724 case DECADES -> plusYears(Math.multiplyExact(amountToAdd, 10));
725 case CENTURIES -> plusYears(Math.multiplyExact(amountToAdd, 100));
726 case MILLENNIA -> plusYears(Math.multiplyExact(amountToAdd, 1000));
727 case ERAS -> with(ERA, Math.addExact(getLong(ERA), amountToAdd));
728 default -> throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
729 };
730 }
731 return unit.addTo(this, amountToAdd);
732 }
733
734 /**
735 * Returns a copy of this {@code Year} with the specified number of years added.
736 * <p>
737 * This instance is immutable and unaffected by this method call.
738 *
739 * @param yearsToAdd the years to add, may be negative
740 * @return a {@code Year} based on this year with the years added, not null
741 * @throws DateTimeException if the result exceeds the supported range
742 */
743 public Year plusYears(long yearsToAdd) {
744 if (yearsToAdd == 0) {
745 return this;
746 }
747 return of(YEAR.checkValidIntValue(year + yearsToAdd)); // overflow safe
748 }
749
750 //-----------------------------------------------------------------------
751 /**
752 * Returns a copy of this year with the specified amount subtracted.
753 * <p>
754 * This returns a {@code Year}, based on this one, with the specified amount subtracted.
755 * The amount is typically {@link Period} but may be any other type implementing
756 * the {@link TemporalAmount} interface.
757 * <p>
758 * The calculation is delegated to the amount object by calling
759 * {@link TemporalAmount#subtractFrom(Temporal)}. The amount implementation is free
760 * to implement the subtraction in any way it wishes, however it typically
761 * calls back to {@link #minus(long, TemporalUnit)}. Consult the documentation
762 * of the amount implementation to determine if it can be successfully subtracted.
763 * <p>
764 * This instance is immutable and unaffected by this method call.
765 *
766 * @param amountToSubtract the amount to subtract, not null
767 * @return a {@code Year} based on this year with the subtraction made, not null
768 * @throws DateTimeException if the subtraction cannot be made
769 * @throws ArithmeticException if numeric overflow occurs
770 */
771 @Override
772 public Year minus(TemporalAmount amountToSubtract) {
773 return (Year) amountToSubtract.subtractFrom(this);
774 }
775
776 /**
777 * Returns a copy of this year with the specified amount subtracted.
778 * <p>
779 * This returns a {@code Year}, based on this one, with the amount
780 * in terms of the unit subtracted. If it is not possible to subtract the amount,
781 * because the unit is not supported or for some other reason, an exception is thrown.
782 * <p>
783 * This method is equivalent to {@link #plus(long, TemporalUnit)} with the amount negated.
784 * See that method for a full description of how addition, and thus subtraction, works.
785 * <p>
786 * This instance is immutable and unaffected by this method call.
787 *
788 * @param amountToSubtract the amount of the unit to subtract from the result, may be negative
789 * @param unit the unit of the amount to subtract, not null
790 * @return a {@code Year} based on this year with the specified amount subtracted, not null
791 * @throws DateTimeException if the subtraction cannot be made
792 * @throws UnsupportedTemporalTypeException if the unit is not supported
793 * @throws ArithmeticException if numeric overflow occurs
794 */
795 @Override
796 public Year minus(long amountToSubtract, TemporalUnit unit) {
797 return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
798 }
799
800 /**
801 * Returns a copy of this {@code Year} with the specified number of years subtracted.
802 * <p>
803 * This instance is immutable and unaffected by this method call.
804 *
805 * @param yearsToSubtract the years to subtract, may be negative
806 * @return a {@code Year} based on this year with the year subtracted, not null
807 * @throws DateTimeException if the result exceeds the supported range
808 */
809 public Year minusYears(long yearsToSubtract) {
810 return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract));
811 }
812
813 //-----------------------------------------------------------------------
814 /**
815 * Queries this year using the specified query.
816 * <p>
817 * This queries this year using the specified query strategy object.
818 * The {@code TemporalQuery} object defines the logic to be used to
819 * obtain the result. Read the documentation of the query to understand
820 * what the result of this method will be.
821 * <p>
822 * The result of this method is obtained by invoking the
823 * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
824 * specified query passing {@code this} as the argument.
825 *
826 * @param <R> the type of the result
827 * @param query the query to invoke, not null
828 * @return the query result, null may be returned (defined by the query)
829 * @throws DateTimeException if unable to query (defined by the query)
830 * @throws ArithmeticException if numeric overflow occurs (defined by the query)
831 */
832 @SuppressWarnings("unchecked")
833 @Override
834 public <R> R query(TemporalQuery<R> query) {
835 if (query == TemporalQueries.chronology()) {
836 return (R) IsoChronology.INSTANCE;
837 } else if (query == TemporalQueries.precision()) {
838 return (R) YEARS;
839 }
840 return Temporal.super.query(query);
841 }
842
843 /**
844 * Adjusts the specified temporal object to have this year.
845 * <p>
846 * This returns a temporal object of the same observable type as the input
847 * with the year changed to be the same as this.
848 * <p>
849 * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
850 * passing {@link ChronoField#YEAR} as the field.
