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
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 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 *
123 * <p>
124 * This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
125 * class; use of identity-sensitive operations (including reference equality
126 * ({@code ==}), identity hash code, or synchronization) on instances of
127 * {@code Year} may have unpredictable results and should be avoided.
128 * The {@code equals} method should be used for comparisons.
129 *
130 * @implSpec
131 * This class is immutable and thread-safe.
132 *
133 * @since 1.8
134 */
135 public final class Year
136 implements Temporal, TemporalAdjuster, Comparable<Year>, Serializable {
137
138 /**
139 * The minimum supported year, '-999,999,999'.
140 */
141 public static final int MIN_VALUE = -999_999_999;
142 /**
143 * The maximum supported year, '+999,999,999'.
144 */
145 public static final int MAX_VALUE = 999_999_999;
146
147 /**
148 * Serialization version.
149 */
150 @java.io.Serial
151 private static final long serialVersionUID = -23038383694477807L;
152 /**
153 * Parser.
154 */
155 private static final DateTimeFormatter PARSER = new DateTimeFormatterBuilder()
156 .appendValue(YEAR, 4, 10, SignStyle.EXCEEDS_PAD)
157 .toFormatter();
158
159 /**
160 * The year being represented.
161 */
162 private final int year;
163
164 //-----------------------------------------------------------------------
165 /**
166 * Obtains the current year from the system clock in the default time-zone.
167 * <p>
168 * This will query the {@link Clock#systemDefaultZone() system clock} in the default
169 * time-zone to obtain the current year.
170 * <p>
171 * Using this method will prevent the ability to use an alternate clock for testing
172 * because the clock is hard-coded.
173 *
174 * @return the current year using the system clock and default time-zone, not null
175 */
176 public static Year now() {
177 return now(Clock.systemDefaultZone());
178 }
179
180 /**
181 * Obtains the current year from the system clock in the specified time-zone.
182 * <p>
183 * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current year.
184 * Specifying the time-zone avoids dependence on the default time-zone.
185 * <p>
186 * Using this method will prevent the ability to use an alternate clock for testing
187 * because the clock is hard-coded.
188 *
189 * @param zone the zone ID to use, not null
190 * @return the current year using the system clock, not null
191 */
192 public static Year now(ZoneId zone) {
193 return now(Clock.system(zone));
194 }
195
196 /**
197 * Obtains the current year from the specified clock.
198 * <p>
199 * This will query the specified clock to obtain the current year.
200 * Using this method allows the use of an alternate clock for testing.
201 * The alternate clock may be introduced using {@link Clock dependency injection}.
202 *
203 * @param clock the clock to use, not null
204 * @return the current year, not null
205 */
206 public static Year now(Clock clock) {
207 final LocalDate now = LocalDate.now(clock); // called once
208 return Year.of(now.getYear());
209 }
210
211 //-----------------------------------------------------------------------
212 /**
213 * Obtains an instance of {@code Year}.
214 * <p>
215 * This method accepts a year value from the proleptic ISO calendar system.
216 * <p>
217 * The year 2AD/CE is represented by 2.<br>
218 * The year 1AD/CE is represented by 1.<br>
219 * The year 1BC/BCE is represented by 0.<br>
220 * The year 2BC/BCE is represented by -1.<br>
221 *
222 * @param isoYear the ISO proleptic year to represent, from {@code MIN_VALUE} to {@code MAX_VALUE}
223 * @return the year, not null
224 * @throws DateTimeException if the field is invalid
225 */
226 public static Year of(int isoYear) {
227 YEAR.checkValidValue(isoYear);
228 return new Year(isoYear);
229 }
230
231 //-----------------------------------------------------------------------
232 /**
233 * Obtains an instance of {@code Year} from a temporal object.
234 * <p>
235 * This obtains a year based on the specified temporal.
236 * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
237 * which this factory converts to an instance of {@code Year}.
238 * <p>
239 * The conversion extracts the {@link ChronoField#YEAR year} field.
240 * The extraction is only permitted if the temporal object has an ISO
241 * chronology, or can be converted to a {@code LocalDate}.
242 * <p>
243 * This method matches the signature of the functional interface {@link TemporalQuery}
244 * allowing it to be used as a query via method reference, {@code Year::from}.
245 *
246 * @param temporal the temporal object to convert, not null
247 * @return the year, not null
248 * @throws DateTimeException if unable to convert to a {@code Year}
249 */
250 public static Year from(TemporalAccessor temporal) {
251 if (temporal instanceof Year) {
252 return (Year) temporal;
253 }
254 Objects.requireNonNull(temporal, "temporal");
255 try {
256 if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) {
257 temporal = LocalDate.from(temporal);
258 }
259 return of(temporal.get(YEAR));
260 } catch (DateTimeException ex) {
261 throw new DateTimeException("Unable to obtain Year from TemporalAccessor: " +
262 temporal + " of type " + temporal.getClass().getName(), ex);
263 }
264 }
265
266 //-----------------------------------------------------------------------
267 /**
268 * Obtains an instance of {@code Year} from a text string such as {@code 2007}.
