1 /*
2 * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 /*
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file:
31 *
32 * Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
33 *
34 * All rights reserved.
35 *
36 * Redistribution and use in source and binary forms, with or without
37 * modification, are permitted provided that the following conditions are met:
38 *
39 * * Redistributions of source code must retain the above copyright notice,
40 * this list of conditions and the following disclaimer.
41 *
42 * * Redistributions in binary form must reproduce the above copyright notice,
43 * this list of conditions and the following disclaimer in the documentation
44 * and/or other materials provided with the distribution.
45 *
46 * * Neither the name of JSR-310 nor the names of its contributors
47 * may be used to endorse or promote products derived from this software
48 * without specific prior written permission.
49 *
50 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
51 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
52 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
53 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
54 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
55 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
56 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
57 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
58 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
59 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
60 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
61 */
62 package java.time;
63
64 import 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.YEARS;
68
69 import java.io.DataInput;
70 import java.io.DataOutput;
71 import java.io.IOException;
72 import java.io.InvalidObjectException;
73 import java.io.ObjectStreamException;
74 import java.io.Serializable;
75 import java.time.chrono.Chronology;
76 import java.time.chrono.IsoChronology;
77 import java.time.format.DateTimeFormatter;
78 import java.time.format.DateTimeFormatterBuilder;
79 import java.time.format.DateTimeParseException;
80 import java.time.format.SignStyle;
81 import java.time.temporal.ChronoField;
82 import java.time.temporal.ChronoUnit;
83 import java.time.temporal.Queries;
84 import java.time.temporal.Temporal;
85 import java.time.temporal.TemporalAccessor;
86 import java.time.temporal.TemporalAdjuster;
87 import java.time.temporal.TemporalAmount;
88 import java.time.temporal.TemporalField;
89 import java.time.temporal.TemporalQuery;
90 import java.time.temporal.TemporalUnit;
91 import java.time.temporal.ValueRange;
92 import java.util.Objects;
93
94 /**
95 * A year in the ISO-8601 calendar system, such as {@code 2007}.
96 * <p>
97 * {@code Year} is an immutable date-time object that represents a year.
98 * Any field that can be derived from a year can be obtained.
99 * <p>
100 * <b>Note that years in the ISO chronology only align with years in the
101 * Gregorian-Julian system for modern years. Parts of Russia did not switch to the
102 * modern Gregorian/ISO rules until 1920.
103 * As such, historical years must be treated with caution.</b>
104 * <p>
105 * This class does not store or represent a month, day, time or time-zone.
106 * For example, the value "2007" can be stored in a {@code Year}.
107 * <p>
108 * Years represented by this class follow the ISO-8601 standard and use
109 * the proleptic numbering system. Year 1 is preceded by year 0, then by year -1.
110 * <p>
111 * The ISO-8601 calendar system is the modern civil calendar system used today
112 * in most of the world. It is equivalent to the proleptic Gregorian calendar
113 * system, in which today's rules for leap years are applied for all time.
114 * For most applications written today, the ISO-8601 rules are entirely suitable.
115 * However, any application that makes use of historical dates, and requires them
116 * to be accurate will find the ISO-8601 approach unsuitable.
117 *
118 * <h3>Specification for implementors</h3>
119 * This class is immutable and thread-safe.
120 *
121 * @since 1.8
122 */
123 public final class Year
124 implements Temporal, TemporalAdjuster, Comparable<Year>, Serializable {
125
126 /**
127 * The minimum supported year, '-999,999,999'.
128 */
129 public static final int MIN_VALUE = -999_999_999;
130 /**
131 * The maximum supported year, '+999,999,999'.
132 */
133 public static final int MAX_VALUE = 999_999_999;
134
135 /**
136 * Serialization version.
137 */
138 private static final long serialVersionUID = -23038383694477807L;
139 /**
140 * Parser.
141 */
142 private static final DateTimeFormatter PARSER = new DateTimeFormatterBuilder()
143 .appendValue(YEAR, 4, 10, SignStyle.EXCEEDS_PAD)
144 .toFormatter();
145
146 /**
147 * The year being represented.
148 */
149 private final int year;
150
151 //-----------------------------------------------------------------------
152 /**
153 * Obtains the current year from the system clock in the default time-zone.
154 * <p>
155 * This will query the {@link java.time.Clock#systemDefaultZone() system clock} in the default
156 * time-zone to obtain the current year.
157 * <p>
158 * Using this method will prevent the ability to use an alternate clock for testing
159 * because the clock is hard-coded.
160 *
161 * @return the current year using the system clock and default time-zone, not null
162 */
163 public static Year now() {
164 return now(Clock.systemDefaultZone());
165 }
166
167 /**
168 * Obtains the current year from the system clock in the specified time-zone.
169 * <p>
170 * This will query the {@link Clock#system(java.time.ZoneId) system clock} to obtain the current year.