851 * If the specified temporal object does not use the ISO calendar system then
852 * a {@code DateTimeException} is thrown.
853 * <p>
854 * In most cases, it is clearer to reverse the calling pattern by using
855 * {@link Temporal#with(TemporalAdjuster)}:
856 * <pre>
857 * // these two lines are equivalent, but the second approach is recommended
858 * temporal = thisYear.adjustInto(temporal);
859 * temporal = temporal.with(thisYear);
860 * </pre>
861 * <p>
862 * This instance is immutable and unaffected by this method call.
863 *
864 * @param temporal the target object to be adjusted, not null
865 * @return the adjusted object, not null
866 * @throws DateTimeException if unable to make the adjustment
867 * @throws ArithmeticException if numeric overflow occurs
868 */
869 @Override
870 public Temporal adjustInto(Temporal temporal) {
871 if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) {
872 throw new DateTimeException("Adjustment only supported on ISO date-time");
873 }
874 return temporal.with(YEAR, year);
875 }
876
877 /**
878 * Calculates the amount of time until another year in terms of the specified unit.
879 * <p>
880 * This calculates the amount of time between two {@code Year}
881 * objects in terms of a single {@code TemporalUnit}.
882 * The start and end points are {@code this} and the specified year.
883 * The result will be negative if the end is before the start.
884 * The {@code Temporal} passed to this method is converted to a
885 * {@code Year} using {@link #from(TemporalAccessor)}.
886 * For example, the amount in decades between two year can be calculated
887 * using {@code startYear.until(endYear, DECADES)}.
888 * <p>
889 * The calculation returns a whole number, representing the number of
890 * complete units between the two years.
891 * For example, the amount in decades between 2012 and 2031
892 * will only be one decade as it is one year short of two decades.
893 * <p>
894 * There are two equivalent ways of using this method.
895 * The first is to invoke this method.
896 * The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:
897 * <pre>
898 * // these two lines are equivalent
899 * amount = start.until(end, YEARS);
900 * amount = YEARS.between(start, end);
901 * </pre>
902 * The choice should be made based on which makes the code more readable.
903 * <p>
904 * The calculation is implemented in this method for {@link ChronoUnit}.
905 * The units {@code YEARS}, {@code DECADES}, {@code CENTURIES},
906 * {@code MILLENNIA} and {@code ERAS} are supported.
907 * Other {@code ChronoUnit} values will throw an exception.
908 * <p>
909 * If the unit is not a {@code ChronoUnit}, then the result of this method
910 * is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
911 * passing {@code this} as the first argument and the converted input temporal
912 * as the second argument.
913 * <p>
914 * This instance is immutable and unaffected by this method call.
915 *
916 * @param endExclusive the end date, exclusive, which is converted to a {@code Year}, not null
917 * @param unit the unit to measure the amount in, not null
918 * @return the amount of time between this year and the end year
919 * @throws DateTimeException if the amount cannot be calculated, or the end
920 * temporal cannot be converted to a {@code Year}
921 * @throws UnsupportedTemporalTypeException if the unit is not supported
922 * @throws ArithmeticException if numeric overflow occurs
923 */
924 @Override
925 public long until(Temporal endExclusive, TemporalUnit unit) {
926 Year end = Year.from(endExclusive);
927 if (unit instanceof ChronoUnit chronoUnit) {
928 long yearsUntil = ((long) end.year) - year; // no overflow
929 return switch (chronoUnit) {
930 case YEARS -> yearsUntil;
931 case DECADES -> yearsUntil / 10;
932 case CENTURIES -> yearsUntil / 100;
933 case MILLENNIA -> yearsUntil / 1000;
934 case ERAS -> end.getLong(ERA) - getLong(ERA);
935 default -> throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
936 };
937 }
938 return unit.between(this, end);
939 }
940
941 /**
942 * Formats this year using the specified formatter.
943 * <p>
944 * This year will be passed to the formatter to produce a string.
945 *
946 * @param formatter the formatter to use, not null
947 * @return the formatted year string, not null
948 * @throws DateTimeException if an error occurs during printing
949 */
950 public String format(DateTimeFormatter formatter) {
951 Objects.requireNonNull(formatter, "formatter");
952 return formatter.format(this);
953 }
954
955 //-----------------------------------------------------------------------
956 /**
957 * Combines this year with a day-of-year to create a {@code LocalDate}.
958 * <p>
959 * This returns a {@code LocalDate} formed from this year and the specified day-of-year.
960 * <p>
961 * The day-of-year value 366 is only valid in a leap year.
962 *
963 * @param dayOfYear the day-of-year to use, from 1 to 365-366
964 * @return the local date formed from this year and the specified date of year, not null
965 * @throws DateTimeException if the day of year is zero or less, 366 or greater or equal
966 * to 366 and this is not a leap year
967 */
968 public LocalDate atDay(int dayOfYear) {
969 return LocalDate.ofYearDay(year, dayOfYear);
970 }
971
972 /**
973 * Combines this year with a month to create a {@code YearMonth}.
974 * <p>
975 * This returns a {@code YearMonth} formed from this year and the specified month.