269 * <p>
270 * The string must represent a valid year.
271 * Years outside the range 0000 to 9999 must be prefixed by the plus or minus symbol.
272 *
273 * @param text the text to parse such as "2007", not null
274 * @return the parsed year, not null
275 * @throws DateTimeParseException if the text cannot be parsed
276 */
277 public static Year parse(CharSequence text) {
278 return parse(text, PARSER);
279 }
280
281 /**
282 * Obtains an instance of {@code Year} from a text string using a specific formatter.
283 * <p>
284 * The text is parsed using the formatter, returning a year.
285 *
286 * @param text the text to parse, not null
287 * @param formatter the formatter to use, not null
288 * @return the parsed year, not null
289 * @throws DateTimeParseException if the text cannot be parsed
290 */
291 public static Year parse(CharSequence text, DateTimeFormatter formatter) {
292 Objects.requireNonNull(formatter, "formatter");
293 return formatter.parse(text, Year::from);
294 }
295
296 //-------------------------------------------------------------------------
297 /**
298 * Checks if the year is a leap year, according to the ISO proleptic
299 * calendar system rules.
300 * <p>
301 * This method applies the current rules for leap years across the whole time-line.
302 * In general, a year is a leap year if it is divisible by four without
303 * remainder. However, years divisible by 100, are not leap years, with
304 * the exception of years divisible by 400 which are.
305 * <p>
306 * For example, 1904 is a leap year it is divisible by 4.
307 * 1900 was not a leap year as it is divisible by 100, however 2000 was a
308 * leap year as it is divisible by 400.
309 * <p>
310 * The calculation is proleptic - applying the same rules into the far future and far past.
311 * This is historically inaccurate, but is correct for the ISO-8601 standard.
312 *
313 * @param year the year to check
314 * @return true if the year is leap, false otherwise
315 */
316 public static boolean isLeap(long year) {
317 return ((year & 3) == 0) && ((year % 100) != 0 || (year % 400) == 0);
318 }
319
320 //-----------------------------------------------------------------------
321 /**
322 * Constructor.
323 *
324 * @param year the year to represent
325 */
326 private Year(int year) {
327 this.year = year;
328 }
329
330 //-----------------------------------------------------------------------
331 /**
332 * Gets the year value.
333 * <p>
334 * The year returned by this method is proleptic as per {@code get(YEAR)}.
335 *
336 * @return the year, {@code MIN_VALUE} to {@code MAX_VALUE}
337 */
338 public int getValue() {
339 return year;
340 }
341
342 //-----------------------------------------------------------------------
343 /**
344 * Checks if the specified field is supported.
345 * <p>
346 * This checks if this year can be queried for the specified field.
347 * If false, then calling the {@link #range(TemporalField) range},
348 * {@link #get(TemporalField) get} and {@link #with(TemporalField, long)}
349 * methods will throw an exception.
350 * <p>
351 * If the field is a {@link ChronoField} then the query is implemented here.
352 * The supported fields are:
353 * <ul>
354 * <li>{@code YEAR_OF_ERA}
355 * <li>{@code YEAR}
356 * <li>{@code ERA}
357 * </ul>
358 * All other {@code ChronoField} instances will return false.
359 * <p>
360 * If the field is not a {@code ChronoField}, then the result of this method
361 * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
362 * passing {@code this} as the argument.
363 * Whether the field is supported is determined by the field.
364 *
365 * @param field the field to check, null returns false
366 * @return true if the field is supported on this year, false if not
367 */
368 @Override
369 public boolean isSupported(TemporalField field) {
370 if (field instanceof ChronoField) {
371 return field == YEAR || field == YEAR_OF_ERA || field == ERA;
372 }
373 return field != null && field.isSupportedBy(this);
374 }
375
376 /**
377 * Checks if the specified unit is supported.
378 * <p>
379 * This checks if the specified unit can be added to, or subtracted from, this year.
380 * If false, then calling the {@link #plus(long, TemporalUnit)} and
381 * {@link #minus(long, TemporalUnit) minus} methods will throw an exception.
382 * <p>
383 * If the unit is a {@link ChronoUnit} then the query is implemented here.
384 * The supported units are:
385 * <ul>
386 * <li>{@code YEARS}
387 * <li>{@code DECADES}
388 * <li>{@code CENTURIES}
389 * <li>{@code MILLENNIA}
390 * <li>{@code ERAS}
391 * </ul>
392 * All other {@code ChronoUnit} instances will return false.
