1 /*
2 * Copyright (c) 2012, 2020, 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) 2008-2012, 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.ChronoUnit.DAYS;
65 import static java.time.temporal.ChronoUnit.MONTHS;
66 import static java.time.temporal.ChronoUnit.YEARS;
67
68 import java.io.DataInput;
69 import java.io.DataOutput;
70 import java.io.IOException;
71 import java.io.InvalidObjectException;
72 import java.io.ObjectInputStream;
73 import java.io.Serializable;
74 import java.time.chrono.ChronoLocalDate;
75 import java.time.chrono.ChronoPeriod;
76 import java.time.chrono.Chronology;
77 import java.time.chrono.IsoChronology;
78 import java.time.format.DateTimeParseException;
79 import java.time.temporal.ChronoUnit;
80 import java.time.temporal.Temporal;
81 import java.time.temporal.TemporalAccessor;
82 import java.time.temporal.TemporalAmount;
83 import java.time.temporal.TemporalQueries;
84 import java.time.temporal.TemporalUnit;
85 import java.time.temporal.UnsupportedTemporalTypeException;
86 import java.util.List;
87 import java.util.Objects;
88 import java.util.regex.Matcher;
89 import java.util.regex.Pattern;
90
91 /**
92 * A date-based amount of time in the ISO-8601 calendar system,
93 * such as '2 years, 3 months and 4 days'.
94 * <p>
95 * This class models a quantity or amount of time in terms of years, months and days.
96 * See {@link Duration} for the time-based equivalent to this class.
97 * <p>
98 * Durations and periods differ in their treatment of daylight savings time
99 * when added to {@link ZonedDateTime}. A {@code Duration} will add an exact
100 * number of seconds, thus a duration of one day is always exactly 24 hours.
101 * By contrast, a {@code Period} will add a conceptual day, trying to maintain
102 * the local time.
103 * <p>
104 * For example, consider adding a period of one day and a duration of one day to
105 * 18:00 on the evening before a daylight savings gap. The {@code Period} will add
106 * the conceptual day and result in a {@code ZonedDateTime} at 18:00 the following day.
107 * By contrast, the {@code Duration} will add exactly 24 hours, resulting in a
108 * {@code ZonedDateTime} at 19:00 the following day (assuming a one hour DST gap).
109 * <p>
110 * The supported units of a period are {@link ChronoUnit#YEARS YEARS},
111 * {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS}.
112 * All three fields are always present, but may be set to zero.
113 * <p>
114 * The ISO-8601 calendar system is the modern civil calendar system used today
115 * in most of the world. It is equivalent to the proleptic Gregorian calendar
116 * system, in which today's rules for leap years are applied for all time.
117 * <p>
118 * The period is modeled as a directed amount of time, meaning that individual parts of the
119 * period may be negative.
120 * <p>
121 * This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
122 * class; programmers should treat instances that are {@linkplain #equals(Object) equal}
123 * as interchangeable and should not use instances for synchronization, mutexes, or
124 * with {@linkplain java.lang.ref.Reference object references}.
125 *
126 * <div class="preview-block">
127 * <div class="preview-comment">
128 * When preview features are enabled, {@code Period} is a {@linkplain Class#isValue value class}.
129 * Use of value class instances for synchronization, mutexes, or with
130 * {@linkplain java.lang.ref.Reference object references} result in
131 * {@link IdentityException}.
132 * </div>
133 * </div>
134 *
135 * @implSpec
136 * This class is immutable and thread-safe.
137 *
138 * @since 1.8
139 */
140 @jdk.internal.ValueBased
141 @jdk.internal.MigratedValueClass
142 public final class Period
143 implements ChronoPeriod, Serializable {
144
145 /**
146 * A constant for a period of zero.
147 */
148 public static final Period ZERO = new Period(0, 0, 0);
149 /**
150 * Serialization version.
151 */
152 @java.io.Serial
153 private static final long serialVersionUID = -3587258372562876L;
154 /**
155 * The pattern for parsing.
156 */
157 private static final Pattern PATTERN =
158 Pattern.compile("([-+]?)P(?:([-+]?[0-9]+)Y)?(?:([-+]?[0-9]+)M)?(?:([-+]?[0-9]+)W)?(?:([-+]?[0-9]+)D)?", Pattern.CASE_INSENSITIVE);
159
160 /**
161 * The set of supported units.