171 * Specifying the time-zone avoids dependence on the default time-zone.
172 * <p>
173 * Using this method will prevent the ability to use an alternate clock for testing
174 * because the clock is hard-coded.
175 *
176 * @param zone the zone ID to use, not null
177 * @return the current year using the system clock, not null
178 */
179 public static Year now(ZoneId zone) {
180 return now(Clock.system(zone));
181 }
182
183 /**
184 * Obtains the current year from the specified clock.
185 * <p>
186 * This will query the specified clock to obtain the current year.
187 * Using this method allows the use of an alternate clock for testing.
188 * The alternate clock may be introduced using {@link Clock dependency injection}.
189 *
190 * @param clock the clock to use, not null
191 * @return the current year, not null
192 */
193 public static Year now(Clock clock) {
194 final LocalDate now = LocalDate.now(clock); // called once
195 return Year.of(now.getYear());
196 }
197
198 //-----------------------------------------------------------------------
199 /**
200 * Obtains an instance of {@code Year}.
201 * <p>
202 * This method accepts a year value from the proleptic ISO calendar system.
203 * <p>
204 * The year 2AD/CE is represented by 2.<br>
205 * The year 1AD/CE is represented by 1.<br>
206 * The year 1BC/BCE is represented by 0.<br>
207 * The year 2BC/BCE is represented by -1.<br>
208 *
209 * @param isoYear the ISO proleptic year to represent, from {@code MIN_VALUE} to {@code MAX_VALUE}
210 * @return the year, not null
211 * @throws DateTimeException if the field is invalid
212 */
213 public static Year of(int isoYear) {
214 YEAR.checkValidValue(isoYear);
215 return new Year(isoYear);
216 }
217
218 //-----------------------------------------------------------------------
219 /**
220 * Obtains an instance of {@code Year} from a temporal object.
221 * <p>
222 * This obtains a year based on the specified temporal.
223 * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
224 * which this factory converts to an instance of {@code Year}.
225 * <p>
226 * The conversion extracts the {@link ChronoField#YEAR year} field.
227 * The extraction is only permitted if the temporal object has an ISO
228 * chronology, or can be converted to a {@code LocalDate}.
229 * <p>
230 * This method matches the signature of the functional interface {@link TemporalQuery}
231 * allowing it to be used in queries via method reference, {@code Year::from}.
232 *
233 * @param temporal the temporal object to convert, not null
234 * @return the year, not null
235 * @throws DateTimeException if unable to convert to a {@code Year}
236 */
237 public static Year from(TemporalAccessor temporal) {
238 if (temporal instanceof Year) {
239 return (Year) temporal;
240 }
241 try {
242 if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) {
243 temporal = LocalDate.from(temporal);
244 }
245 return of(temporal.get(YEAR));
246 } catch (DateTimeException ex) {
247 throw new DateTimeException("Unable to obtain Year from TemporalAccessor: " + temporal.getClass(), ex);
248 }
249 }
250
251 //-----------------------------------------------------------------------
252 /**
253 * Obtains an instance of {@code Year} from a text string such as {@code 2007}.
254 * <p>
255 * The string must represent a valid year.
256 * Years outside the range 0000 to 9999 must be prefixed by the plus or minus symbol.
257 *
258 * @param text the text to parse such as "2007", not null
259 * @return the parsed year, not null
260 * @throws DateTimeParseException if the text cannot be parsed
261 */
262 public static Year parse(CharSequence text) {
263 return parse(text, PARSER);
264 }
265
266 /**
267 * Obtains an instance of {@code Year} from a text string using a specific formatter.
268 * <p>
269 * The text is parsed using the formatter, returning a year.
270 *
271 * @param text the text to parse, not null
272 * @param formatter the formatter to use, 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, DateTimeFormatter formatter) {
277 Objects.requireNonNull(formatter, "formatter");
278 return formatter.parse(text, Year::from);
279 }
280
281 //-------------------------------------------------------------------------
282 /**
283 * Checks if the year is a leap year, according to the ISO proleptic
284 * calendar system rules.
285 * <p>
286 * This method applies the current rules for leap years across the whole time-line.
287 * In general, a year is a leap year if it is divisible by four without
288 * remainder. However, years divisible by 100, are not leap years, with
289 * the exception of years divisible by 400 which are.
290 * <p>
291 * For example, 1904 is a leap year it is divisible by 4.
292 * 1900 was not a leap year as it is divisible by 100, however 2000 was a
293 * leap year as it is divisible by 400.
294 * <p>
295 * The calculation is proleptic - applying the same rules into the far future and far past.
296 * This is historically inaccurate, but is correct for the ISO-8601 standard.