393 * <p>
394 * If the unit is not a {@code ChronoUnit}, then the result of this method
395 * is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}
396 * passing {@code this} as the argument.
397 * Whether the unit is supported is determined by the unit.
398 *
399 * @param unit the unit to check, null returns false
400 * @return true if the unit can be added/subtracted, false if not
401 */
402 @Override
403 public boolean isSupported(TemporalUnit unit) {
404 if (unit instanceof ChronoUnit) {
405 return unit == YEARS || unit == DECADES || unit == CENTURIES || unit == MILLENNIA || unit == ERAS;
406 }
407 return unit != null && unit.isSupportedBy(this);
408 }
409
410 //-----------------------------------------------------------------------
411 /**
412 * Gets the range of valid values for the specified field.
413 * <p>
414 * The range object expresses the minimum and maximum valid values for a field.
415 * This year is used to enhance the accuracy of the returned range.
416 * If it is not possible to return the range, because the field is not supported
417 * or for some other reason, an exception is thrown.
418 * <p>
419 * If the field is a {@link ChronoField} then the query is implemented here.
420 * The {@link #isSupported(TemporalField) supported fields} will return
421 * appropriate range instances.
422 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
423 * <p>
424 * If the field is not a {@code ChronoField}, then the result of this method
425 * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
426 * passing {@code this} as the argument.
427 * Whether the range can be obtained is determined by the field.
428 *
429 * @param field the field to query the range for, not null
430 * @return the range of valid values for the field, not null
431 * @throws DateTimeException if the range for the field cannot be obtained
432 * @throws UnsupportedTemporalTypeException if the field is not supported
433 */
434 @Override
435 public ValueRange range(TemporalField field) {
436 if (field == YEAR_OF_ERA) {
437 return (year <= 0 ? ValueRange.of(1, MAX_VALUE + 1) : ValueRange.of(1, MAX_VALUE));
438 }
439 return Temporal.super.range(field);
440 }
441
442 /**
443 * Gets the value of the specified field from this year as an {@code int}.
444 * <p>
445 * This queries this year for the value of the specified field.
446 * The returned value will always be within the valid range of values for the field.
447 * If it is not possible to return the value, because the field is not supported
448 * or for some other reason, an exception is thrown.
449 * <p>
450 * If the field is a {@link ChronoField} then the query is implemented here.
451 * The {@link #isSupported(TemporalField) supported fields} will return valid
452 * values based on this year.
453 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
454 * <p>
455 * If the field is not a {@code ChronoField}, then the result of this method
456 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
457 * passing {@code this} as the argument. Whether the value can be obtained,
458 * and what the value represents, is determined by the field.
459 *
460 * @param field the field to get, not null
461 * @return the value for the field
462 * @throws DateTimeException if a value for the field cannot be obtained or
463 * the value is outside the range of valid values for the field
464 * @throws UnsupportedTemporalTypeException if the field is not supported or
465 * the range of values exceeds an {@code int}
466 * @throws ArithmeticException if numeric overflow occurs
467 */
468 @Override // override for Javadoc
469 public int get(TemporalField field) {
470 return range(field).checkValidIntValue(getLong(field), field);
471 }
472
473 /**
474 * Gets the value of the specified field from this year as a {@code long}.
475 * <p>
476 * This queries this year for the value of the specified field.
477 * If it is not possible to return the value, because the field is not supported
478 * or for some other reason, an exception is thrown.
479 * <p>
480 * If the field is a {@link ChronoField} then the query is implemented here.
481 * The {@link #isSupported(TemporalField) supported fields} will return valid
482 * values based on this year.
483 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
484 * <p>
485 * If the field is not a {@code ChronoField}, then the result of this method
486 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
487 * passing {@code this} as the argument. Whether the value can be obtained,
488 * and what the value represents, is determined by the field.
489 *
490 * @param field the field to get, not null
491 * @return the value for the field
492 * @throws DateTimeException if a value for the field cannot be obtained
493 * @throws UnsupportedTemporalTypeException if the field is not supported
494 * @throws ArithmeticException if numeric overflow occurs
495 */
496 @Override
497 public long getLong(TemporalField field) {
498 if (field instanceof ChronoField) {
499 switch ((ChronoField) field) {
500 case YEAR_OF_ERA: return (year < 1 ? 1 - year : year);
501 case YEAR: return year;
502 case ERA: return (year < 1 ? 0 : 1);
503 }
504 throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
505 }
506 return field.getFrom(this);
507 }
508
509 //-----------------------------------------------------------------------
510 /**
511 * Checks if the year is a leap year, according to the ISO proleptic
512 * calendar system rules.
