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