297 *
298 * @param year the year to check
299 * @return true if the year is leap, false otherwise
300 */
301 public static boolean isLeap(long year) {
302 return ((year & 3) == 0) && ((year % 100) != 0 || (year % 400) == 0);
303 }
304
305 //-----------------------------------------------------------------------
306 /**
307 * Constructor.
308 *
309 * @param year the year to represent
310 */
311 private Year(int year) {
312 this.year = year;
313 }
314
315 //-----------------------------------------------------------------------
316 /**
317 * Gets the year value.
318 * <p>
319 * The year returned by this method is proleptic as per {@code get(YEAR)}.
320 *
321 * @return the year, {@code MIN_VALUE} to {@code MAX_VALUE}
322 */
323 public int getValue() {
324 return year;
325 }
326
327 //-----------------------------------------------------------------------
328 /**
329 * Checks if the specified field is supported.
330 * <p>
331 * This checks if this year can be queried for the specified field.
332 * If false, then calling the {@link #range(TemporalField) range} and
333 * {@link #get(TemporalField) get} methods will throw an exception.
334 * <p>
335 * If the field is a {@link ChronoField} then the query is implemented here.
336 * The supported fields are:
337 * <ul>
338 * <li>{@code YEAR_OF_ERA}
339 * <li>{@code YEAR}
340 * <li>{@code ERA}
341 * </ul>
342 * All other {@code ChronoField} instances will return false.
343 * <p>
344 * If the field is not a {@code ChronoField}, then the result of this method
345 * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
346 * passing {@code this} as the argument.
347 * Whether the field is supported is determined by the field.
348 *
349 * @param field the field to check, null returns false
350 * @return true if the field is supported on this year, false if not
351 */
352 @Override
353 public boolean isSupported(TemporalField field) {
354 if (field instanceof ChronoField) {
355 return field == YEAR || field == YEAR_OF_ERA || field == ERA;
356 }
357 return field != null && field.isSupportedBy(this);
358 }
359
360 /**
361 * Gets the range of valid values for the specified field.
362 * <p>
363 * The range object expresses the minimum and maximum valid values for a field.
364 * This year is used to enhance the accuracy of the returned range.
365 * If it is not possible to return the range, because the field is not supported
366 * or for some other reason, an exception is thrown.
367 * <p>
368 * If the field is a {@link ChronoField} then the query is implemented here.
369 * The {@link #isSupported(TemporalField) supported fields} will return
370 * appropriate range instances.
371 * All other {@code ChronoField} instances will throw a {@code DateTimeException}.
372 * <p>
373 * If the field is not a {@code ChronoField}, then the result of this method
374 * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
375 * passing {@code this} as the argument.
376 * Whether the range can be obtained is determined by the field.
377 *
378 * @param field the field to query the range for, not null
379 * @return the range of valid values for the field, not null
380 * @throws DateTimeException if the range for the field cannot be obtained
381 */
382 @Override
383 public ValueRange range(TemporalField field) {
384 if (field == YEAR_OF_ERA) {
385 return (year <= 0 ? ValueRange.of(1, MAX_VALUE + 1) : ValueRange.of(1, MAX_VALUE));
386 }
387 return Temporal.super.range(field);
388 }
389
390 /**
391 * Gets the value of the specified field from this year as an {@code int}.
392 * <p>
393 * This queries this year for the value for the specified field.
394 * The returned value will always be within the valid range of values for the field.
395 * If it is not possible to return the value, because the field is not supported
396 * or for some other reason, an exception is thrown.
397 * <p>
398 * If the field is a {@link ChronoField} then the query is implemented here.
399 * The {@link #isSupported(TemporalField) supported fields} will return valid
400 * values based on this year.
401 * All other {@code ChronoField} instances will throw a {@code DateTimeException}.
402 * <p>
403 * If the field is not a {@code ChronoField}, then the result of this method
404 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
405 * passing {@code this} as the argument. Whether the value can be obtained,
406 * and what the value represents, is determined by the field.
407 *
408 * @param field the field to get, not null
409 * @return the value for the field
410 * @throws DateTimeException if a value for the field cannot be obtained
411 * @throws ArithmeticException if numeric overflow occurs
412 */
413 @Override // override for Javadoc
414 public int get(TemporalField field) {
415 return range(field).checkValidIntValue(getLong(field), field);
416 }
417
418 /**
419 * Gets the value of the specified field from this year as a {@code long}.
420 * <p>
421 * This queries this year for the value for the specified field.
422 * If it is not possible to return the value, because the field is not supported
423 * or for some other reason, an exception is thrown.
424 * <p>
425 * If the field is a {@link ChronoField} then the query is implemented here.
426 * The {@link #isSupported(TemporalField) supported fields} will return valid
427 * values based on this year.
428 * All other {@code ChronoField} instances will throw a {@code DateTimeException}.
429 * <p>
430 * If the field is not a {@code ChronoField}, then the result of this method
431 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
432 * passing {@code this} as the argument. Whether the value can be obtained,
433 * and what the value represents, is determined by the field.