513 * <p>
514 * This method applies the current rules for leap years across the whole time-line.
515 * In general, a year is a leap year if it is divisible by four without
516 * remainder. However, years divisible by 100, are not leap years, with
517 * the exception of years divisible by 400 which are.
518 * <p>
519 * For example, 1904 is a leap year it is divisible by 4.
520 * 1900 was not a leap year as it is divisible by 100, however 2000 was a
521 * leap year as it is divisible by 400.
522 * <p>
523 * The calculation is proleptic - applying the same rules into the far future and far past.
524 * This is historically inaccurate, but is correct for the ISO-8601 standard.
525 *
526 * @return true if the year is leap, false otherwise
527 */
528 public boolean isLeap() {
529 return Year.isLeap(year);
530 }
531
532 /**
533 * Checks if the month-day is valid for this year.
534 * <p>
535 * This method checks whether this year and the input month and day form
536 * a valid date.
537 *
538 * @param monthDay the month-day to validate, null returns false
539 * @return true if the month and day are valid for this year
540 */
541 public boolean isValidMonthDay(MonthDay monthDay) {
542 return monthDay != null && monthDay.isValidYear(year);
543 }
544
545 /**
546 * Gets the length of this year in days.
547 *
548 * @return the length of this year in days, 365 or 366
549 */
550 public int length() {
551 return isLeap() ? 366 : 365;
552 }
553
554 //-----------------------------------------------------------------------
555 /**
556 * Returns an adjusted copy of this year.
557 * <p>
558 * This returns a {@code Year}, based on this one, with the year adjusted.
559 * The adjustment takes place using the specified adjuster strategy object.
560 * Read the documentation of the adjuster to understand what adjustment will be made.
561 * <p>
562 * The result of this method is obtained by invoking the
563 * {@link TemporalAdjuster#adjustInto(Temporal)} method on the
564 * specified adjuster passing {@code this} as the argument.
565 * <p>
566 * This instance is immutable and unaffected by this method call.
567 *
568 * @param adjuster the adjuster to use, not null
569 * @return a {@code Year} based on {@code this} with the adjustment made, not null
570 * @throws DateTimeException if the adjustment cannot be made
571 * @throws ArithmeticException if numeric overflow occurs
572 */
573 @Override
574 public Year with(TemporalAdjuster adjuster) {
575 return (Year) adjuster.adjustInto(this);
576 }
577
578 /**
579 * Returns a copy of this year with the specified field set to a new value.
580 * <p>
581 * This returns a {@code Year}, based on this one, with the value
582 * for the specified field changed.
583 * If it is not possible to set the value, because the field is not supported or for
584 * some other reason, an exception is thrown.
585 * <p>
586 * If the field is a {@link ChronoField} then the adjustment is implemented here.
587 * The supported fields behave as follows:
588 * <ul>
589 * <li>{@code YEAR_OF_ERA} -
590 * Returns a {@code Year} with the specified year-of-era
591 * The era will be unchanged.
592 * <li>{@code YEAR} -
593 * Returns a {@code Year} with the specified year.
594 * This completely replaces the date and is equivalent to {@link #of(int)}.
595 * <li>{@code ERA} -
596 * Returns a {@code Year} with the specified era.
597 * The year-of-era will be unchanged.
598 * </ul>
599 * <p>
600 * In all cases, if the new value is outside the valid range of values for the field
601 * then a {@code DateTimeException} will be thrown.
602 * <p>
603 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
604 * <p>
605 * If the field is not a {@code ChronoField}, then the result of this method
606 * is obtained by invoking {@code TemporalField.adjustInto(Temporal, long)}
607 * passing {@code this} as the argument. In this case, the field determines
608 * whether and how to adjust the instant.
609 * <p>
610 * This instance is immutable and unaffected by this method call.
611 *
612 * @param field the field to set in the result, not null
613 * @param newValue the new value of the field in the result
614 * @return a {@code Year} based on {@code this} with the specified field set, not null
615 * @throws DateTimeException if the field cannot be set
616 * @throws UnsupportedTemporalTypeException if the field is not supported
617 * @throws ArithmeticException if numeric overflow occurs
618 */
619 @Override
620 public Year with(TemporalField field, long newValue) {
621 if (field instanceof ChronoField) {
622 ChronoField f = (ChronoField) field;
623 f.checkValidValue(newValue);
624 switch (f) {
625 case YEAR_OF_ERA: return Year.of((int) (year < 1 ? 1 - newValue : newValue));
626 case YEAR: return Year.of((int) newValue);
627 case ERA: return (getLong(ERA) == newValue ? this : Year.of(1 - year));
628 }
629 throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
630 }
631 return field.adjustInto(this, newValue);
632 }
633
634 //-----------------------------------------------------------------------
635 /**
636 * Returns a copy of this year with the specified amount added.