162 */
163 private static final List<TemporalUnit> SUPPORTED_UNITS = List.of(YEARS, MONTHS, DAYS);
164
165 /**
166 * The number of years.
167 */
168 private final int years;
169 /**
170 * The number of months.
171 */
172 private final int months;
173 /**
174 * The number of days.
175 */
176 private final int days;
177
178 //-----------------------------------------------------------------------
179 /**
180 * Obtains a {@code Period} representing a number of years.
181 * <p>
182 * The resulting period will have the specified years.
183 * The months and days units will be zero.
184 *
185 * @param years the number of years, positive or negative
186 * @return the period of years, not null
187 */
188 public static Period ofYears(int years) {
189 return create(years, 0, 0);
190 }
191
192 /**
193 * Obtains a {@code Period} representing a number of months.
194 * <p>
195 * The resulting period will have the specified months.
196 * The years and days units will be zero.
197 *
198 * @param months the number of months, positive or negative
199 * @return the period of months, not null
200 */
201 public static Period ofMonths(int months) {
202 return create(0, months, 0);
203 }
204
205 /**
206 * Obtains a {@code Period} representing a number of weeks.
207 * <p>
208 * The resulting period will be day-based, with the amount of days
209 * equal to the number of weeks multiplied by 7.
210 * The years and months units will be zero.
211 *
212 * @param weeks the number of weeks, positive or negative
213 * @return the period, with the input weeks converted to days, not null
214 */
215 public static Period ofWeeks(int weeks) {
216 return create(0, 0, Math.multiplyExact(weeks, 7));
217 }
218
219 /**
220 * Obtains a {@code Period} representing a number of days.
221 * <p>
222 * The resulting period will have the specified days.
223 * The years and months units will be zero.
224 *
225 * @param days the number of days, positive or negative
226 * @return the period of days, not null
227 */
228 public static Period ofDays(int days) {
229 return create(0, 0, days);
230 }
231
232 //-----------------------------------------------------------------------
233 /**
234 * Obtains a {@code Period} representing a number of years, months and days.
235 * <p>
236 * This creates an instance based on years, months and days.
237 *
238 * @param years the amount of years, may be negative
239 * @param months the amount of months, may be negative
240 * @param days the amount of days, may be negative
241 * @return the period of years, months and days, not null
242 */
243 public static Period of(int years, int months, int days) {
244 return create(years, months, days);
245 }
246
247 //-----------------------------------------------------------------------
248 /**
249 * Obtains an instance of {@code Period} from a temporal amount.
250 * <p>
251 * This obtains a period based on the specified amount.
252 * A {@code TemporalAmount} represents an amount of time, which may be
253 * date-based or time-based, which this factory extracts to a {@code Period}.
254 * <p>
255 * The conversion loops around the set of units from the amount and uses
256 * the {@link ChronoUnit#YEARS YEARS}, {@link ChronoUnit#MONTHS MONTHS}
257 * and {@link ChronoUnit#DAYS DAYS} units to create a period.
258 * If any other units are found then an exception is thrown.
259 * <p>
260 * If the amount is a {@code ChronoPeriod} then it must use the ISO chronology.
261 *
262 * @param amount the temporal amount to convert, not null
263 * @return the equivalent period, not null
264 * @throws DateTimeException if unable to convert to a {@code Period}
265 * @throws ArithmeticException if the amount of years, months or days exceeds an int
266 */
267 public static Period from(TemporalAmount amount) {
268 if (amount instanceof Period) {
269 return (Period) amount;
270 }
271 if (amount instanceof ChronoPeriod) {
272 if (IsoChronology.INSTANCE.equals(((ChronoPeriod) amount).getChronology()) == false) {
273 throw new DateTimeException("Period requires ISO chronology: " + amount);
274 }
275 }
276 Objects.requireNonNull(amount, "amount");
277 int years = 0;
278 int months = 0;
279 int days = 0;
280 for (TemporalUnit unit : amount.getUnits()) {
281 long unitAmount = amount.get(unit);
282 if (unit == ChronoUnit.YEARS) {
283 years = Math.toIntExact(unitAmount);
284 } else if (unit == ChronoUnit.MONTHS) {
285 months = Math.toIntExact(unitAmount);
286 } else if (unit == ChronoUnit.DAYS) {
287 days = Math.toIntExact(unitAmount);
288 } else {
289 throw new DateTimeException("Unit must be Years, Months or Days, but was " + unit);
290 }
291 }
292 return create(years, months, days);
293 }
294
295 //-----------------------------------------------------------------------
296 /**
297 * Obtains a {@code Period} from a text string such as {@code PnYnMnD}.