434 *
435 * @param field the field to get, not null
436 * @return the value for the field
437 * @throws DateTimeException if a value for the field cannot be obtained
438 * @throws ArithmeticException if numeric overflow occurs
439 */
440 @Override
441 public long getLong(TemporalField field) {
442 if (field instanceof ChronoField) {
443 switch ((ChronoField) field) {
444 case YEAR_OF_ERA: return (year < 1 ? 1 - year : year);
445 case YEAR: return year;
446 case ERA: return (year < 1 ? 0 : 1);
447 }
448 throw new DateTimeException("Unsupported field: " + field.getName());
449 }
450 return field.getFrom(this);
451 }
452
453 //-----------------------------------------------------------------------
454 /**
455 * Checks if the year is a leap year, according to the ISO proleptic
456 * calendar system rules.
457 * <p>
458 * This method applies the current rules for leap years across the whole time-line.
459 * In general, a year is a leap year if it is divisible by four without
460 * remainder. However, years divisible by 100, are not leap years, with
461 * the exception of years divisible by 400 which are.
462 * <p>
463 * For example, 1904 is a leap year it is divisible by 4.
464 * 1900 was not a leap year as it is divisible by 100, however 2000 was a
465 * leap year as it is divisible by 400.
466 * <p>
467 * The calculation is proleptic - applying the same rules into the far future and far past.
468 * This is historically inaccurate, but is correct for the ISO-8601 standard.
469 *
470 * @return true if the year is leap, false otherwise
471 */
472 public boolean isLeap() {
473 return Year.isLeap(year);
474 }
475
476 /**
477 * Checks if the month-day is valid for this year.
478 * <p>
479 * This method checks whether this year and the input month and day form
480 * a valid date.
481 *
482 * @param monthDay the month-day to validate, null returns false
483 * @return true if the month and day are valid for this year
484 */
485 public boolean isValidMonthDay(MonthDay monthDay) {
486 return monthDay != null && monthDay.isValidYear(year);
487 }
488
489 /**
490 * Gets the length of this year in days.
491 *
492 * @return the length of this year in days, 365 or 366
493 */
494 public int length() {
495 return isLeap() ? 366 : 365;
496 }
497
498 //-----------------------------------------------------------------------
499 /**
500 * Returns an adjusted copy of this year.
501 * <p>
502 * This returns a {@code Year}, based on this one, with the year adjusted.
503 * The adjustment takes place using the specified adjuster strategy object.
504 * Read the documentation of the adjuster to understand what adjustment will be made.
505 * <p>
506 * The result of this method is obtained by invoking the
507 * {@link TemporalAdjuster#adjustInto(Temporal)} method on the
508 * specified adjuster passing {@code this} as the argument.
509 * <p>
510 * This instance is immutable and unaffected by this method call.
511 *
512 * @param adjuster the adjuster to use, not null
513 * @return a {@code Year} based on {@code this} with the adjustment made, not null
514 * @throws DateTimeException if the adjustment cannot be made
515 * @throws ArithmeticException if numeric overflow occurs
516 */
517 @Override
518 public Year with(TemporalAdjuster adjuster) {
519 return (Year) adjuster.adjustInto(this);
520 }
521
522 /**
523 * Returns a copy of this year with the specified field set to a new value.
524 * <p>
525 * This returns a {@code Year}, based on this one, with the value
526 * for the specified field changed.
527 * If it is not possible to set the value, because the field is not supported or for
528 * some other reason, an exception is thrown.
529 * <p>
530 * If the field is a {@link ChronoField} then the adjustment is implemented here.
531 * The supported fields behave as follows:
532 * <ul>
533 * <li>{@code YEAR_OF_ERA} -
534 * Returns a {@code Year} with the specified year-of-era
535 * The era will be unchanged.
536 * <li>{@code YEAR} -
537 * Returns a {@code Year} with the specified year.
538 * This completely replaces the date and is equivalent to {@link #of(int)}.
539 * <li>{@code ERA} -
540 * Returns a {@code Year} with the specified era.
541 * The year-of-era will be unchanged.
542 * </ul>
543 * <p>
544 * In all cases, if the new value is outside the valid range of values for the field
545 * then a {@code DateTimeException} will be thrown.
546 * <p>
547 * All other {@code ChronoField} instances will throw a {@code DateTimeException}.
548 * <p>
549 * If the field is not a {@code ChronoField}, then the result of this method
550 * is obtained by invoking {@code TemporalField.adjustInto(Temporal, long)}
551 * passing {@code this} as the argument. In this case, the field determines
552 * whether and how to adjust the instant.
553 * <p>
554 * This instance is immutable and unaffected by this method call.