637 * <p>
638 * This returns a {@code Year}, based on this one, with the specified amount added.
639 * The amount is typically {@link Period} but may be any other type implementing
640 * the {@link TemporalAmount} interface.
641 * <p>
642 * The calculation is delegated to the amount object by calling
643 * {@link TemporalAmount#addTo(Temporal)}. The amount implementation is free
644 * to implement the addition in any way it wishes, however it typically
645 * calls back to {@link #plus(long, TemporalUnit)}. Consult the documentation
646 * of the amount implementation to determine if it can be successfully added.
647 * <p>
648 * This instance is immutable and unaffected by this method call.
649 *
650 * @param amountToAdd the amount to add, not null
651 * @return a {@code Year} based on this year with the addition made, not null
652 * @throws DateTimeException if the addition cannot be made
653 * @throws ArithmeticException if numeric overflow occurs
654 */
655 @Override
656 public Year plus(TemporalAmount amountToAdd) {
657 return (Year) amountToAdd.addTo(this);
658 }
659
660 /**
661 * Returns a copy of this year with the specified amount added.
662 * <p>
663 * This returns a {@code Year}, based on this one, with the amount
664 * in terms of the unit added. If it is not possible to add the amount, because the
665 * unit is not supported or for some other reason, an exception is thrown.
666 * <p>
667 * If the field is a {@link ChronoUnit} then the addition is implemented here.
668 * The supported fields behave as follows:
669 * <ul>
670 * <li>{@code YEARS} -
671 * Returns a {@code Year} with the specified number of years added.
672 * This is equivalent to {@link #plusYears(long)}.
673 * <li>{@code DECADES} -
674 * Returns a {@code Year} with the specified number of decades added.
675 * This is equivalent to calling {@link #plusYears(long)} with the amount
676 * multiplied by 10.
677 * <li>{@code CENTURIES} -
678 * Returns a {@code Year} with the specified number of centuries added.
679 * This is equivalent to calling {@link #plusYears(long)} with the amount
680 * multiplied by 100.
681 * <li>{@code MILLENNIA} -
682 * Returns a {@code Year} with the specified number of millennia added.
683 * This is equivalent to calling {@link #plusYears(long)} with the amount
684 * multiplied by 1,000.
685 * <li>{@code ERAS} -
686 * Returns a {@code Year} with the specified number of eras added.
687 * Only two eras are supported so the amount must be one, zero or minus one.
688 * If the amount is non-zero then the year is changed such that the year-of-era
689 * is unchanged.
690 * </ul>
691 * <p>
692 * All other {@code ChronoUnit} instances will throw an {@code UnsupportedTemporalTypeException}.
693 * <p>
694 * If the field is not a {@code ChronoUnit}, then the result of this method
695 * is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)}
696 * passing {@code this} as the argument. In this case, the unit determines
697 * whether and how to perform the addition.
698 * <p>
699 * This instance is immutable and unaffected by this method call.
700 *
701 * @param amountToAdd the amount of the unit to add to the result, may be negative
702 * @param unit the unit of the amount to add, not null
703 * @return a {@code Year} based on this year with the specified amount added, not null
704 * @throws DateTimeException if the addition cannot be made
705 * @throws UnsupportedTemporalTypeException if the unit is not supported
706 * @throws ArithmeticException if numeric overflow occurs
707 */
708 @Override
709 public Year plus(long amountToAdd, TemporalUnit unit) {
710 if (unit instanceof ChronoUnit) {
711 switch ((ChronoUnit) unit) {
712 case YEARS: return plusYears(amountToAdd);
713 case DECADES: return plusYears(Math.multiplyExact(amountToAdd, 10));
714 case CENTURIES: return plusYears(Math.multiplyExact(amountToAdd, 100));
715 case MILLENNIA: return plusYears(Math.multiplyExact(amountToAdd, 1000));
716 case ERAS: return with(ERA, Math.addExact(getLong(ERA), amountToAdd));
717 }
718 throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
719 }
720 return unit.addTo(this, amountToAdd);
721 }
722
723 /**
724 * Returns a copy of this {@code Year} with the specified number of years added.
725 * <p>
726 * This instance is immutable and unaffected by this method call.
727 *
728 * @param yearsToAdd the years to add, may be negative
729 * @return a {@code Year} based on this year with the years added, not null
730 * @throws DateTimeException if the result exceeds the supported range
731 */
732 public Year plusYears(long yearsToAdd) {
733 if (yearsToAdd == 0) {
734 return this;
735 }
736 return of(YEAR.checkValidIntValue(year + yearsToAdd)); // overflow safe
737 }
738
739 //-----------------------------------------------------------------------
740 /**
741 * Returns a copy of this year with the specified amount subtracted.