298 * <p>
299 * This will parse the string produced by {@code toString()} which is
300 * based on the ISO-8601 period formats {@code PnYnMnD} and {@code PnW}.
301 * <p>
302 * The string starts with an optional sign, denoted by the ASCII negative
303 * or positive symbol. If negative, the whole period is negated.
304 * The ASCII letter "P" is next in upper or lower case.
305 * There are then four sections, each consisting of a number and a suffix.
306 * At least one of the four sections must be present.
307 * The sections have suffixes in ASCII of "Y", "M", "W" and "D" for
308 * years, months, weeks and days, accepted in upper or lower case.
309 * The suffixes must occur in order.
310 * The number part of each section must consist of ASCII digits.
311 * The number may be prefixed by the ASCII negative or positive symbol.
312 * The number must parse to an {@code int}.
313 * <p>
314 * The leading plus/minus sign, and negative values for other units are
315 * not part of the ISO-8601 standard. In addition, ISO-8601 does not
316 * permit mixing between the {@code PnYnMnD} and {@code PnW} formats.
317 * Any week-based input is multiplied by 7 and treated as a number of days.
318 * <p>
319 * For example, the following are valid inputs:
320 * <pre>
321 * "P2Y" -- Period.ofYears(2)
322 * "P3M" -- Period.ofMonths(3)
323 * "P4W" -- Period.ofWeeks(4)
324 * "P5D" -- Period.ofDays(5)
325 * "P1Y2M3D" -- Period.of(1, 2, 3)
326 * "P1Y2M3W4D" -- Period.of(1, 2, 25)
327 * "P-1Y2M" -- Period.of(-1, 2, 0)
328 * "-P1Y2M" -- Period.of(-1, -2, 0)
329 * </pre>
330 *
331 * @param text the text to parse, not null
332 * @return the parsed period, not null
333 * @throws DateTimeParseException if the text cannot be parsed to a period
334 */
335 public static Period parse(CharSequence text) {
336 Objects.requireNonNull(text, "text");
337 Matcher matcher = PATTERN.matcher(text);
338 if (matcher.matches()) {
339 int negate = (charMatch(text, matcher.start(1), matcher.end(1), '-') ? -1 : 1);
340 int yearStart = matcher.start(2), yearEnd = matcher.end(2);
341 int monthStart = matcher.start(3), monthEnd = matcher.end(3);
342 int weekStart = matcher.start(4), weekEnd = matcher.end(4);
343 int dayStart = matcher.start(5), dayEnd = matcher.end(5);
344 if (yearStart >= 0 || monthStart >= 0 || weekStart >= 0 || dayStart >= 0) {
345 try {
346 int years = parseNumber(text, yearStart, yearEnd, negate);
347 int months = parseNumber(text, monthStart, monthEnd, negate);
348 int weeks = parseNumber(text, weekStart, weekEnd, negate);
349 int days = parseNumber(text, dayStart, dayEnd, negate);
350 days = Math.addExact(days, Math.multiplyExact(weeks, 7));
351 return create(years, months, days);
352 } catch (NumberFormatException ex) {
353 throw new DateTimeParseException("Text cannot be parsed to a Period", text, 0, ex);
354 }
355 }
356 }
357 throw new DateTimeParseException("Text cannot be parsed to a Period", text, 0);
358 }
359
360 private static boolean charMatch(CharSequence text, int start, int end, char c) {
361 return (start >= 0 && end == start + 1 && text.charAt(start) == c);
362 }
363
364 private static int parseNumber(CharSequence text, int start, int end, int negate) {
365 if (start < 0 || end < 0) {
366 return 0;
367 }
368 int val = Integer.parseInt(text, start, end, 10);
369 try {
370 return Math.multiplyExact(val, negate);
371 } catch (ArithmeticException ex) {
372 throw new DateTimeParseException("Text cannot be parsed to a Period", text, 0, ex);
373 }
374 }
375
376 //-----------------------------------------------------------------------
377 /**
378 * Obtains a {@code Period} consisting of the number of years, months,
379 * and days between two dates.