555 *
556 * @param field the field to set in the result, not null
557 * @param newValue the new value of the field in the result
558 * @return a {@code Year} based on {@code this} with the specified field set, not null
559 * @throws DateTimeException if the field cannot be set
560 * @throws ArithmeticException if numeric overflow occurs
561 */
562 @Override
563 public Year with(TemporalField field, long newValue) {
564 if (field instanceof ChronoField) {
565 ChronoField f = (ChronoField) field;
566 f.checkValidValue(newValue);
567 switch (f) {
568 case YEAR_OF_ERA: return Year.of((int) (year < 1 ? 1 - newValue : newValue));
569 case YEAR: return Year.of((int) newValue);
570 case ERA: return (getLong(ERA) == newValue ? this : Year.of(1 - year));
571 }
572 throw new DateTimeException("Unsupported field: " + field.getName());
573 }
574 return field.adjustInto(this, newValue);
575 }
576
577 //-----------------------------------------------------------------------
578 /**
579 * Returns a copy of this year with the specified amount added.
580 * <p>
581 * This returns a {@code Year}, based on this one, with the specified amount added.
582 * The amount is typically {@link Period} but may be any other type implementing
583 * the {@link TemporalAmount} interface.
584 * <p>
585 * The calculation is delegated to the amount object by calling
586 * {@link TemporalAmount#addTo(Temporal)}. The amount implementation is free
587 * to implement the addition in any way it wishes, however it typically
588 * calls back to {@link #plus(long, TemporalUnit)}. Consult the documentation
589 * of the amount implementation to determine if it can be successfully added.
590 * <p>
591 * This instance is immutable and unaffected by this method call.
592 *
593 * @param amountToAdd the amount to add, not null
594 * @return a {@code Year} based on this year with the addition made, not null
595 * @throws DateTimeException if the addition cannot be made
596 * @throws ArithmeticException if numeric overflow occurs
597 */
598 @Override
599 public Year plus(TemporalAmount amountToAdd) {
600 return (Year) amountToAdd.addTo(this);
601 }
602
603 /**
604 * Returns a copy of this year with the specified amount added.
605 * <p>
606 * This returns a {@code Year}, based on this one, with the amount
607 * in terms of the unit added. If it is not possible to add the amount, because the
608 * unit is not supported or for some other reason, an exception is thrown.
609 * <p>
610 * If the field is a {@link ChronoUnit} then the addition is implemented here.
611 * The supported fields behave as follows:
612 * <ul>
613 * <li>{@code YEARS} -
614 * Returns a {@code Year} with the specified number of years added.
615 * This is equivalent to {@link #plusYears(long)}.
616 * <li>{@code DECADES} -
617 * Returns a {@code Year} with the specified number of decades added.
618 * This is equivalent to calling {@link #plusYears(long)} with the amount
619 * multiplied by 10.
620 * <li>{@code CENTURIES} -
621 * Returns a {@code Year} with the specified number of centuries added.
622 * This is equivalent to calling {@link #plusYears(long)} with the amount
623 * multiplied by 100.
624 * <li>{@code MILLENNIA} -
625 * Returns a {@code Year} with the specified number of millennia added.
626 * This is equivalent to calling {@link #plusYears(long)} with the amount
627 * multiplied by 1,000.
628 * <li>{@code ERAS} -
629 * Returns a {@code Year} with the specified number of eras added.
630 * Only two eras are supported so the amount must be one, zero or minus one.
631 * If the amount is non-zero then the year is changed such that the year-of-era
632 * is unchanged.
633 * </ul>
634 * <p>
635 * All other {@code ChronoUnit} instances will throw a {@code DateTimeException}.
636 * <p>
637 * If the field is not a {@code ChronoUnit}, then the result of this method
638 * is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)}
639 * passing {@code this} as the argument. In this case, the unit determines
640 * whether and how to perform the addition.
641 * <p>
642 * This instance is immutable and unaffected by this method call.
643 *
644 * @param amountToAdd the amount of the unit to add to the result, may be negative
645 * @param unit the unit of the amount to add, not null
646 * @return a {@code Year} based on this year with the specified amount added, not null
647 * @throws DateTimeException if the addition cannot be made
648 * @throws ArithmeticException if numeric overflow occurs
649 */
650 @Override
651 public Year plus(long amountToAdd, TemporalUnit unit) {
652 if (unit instanceof ChronoUnit) {
653 switch ((ChronoUnit) unit) {
654 case YEARS: return plusYears(amountToAdd);
655 case DECADES: return plusYears(Math.multiplyExact(amountToAdd, 10));
656 case CENTURIES: return plusYears(Math.multiplyExact(amountToAdd, 100));
657 case MILLENNIA: return plusYears(Math.multiplyExact(amountToAdd, 1000));
658 case ERAS: return with(ERA, Math.addExact(getLong(ERA), amountToAdd));
659 }
660 throw new DateTimeException("Unsupported unit: " + unit.getName());
661 }
662 return unit.addTo(this, amountToAdd);
663 }
664
665 /**
666 * Returns a copy of this year with the specified number of years added.