742 * <p>
743 * This returns a {@code Year}, based on this one, with the specified amount subtracted.
744 * The amount is typically {@link Period} but may be any other type implementing
745 * the {@link TemporalAmount} interface.
746 * <p>
747 * The calculation is delegated to the amount object by calling
748 * {@link TemporalAmount#subtractFrom(Temporal)}. The amount implementation is free
749 * to implement the subtraction in any way it wishes, however it typically
750 * calls back to {@link #minus(long, TemporalUnit)}. Consult the documentation
751 * of the amount implementation to determine if it can be successfully subtracted.
752 * <p>
753 * This instance is immutable and unaffected by this method call.
754 *
755 * @param amountToSubtract the amount to subtract, not null
756 * @return a {@code Year} based on this year with the subtraction made, not null
757 * @throws DateTimeException if the subtraction cannot be made
758 * @throws ArithmeticException if numeric overflow occurs
759 */
760 @Override
761 public Year minus(TemporalAmount amountToSubtract) {
762 return (Year) amountToSubtract.subtractFrom(this);
763 }
764
765 /**
766 * Returns a copy of this year with the specified amount subtracted.
767 * <p>
768 * This returns a {@code Year}, based on this one, with the amount
769 * in terms of the unit subtracted. If it is not possible to subtract the amount,
770 * because the unit is not supported or for some other reason, an exception is thrown.
771 * <p>
772 * This method is equivalent to {@link #plus(long, TemporalUnit)} with the amount negated.
773 * See that method for a full description of how addition, and thus subtraction, works.
774 * <p>
775 * This instance is immutable and unaffected by this method call.
776 *
777 * @param amountToSubtract the amount of the unit to subtract from the result, may be negative
778 * @param unit the unit of the amount to subtract, not null
779 * @return a {@code Year} based on this year with the specified amount subtracted, not null
780 * @throws DateTimeException if the subtraction cannot be made
781 * @throws UnsupportedTemporalTypeException if the unit is not supported
782 * @throws ArithmeticException if numeric overflow occurs
783 */
784 @Override
785 public Year minus(long amountToSubtract, TemporalUnit unit) {
786 return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
787 }
788
789 /**
790 * Returns a copy of this {@code Year} with the specified number of years subtracted.
791 * <p>
792 * This instance is immutable and unaffected by this method call.
793 *
794 * @param yearsToSubtract the years to subtract, may be negative
795 * @return a {@code Year} based on this year with the year subtracted, not null
796 * @throws DateTimeException if the result exceeds the supported range
797 */
798 public Year minusYears(long yearsToSubtract) {
799 return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract));
800 }
801
802 //-----------------------------------------------------------------------
803 /**
804 * Queries this year using the specified query.
805 * <p>
806 * This queries this year using the specified query strategy object.
807 * The {@code TemporalQuery} object defines the logic to be used to
808 * obtain the result. Read the documentation of the query to understand
809 * what the result of this method will be.
810 * <p>
811 * The result of this method is obtained by invoking the
812 * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
813 * specified query passing {@code this} as the argument.
814 *
815 * @param <R> the type of the result
816 * @param query the query to invoke, not null
817 * @return the query result, null may be returned (defined by the query)
818 * @throws DateTimeException if unable to query (defined by the query)
819 * @throws ArithmeticException if numeric overflow occurs (defined by the query)
820 */
821 @SuppressWarnings("unchecked")
822 @Override
823 public <R> R query(TemporalQuery<R> query) {
824 if (query == TemporalQueries.chronology()) {
825 return (R) IsoChronology.INSTANCE;
826 } else if (query == TemporalQueries.precision()) {
827 return (R) YEARS;
828 }
829 return Temporal.super.query(query);
830 }
831
832 /**
833 * Adjusts the specified temporal object to have this year.
834 * <p>
835 * This returns a temporal object of the same observable type as the input
836 * with the year changed to be the same as this.
837 * <p>
838 * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
839 * passing {@link ChronoField#YEAR} as the field.
840 * If the specified temporal object does not use the ISO calendar system then
841 * a {@code DateTimeException} is thrown.
842 * <p>
843 * In most cases, it is clearer to reverse the calling pattern by using
844 * {@link Temporal#with(TemporalAdjuster)}:
845 * <pre>
846 * // these two lines are equivalent, but the second approach is recommended
847 * temporal = thisYear.adjustInto(temporal);
848 * temporal = temporal.with(thisYear);
849 * </pre>
850 * <p>
851 * This instance is immutable and unaffected by this method call.