976 * All possible combinations of year and month are valid.
977 * <p>
978 * This method can be used as part of a chain to produce a date:
979 * <pre>
980 * LocalDate date = year.atMonth(month).atDay(day);
981 * </pre>
982 *
983 * @param month the month-of-year to use, not null
984 * @return the year-month formed from this year and the specified month, not null
985 */
986 public YearMonth atMonth(Month month) {
987 return YearMonth.of(year, month);
988 }
989
990 /**
991 * Combines this year with a month to create a {@code YearMonth}.
992 * <p>
993 * This returns a {@code YearMonth} formed from this year and the specified month.
994 * All possible combinations of year and month are valid.
995 * <p>
996 * This method can be used as part of a chain to produce a date:
997 * <pre>
998 * LocalDate date = year.atMonth(month).atDay(day);
999 * </pre>
1000 *
1001 * @param month the month-of-year to use, from 1 (January) to 12 (December)
1002 * @return the year-month formed from this year and the specified month, not null
1003 * @throws DateTimeException if the month is invalid
1004 */
1005 public YearMonth atMonth(int month) {
1006 return YearMonth.of(year, month);
1007 }
1008
1009 /**
1010 * Combines this year with a month-day to create a {@code LocalDate}.
1011 * <p>
1012 * This returns a {@code LocalDate} formed from this year and the specified month-day.
1013 * <p>
1014 * A month-day of February 29th will be adjusted to February 28th in the resulting
1015 * date if the year is not a leap year.
1016 *
1017 * @param monthDay the month-day to use, not null
1018 * @return the local date formed from this year and the specified month-day, not null
1019 */
1020 public LocalDate atMonthDay(MonthDay monthDay) {
1021 return monthDay.atYear(year);
1022 }
1023
1024 //-----------------------------------------------------------------------
1025 /**
1026 * Compares this year to another year.
1027 * <p>
1028 * The comparison is based on the value of the year.
1029 * It is "consistent with equals", as defined by {@link Comparable}.
1030 *
1031 * @param other the other year to compare to, not null
1032 * @return the comparator value, that is less than zero if this is before {@code other},
1033 * zero if they are equal, or greater than zero if this is after {@code other}
1034 * @see #isBefore
1035 * @see #isAfter
1036 */
1037 @Override
1038 public int compareTo(Year other) {
1039 return year - other.year;
1040 }
1041
1042 /**
1043 * Checks if this year is after the specified year.
1044 *
1045 * @param other the other year to compare to, not null
1046 * @return true if this is after the specified year
1047 */
1048 public boolean isAfter(Year other) {
1049 return year > other.year;
1050 }
1051
1052 /**
1053 * Checks if this year is before the specified year.
1054 *
1055 * @param other the other year to compare to, not null
1056 * @return true if this point is before the specified year
1057 */
1058 public boolean isBefore(Year other) {
1059 return year < other.year;
1060 }
1061
1062 //-----------------------------------------------------------------------
1063 /**
1064 * Checks if this year is equal to another year.
1065 * <p>
1066 * The comparison is based on the time-line position of the years.
1067 *
1068 * @param obj the object to check, null returns false
1069 * @return true if this is equal to the other year
1070 */
1071 @Override
1072 public boolean equals(Object obj) {
1073 if (this == obj) {
1074 return true;
1075 }
1076 if (obj instanceof Year) {
1077 return year == ((Year) obj).year;
1078 }
1079 return false;
1080 }
1081
1082 /**
1083 * A hash code for this year.
1084 *
1085 * @return a suitable hash code
1086 */
1087 @Override
1088 public int hashCode() {
1089 return year;
1090 }
1091
1092 //-----------------------------------------------------------------------
1093 /**
1094 * Outputs this year as a {@code String}.
1095 *
1096 * @return a string representation of this year, not null
1097 */
1098 @Override
1099 public String toString() {
1100 return Integer.toString(year);
1101 }
1102
1103 //-----------------------------------------------------------------------
1104 /**
1105 * Writes the object using a
1106 * <a href="{@docRoot}/serialized-form.html#java.time.Ser">dedicated serialized form</a>.
1107 * @serialData
1108 * <pre>
1109 * out.writeByte(11); // identifies a Year
1110 * out.writeInt(year);
1111 * </pre>
1112 *
1113 * @return the instance of {@code Ser}, not null
1114 */
1115 @java.io.Serial
1116 private Object writeReplace() {
1117 return new Ser(Ser.YEAR_TYPE, this);
1118 }
1119
1120 /**
1121 * Defend against malicious streams.
1122 *
1123 * @param s the stream to read
1124 * @throws InvalidObjectException always
1125 */
1126 @java.io.Serial
1127 private void readObject(ObjectInputStream s) throws InvalidObjectException {
1128 throw new InvalidObjectException("Deserialization via serialization delegate");
1129 }
1130
1131 void writeExternal(DataOutput out) throws IOException {
1132 out.writeInt(year);
1133 }
1134
1135 static Year readExternal(DataInput in) throws IOException {
1136 return Year.of(in.readInt());
1137 }
1138
1139 }