667 * <p>
668 * This instance is immutable and unaffected by this method call.
669 *
670 * @param yearsToAdd the years to add, may be negative
671 * @return a {@code Year} based on this year with the period added, not null
672 * @throws DateTimeException if the result exceeds the supported year range
673 */
674 public Year plusYears(long yearsToAdd) {
675 if (yearsToAdd == 0) {
676 return this;
677 }
678 return of(YEAR.checkValidIntValue(year + yearsToAdd)); // overflow safe
679 }
680
681 //-----------------------------------------------------------------------
682 /**
683 * Returns a copy of this year with the specified amount subtracted.
684 * <p>
685 * This returns a {@code Year}, based on this one, with the specified amount subtracted.
686 * The amount is typically {@link Period} but may be any other type implementing
687 * the {@link TemporalAmount} interface.
688 * <p>
689 * The calculation is delegated to the amount object by calling
690 * {@link TemporalAmount#subtractFrom(Temporal)}. The amount implementation is free
691 * to implement the subtraction in any way it wishes, however it typically
692 * calls back to {@link #minus(long, TemporalUnit)}. Consult the documentation
693 * of the amount implementation to determine if it can be successfully subtracted.
694 * <p>
695 * This instance is immutable and unaffected by this method call.
696 *
697 * @param amountToSubtract the amount to subtract, not null
698 * @return a {@code Year} based on this year with the subtraction made, not null
699 * @throws DateTimeException if the subtraction cannot be made
700 * @throws ArithmeticException if numeric overflow occurs
701 */
702 @Override
703 public Year minus(TemporalAmount amountToSubtract) {
704 return (Year) amountToSubtract.subtractFrom(this);
705 }
706
707 /**
708 * Returns a copy of this year-month with the specified amount subtracted.
709 * <p>
710 * This returns a {@code YearMonth}, based on this one, with the amount
711 * in terms of the unit subtracted. If it is not possible to subtract the amount,
712 * because the unit is not supported or for some other reason, an exception is thrown.
713 * <p>
714 * This method is equivalent to {@link #plus(long, TemporalUnit)} with the amount negated.
715 * See that method for a full description of how addition, and thus subtraction, works.
716 * <p>
717 * This instance is immutable and unaffected by this method call.
718 *
719 * @param amountToSubtract the amount of the unit to subtract from the result, may be negative
720 * @param unit the unit of the amount to subtract, not null
721 * @return a {@code YearMonth} based on this year-month with the specified amount subtracted, not null
722 * @throws DateTimeException if the subtraction cannot be made
723 * @throws ArithmeticException if numeric overflow occurs
724 */
725 @Override
726 public Year minus(long amountToSubtract, TemporalUnit unit) {
727 return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
728 }
729
730 /**
731 * Returns a copy of this year with the specified number of years subtracted.
732 * <p>
733 * This instance is immutable and unaffected by this method call.
734 *
735 * @param yearsToSubtract the years to subtract, may be negative
736 * @return a {@code Year} based on this year with the period subtracted, not null
737 * @throws DateTimeException if the result exceeds the supported year range
738 */
739 public Year minusYears(long yearsToSubtract) {
740 return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract));
741 }
742
743 //-----------------------------------------------------------------------
744 /**
745 * Queries this year using the specified query.
746 * <p>
747 * This queries this year using the specified query strategy object.
748 * The {@code TemporalQuery} object defines the logic to be used to
749 * obtain the result. Read the documentation of the query to understand
750 * what the result of this method will be.
751 * <p>
752 * The result of this method is obtained by invoking the
753 * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
754 * specified query passing {@code this} as the argument.
755 *
756 * @param <R> the type of the result
757 * @param query the query to invoke, not null
758 * @return the query result, null may be returned (defined by the query)
759 * @throws DateTimeException if unable to query (defined by the query)
760 * @throws ArithmeticException if numeric overflow occurs (defined by the query)
761 */
762 @SuppressWarnings("unchecked")
763 @Override
764 public <R> R query(TemporalQuery<R> query) {
765 if (query == Queries.chronology()) {
766 return (R) IsoChronology.INSTANCE;
767 } else if (query == Queries.precision()) {
768 return (R) YEARS;
769 }
770 return Temporal.super.query(query);
771 }
772
773 /**
774 * Adjusts the specified temporal object to have this year.
775 * <p>
776 * This returns a temporal object of the same observable type as the input
777 * with the year changed to be the same as this.
778 * <p>
779 * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
780 * passing {@link ChronoField#YEAR} as the field.
781 * If the specified temporal object does not use the ISO calendar system then
782 * a {@code DateTimeException} is thrown.