852 *
853 * @param temporal the target object to be adjusted, not null
854 * @return the adjusted object, not null
855 * @throws DateTimeException if unable to make the adjustment
856 * @throws ArithmeticException if numeric overflow occurs
857 */
858 @Override
859 public Temporal adjustInto(Temporal temporal) {
860 if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) {
861 throw new DateTimeException("Adjustment only supported on ISO date-time");
862 }
863 return temporal.with(YEAR, year);
864 }
865
866 /**
867 * Calculates the amount of time until another year in terms of the specified unit.
868 * <p>
869 * This calculates the amount of time between two {@code Year}
870 * objects in terms of a single {@code TemporalUnit}.
871 * The start and end points are {@code this} and the specified year.
872 * The result will be negative if the end is before the start.
873 * The {@code Temporal} passed to this method is converted to a
874 * {@code Year} using {@link #from(TemporalAccessor)}.
875 * For example, the amount in decades between two year can be calculated
876 * using {@code startYear.until(endYear, DECADES)}.
877 * <p>
878 * The calculation returns a whole number, representing the number of
879 * complete units between the two years.
880 * For example, the amount in decades between 2012 and 2031
881 * will only be one decade as it is one year short of two decades.
882 * <p>
883 * There are two equivalent ways of using this method.
884 * The first is to invoke this method.
885 * The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:
886 * <pre>
887 * // these two lines are equivalent
888 * amount = start.until(end, YEARS);
889 * amount = YEARS.between(start, end);
890 * </pre>
891 * The choice should be made based on which makes the code more readable.
892 * <p>
893 * The calculation is implemented in this method for {@link ChronoUnit}.
894 * The units {@code YEARS}, {@code DECADES}, {@code CENTURIES},
895 * {@code MILLENNIA} and {@code ERAS} are supported.
896 * Other {@code ChronoUnit} values will throw an exception.
897 * <p>
898 * If the unit is not a {@code ChronoUnit}, then the result of this method
899 * is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
900 * passing {@code this} as the first argument and the converted input temporal
901 * as the second argument.
902 * <p>
903 * This instance is immutable and unaffected by this method call.
904 *
905 * @param endExclusive the end date, exclusive, which is converted to a {@code Year}, not null
906 * @param unit the unit to measure the amount in, not null
907 * @return the amount of time between this year and the end year
908 * @throws DateTimeException if the amount cannot be calculated, or the end
909 * temporal cannot be converted to a {@code Year}
910 * @throws UnsupportedTemporalTypeException if the unit is not supported
911 * @throws ArithmeticException if numeric overflow occurs
912 */
913 @Override
914 public long until(Temporal endExclusive, TemporalUnit unit) {
915 Year end = Year.from(endExclusive);
916 if (unit instanceof ChronoUnit) {
917 long yearsUntil = ((long) end.year) - year; // no overflow
918 switch ((ChronoUnit) unit) {
919 case YEARS: return yearsUntil;
920 case DECADES: return yearsUntil / 10;
921 case CENTURIES: return yearsUntil / 100;
922 case MILLENNIA: return yearsUntil / 1000;
923 case ERAS: return end.getLong(ERA) - getLong(ERA);
924 }
925 throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
926 }
927 return unit.between(this, end);
928 }
929
930 /**
931 * Formats this year using the specified formatter.
932 * <p>
933 * This year will be passed to the formatter to produce a string.
934 *
935 * @param formatter the formatter to use, not null
936 * @return the formatted year string, not null
937 * @throws DateTimeException if an error occurs during printing
938 */
939 public String format(DateTimeFormatter formatter) {
940 Objects.requireNonNull(formatter, "formatter");
941 return formatter.format(this);
942 }
943
944 //-----------------------------------------------------------------------
945 /**
946 * Combines this year with a day-of-year to create a {@code LocalDate}.
947 * <p>
948 * This returns a {@code LocalDate} formed from this year and the specified day-of-year.
949 * <p>
950 * The day-of-year value 366 is only valid in a leap year.
951 *
952 * @param dayOfYear the day-of-year to use, from 1 to 365-366
953 * @return the local date formed from this year and the specified date of year, not null
954 * @throws DateTimeException if the day of year is zero or less, 366 or greater or equal
955 * to 366 and this is not a leap year
956 */
957 public LocalDate atDay(int dayOfYear) {
958 return LocalDate.ofYearDay(year, dayOfYear);
959 }
960
961 /**
962 * Combines this year with a month to create a {@code YearMonth}.
963 * <p>
964 * This returns a {@code YearMonth} formed from this year and the specified month.
965 * All possible combinations of year and month are valid.
966 * <p>
967 * This method can be used as part of a chain to produce a date:
968 * <pre>
969 * LocalDate date = year.atMonth(month).atDay(day);
970 * </pre>
971 *
972 * @param month the month-of-year to use, not null
973 * @return the year-month formed from this year and the specified month, not null
974 */
975 public YearMonth atMonth(Month month) {
976 return YearMonth.of(year, month);
977 }
978
979 /**
980 * Combines this year with a month to create a {@code YearMonth}.
981 * <p>
982 * This returns a {@code YearMonth} formed from this year and the specified month.
983 * All possible combinations of year and month are valid.
984 * <p>
985 * This method can be used as part of a chain to produce a date:
986 * <pre>
987 * LocalDate date = year.atMonth(month).atDay(day);
988 * </pre>
989 *
990 * @param month the month-of-year to use, from 1 (January) to 12 (December)
991 * @return the year-month formed from this year and the specified month, not null
992 * @throws DateTimeException if the month is invalid
993 */
994 public YearMonth atMonth(int month) {
995 return YearMonth.of(year, month);
996 }
997
998 /**
999 * Combines this year with a month-day to create a {@code LocalDate}.
1000 * <p>
1001 * This returns a {@code LocalDate} formed from this year and the specified month-day.
1002 * <p>
1003 * A month-day of February 29th will be adjusted to February 28th in the resulting
1004 * date if the year is not a leap year.
1005 *
1006 * @param monthDay the month-day to use, not null
1007 * @return the local date formed from this year and the specified month-day, not null
1008 */
1009 public LocalDate atMonthDay(MonthDay monthDay) {
1010 return monthDay.atYear(year);
1011 }
1012
1013 //-----------------------------------------------------------------------
1014 /**
1015 * Compares this year to another year.
1016 * <p>
1017 * The comparison is based on the value of the year.
1018 * It is "consistent with equals", as defined by {@link Comparable}.
1019 *
1020 * @param other the other year to compare to, not null
1021 * @return the comparator value, negative if less, positive if greater
1022 */
1023 @Override
1024 public int compareTo(Year other) {
1025 return year - other.year;
1026 }
1027
1028 /**
1029 * Checks if this year is after the specified year.
1030 *
1031 * @param other the other year to compare to, not null
1032 * @return true if this is after the specified year
1033 */
1034 public boolean isAfter(Year other) {
1035 return year > other.year;
1036 }
1037
1038 /**
1039 * Checks if this year is before the specified year.
1040 *
1041 * @param other the other year to compare to, not null
1042 * @return true if this point is before the specified year
1043 */
1044 public boolean isBefore(Year other) {
1045 return year < other.year;
1046 }
1047
1048 //-----------------------------------------------------------------------
1049 /**
1050 * Checks if this year is equal to another year.
1051 * <p>
1052 * The comparison is based on the time-line position of the years.
1053 *
1054 * @param obj the object to check, null returns false
1055 * @return true if this is equal to the other year
1056 */
1057 @Override
1058 public boolean equals(Object obj) {
1059 if (this == obj) {
1060 return true;
1061 }
1062 if (obj instanceof Year) {
1063 return year == ((Year) obj).year;
1064 }
1065 return false;
1066 }
1067
1068 /**
1069 * A hash code for this year.
1070 *
1071 * @return a suitable hash code
1072 */
1073 @Override
1074 public int hashCode() {
1075 return year;
1076 }
1077
1078 //-----------------------------------------------------------------------
1079 /**
1080 * Outputs this year as a {@code String}.
1081 *
1082 * @return a string representation of this year, not null
1083 */
1084 @Override
1085 public String toString() {
1086 return Integer.toString(year);
1087 }
1088
1089 //-----------------------------------------------------------------------
1090 /**
1091 * Writes the object using a
1092 * <a href="{@docRoot}/serialized-form.html#java.time.Ser">dedicated serialized form</a>.
1093 * @serialData
1094 * <pre>
1095 * out.writeByte(11); // identifies a Year
1096 * out.writeInt(year);
1097 * </pre>
1098 *
1099 * @return the instance of {@code Ser}, not null
1100 */
1101 @java.io.Serial
1102 private Object writeReplace() {
1103 return new Ser(Ser.YEAR_TYPE, this);
1104 }
1105
1106 /**
1107 * Defend against malicious streams.
1108 *
1109 * @param s the stream to read
1110 * @throws InvalidObjectException always
1111 */
1112 @java.io.Serial
1113 private void readObject(ObjectInputStream s) throws InvalidObjectException {
1114 throw new InvalidObjectException("Deserialization via serialization delegate");
1115 }
1116
1117 void writeExternal(DataOutput out) throws IOException {
1118 out.writeInt(year);
1119 }
1120
1121 static Year readExternal(DataInput in) throws IOException {
1122 return Year.of(in.readInt());
1123 }
1124
1125 }