783 * <p>
784 * In most cases, it is clearer to reverse the calling pattern by using
785 * {@link Temporal#with(TemporalAdjuster)}:
786 * <pre>
787 * // these two lines are equivalent, but the second approach is recommended
788 * temporal = thisYear.adjustInto(temporal);
789 * temporal = temporal.with(thisYear);
790 * </pre>
791 * <p>
792 * This instance is immutable and unaffected by this method call.
793 *
794 * @param temporal the target object to be adjusted, not null
795 * @return the adjusted object, not null
796 * @throws DateTimeException if unable to make the adjustment
797 * @throws ArithmeticException if numeric overflow occurs
798 */
799 @Override
800 public Temporal adjustInto(Temporal temporal) {
801 if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) {
802 throw new DateTimeException("Adjustment only supported on ISO date-time");
803 }
804 return temporal.with(YEAR, year);
805 }
806
807 /**
808 * Calculates the period between this year and another year in
809 * terms of the specified unit.
810 * <p>
811 * This calculates the period between two years in terms of a single unit.
812 * The start and end points are {@code this} and the specified year.
813 * The result will be negative if the end is before the start.
814 * The {@code Temporal} passed to this method must be a {@code Year}.
815 * For example, the period in decades between two year can be calculated
816 * using {@code startYear.periodUntil(endYear, DECADES)}.
817 * <p>
818 * The calculation returns a whole number, representing the number of
819 * complete units between the two years.
820 * For example, the period in decades between 2012 and 2031
821 * will only be one decade as it is one year short of two decades.
822 * <p>
823 * There are two equivalent ways of using this method.
824 * The first is to invoke this method.
825 * The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:
826 * <pre>
827 * // these two lines are equivalent
828 * amount = start.periodUntil(end, YEARS);
829 * amount = YEARS.between(start, end);
830 * </pre>
831 * The choice should be made based on which makes the code more readable.
832 * <p>
833 * The calculation is implemented in this method for {@link ChronoUnit}.
834 * The units {@code YEARS}, {@code DECADES}, {@code CENTURIES},
835 * {@code MILLENNIA} and {@code ERAS} are supported.
836 * Other {@code ChronoUnit} values will throw an exception.
837 * <p>
838 * If the unit is not a {@code ChronoUnit}, then the result of this method
839 * is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
840 * passing {@code this} as the first argument and the input temporal as
841 * the second argument.
842 * <p>
843 * This instance is immutable and unaffected by this method call.
844 *
845 * @param endYear the end year, which must be a {@code Year}, not null
846 * @param unit the unit to measure the period in, not null
847 * @return the amount of the period between this year and the end year
848 * @throws DateTimeException if the period cannot be calculated
849 * @throws ArithmeticException if numeric overflow occurs
850 */
851 @Override
852 public long periodUntil(Temporal endYear, TemporalUnit unit) {
853 if (endYear instanceof Year == false) {
854 Objects.requireNonNull(endYear, "endYear");
855 throw new DateTimeException("Unable to calculate period between objects of two different types");
856 }
857 Year end = (Year) endYear;
858 if (unit instanceof ChronoUnit) {
859 long yearsUntil = ((long) end.year) - year; // no overflow
860 switch ((ChronoUnit) unit) {
861 case YEARS: return yearsUntil;
862 case DECADES: return yearsUntil / 10;
863 case CENTURIES: return yearsUntil / 100;
864 case MILLENNIA: return yearsUntil / 1000;
865 case ERAS: return end.getLong(ERA) - getLong(ERA);
866 }
867 throw new DateTimeException("Unsupported unit: " + unit.getName());
868 }
869 return unit.between(this, endYear);
870 }
871
872 //-----------------------------------------------------------------------
873 /**
874 * Combines this year with a day-of-year to create a {@code LocalDate}.
875 * <p>
876 * This returns a {@code LocalDate} formed from this year and the specified day-of-year.
877 * <p>
878 * The day-of-year value 366 is only valid in a leap year.
879 *
880 * @param dayOfYear the day-of-year to use, not null
881 * @return the local date formed from this year and the specified date of year, not null
882 * @throws DateTimeException if the day of year is zero or less, 366 or greater or equal
883 * to 366 and this is not a leap year
884 */
885 public LocalDate atDay(int dayOfYear) {
886 return LocalDate.ofYearDay(year, dayOfYear);
887 }
888
889 /**
890 * Combines this year with a month to create a {@code YearMonth}.
891 * <p>
892 * This returns a {@code YearMonth} formed from this year and the specified month.
893 * All possible combinations of year and month are valid.
894 * <p>
895 * This method can be used as part of a chain to produce a date:
896 * <pre>
897 * LocalDate date = year.atMonth(month).atDay(day);
898 * </pre>
899 *
900 * @param month the month-of-year to use, not null
901 * @return the year-month formed from this year and the specified month, not null
902 */
903 public YearMonth atMonth(Month month) {
904 return YearMonth.of(year, month);
905 }
906
907 /**
908 * Combines this year with a month to create a {@code YearMonth}.
909 * <p>
910 * This returns a {@code YearMonth} formed from this year and the specified month.
911 * All possible combinations of year and month are valid.
912 * <p>
913 * This method can be used as part of a chain to produce a date:
914 * <pre>
915 * LocalDate date = year.atMonth(month).atDay(day);
916 * </pre>
917 *
918 * @param month the month-of-year to use, from 1 (January) to 12 (December)
919 * @return the year-month formed from this year and the specified month, not null
920 * @throws DateTimeException if the month is invalid
921 */
922 public YearMonth atMonth(int month) {
923 return YearMonth.of(year, month);
924 }
925
926 /**
927 * Combines this year with a month-day to create a {@code LocalDate}.
928 * <p>
929 * This returns a {@code LocalDate} formed from this year and the specified month-day.
930 * <p>
931 * A month-day of February 29th will be adjusted to February 28th in the resulting
932 * date if the year is not a leap year.
933 *
934 * @param monthDay the month-day to use, not null
935 * @return the local date formed from this year and the specified month-day, not null
936 */
937 public LocalDate atMonthDay(MonthDay monthDay) {
938 return monthDay.atYear(year);
939 }
940
941 //-----------------------------------------------------------------------
942 /**
943 * Compares this year to another year.
944 * <p>
945 * The comparison is based on the value of the year.
946 * It is "consistent with equals", as defined by {@link Comparable}.
947 *
948 * @param other the other year to compare to, not null
949 * @return the comparator value, negative if less, positive if greater
950 */
951 @Override
952 public int compareTo(Year other) {
953 return year - other.year;
954 }
955
956 /**
957 * Is this year after the specified year.
958 *
959 * @param other the other year to compare to, not null
960 * @return true if this is after the specified year
961 */
962 public boolean isAfter(Year other) {
963 return year > other.year;
964 }
965
966 /**
967 * Is this year before the specified year.
968 *
969 * @param other the other year to compare to, not null
970 * @return true if this point is before the specified year
971 */
972 public boolean isBefore(Year other) {
973 return year < other.year;
974 }
975
976 //-----------------------------------------------------------------------
977 /**
978 * Checks if this year is equal to another year.
979 * <p>
980 * The comparison is based on the time-line position of the years.
981 *
982 * @param obj the object to check, null returns false
983 * @return true if this is equal to the other year
984 */
985 @Override
986 public boolean equals(Object obj) {
987 if (this == obj) {
988 return true;
989 }
990 if (obj instanceof Year) {
991 return year == ((Year) obj).year;
992 }
993 return false;
994 }
995
996 /**
997 * A hash code for this year.
998 *
999 * @return a suitable hash code
1000 */
1001 @Override
1002 public int hashCode() {
1003 return year;
1004 }
1005
1006 //-----------------------------------------------------------------------
1007 /**
1008 * Outputs this year as a {@code String}.
1009 *
1010 * @return a string representation of this year, not null
1011 */
1012 @Override
1013 public String toString() {
1014 return Integer.toString(year);
1015 }
1016
1017 /**
1018 * Outputs this year as a {@code String} using the formatter.
1019 * <p>
1020 * This year will be passed to the formatter
1021 * {@link DateTimeFormatter#format(TemporalAccessor) format method}.
1022 *
1023 * @param formatter the formatter to use, not null
1024 * @return the formatted year string, not null
1025 * @throws DateTimeException if an error occurs during printing
1026 */
1027 public String toString(DateTimeFormatter formatter) {
1028 Objects.requireNonNull(formatter, "formatter");
1029 return formatter.format(this);
1030 }
1031
1032 //-----------------------------------------------------------------------
1033 /**
1034 * Writes the object using a
1035 * <a href="../../../serialized-form.html#java.time.temporal.Ser">dedicated serialized form</a>.
1036 * <pre>
1037 * out.writeByte(11); // identifies this as a Year
1038 * out.writeInt(year);
1039 * </pre>
1040 *
1041 * @return the instance of {@code Ser}, not null
1042 */
1043 private Object writeReplace() {
1044 return new Ser(Ser.YEAR_TYPE, this);
1045 }
1046
1047 /**
1048 * Defend against malicious streams.
1049 * @return never
1050 * @throws InvalidObjectException always
1051 */
1052 private Object readResolve() throws ObjectStreamException {
1053 throw new InvalidObjectException("Deserialization via serialization delegate");
1054 }
1055
1056 void writeExternal(DataOutput out) throws IOException {
1057 out.writeInt(year);
1058 }
1059
1060 static Year readExternal(DataInput in) throws IOException {
1061 return Year.of(in.readInt());
1062 }
1063
1064 }