380 * <p>
381 * The start date is included, but the end date is not.
382 * The period is calculated by removing complete months, then calculating
383 * the remaining number of days, adjusting to ensure that both have the same sign.
384 * The number of months is then split into years and months based on a 12 month year.
385 * A month is considered if the end day-of-month is greater than or equal to the start day-of-month.
386 * For example, from {@code 2010-01-15} to {@code 2011-03-18} is one year, two months and three days.
387 * <p>
388 * The result of this method can be a negative period if the end is before the start.
389 * The negative sign will be the same in each of year, month and day.
390 *
391 * @param startDateInclusive the start date, inclusive, not null
392 * @param endDateExclusive the end date, exclusive, not null
393 * @return the period between this date and the end date, not null
394 * @see ChronoLocalDate#until(ChronoLocalDate)
395 */
396 public static Period between(LocalDate startDateInclusive, LocalDate endDateExclusive) {
397 return startDateInclusive.until(endDateExclusive);
398 }
399
400 //-----------------------------------------------------------------------
401 /**
402 * Creates an instance.
403 *
404 * @param years the amount
405 * @param months the amount
406 * @param days the amount
407 */
408 private static Period create(int years, int months, int days) {
409 if ((years | months | days) == 0) {
410 return ZERO;
411 }
412 return new Period(years, months, days);
413 }
414
415 /**
416 * Constructor.
417 *
418 * @param years the amount
419 * @param months the amount
420 * @param days the amount
421 */
422 private Period(int years, int months, int days) {
423 this.years = years;
424 this.months = months;
425 this.days = days;
426 }
427
428 //-----------------------------------------------------------------------
429 /**
430 * Gets the value of the requested unit.
431 * <p>
432 * This returns a value for each of the three supported units,
433 * {@link ChronoUnit#YEARS YEARS}, {@link ChronoUnit#MONTHS MONTHS} and
434 * {@link ChronoUnit#DAYS DAYS}.
435 * All other units throw an exception.
436 *
437 * @param unit the {@code TemporalUnit} for which to return the value
438 * @return the long value of the unit
439 * @throws DateTimeException if the unit is not supported
440 * @throws UnsupportedTemporalTypeException if the unit is not supported
441 */
442 @Override
443 public long get(TemporalUnit unit) {
444 if (unit == ChronoUnit.YEARS) {
445 return getYears();
446 } else if (unit == ChronoUnit.MONTHS) {
447 return getMonths();
448 } else if (unit == ChronoUnit.DAYS) {
449 return getDays();
450 } else {
451 throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
452 }
453 }
454
455 /**
456 * Gets the set of units supported by this period.
457 * <p>
458 * The supported units are {@link ChronoUnit#YEARS YEARS},
459 * {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS}.
460 * They are returned in the order years, months, days.
461 * <p>
462 * This set can be used in conjunction with {@link #get(TemporalUnit)}
463 * to access the entire state of the period.
464 *
465 * @return a list containing the years, months and days units, not null
466 */
467 @Override
468 public List<TemporalUnit> getUnits() {
469 return SUPPORTED_UNITS;
470 }
471
472 /**
473 * Gets the chronology of this period, which is the ISO calendar system.
474 * <p>
475 * The {@code Chronology} represents the calendar system in use.
476 * The ISO-8601 calendar system is the modern civil calendar system used today
477 * in most of the world. It is equivalent to the proleptic Gregorian calendar
478 * system, in which today's rules for leap years are applied for all time.
479 *
480 * @return the ISO chronology, not null
481 */
482 @Override
483 public IsoChronology getChronology() {
484 return IsoChronology.INSTANCE;
485 }
486
487 //-----------------------------------------------------------------------
488 /**
489 * Checks if all three units of this period are zero.
490 * <p>
491 * A zero period has the value zero for the years, months and days units.
492 *
493 * @return true if this period is zero-length
494 */
495 public boolean isZero() {
496 return (this == ZERO);
497 }
498
499 /**
500 * Checks if any of the three units of this period are negative.
501 * <p>
502 * This checks whether the years, months or days units are less than zero.
503 *
504 * @return true if any unit of this period is negative
505 */
506 public boolean isNegative() {
507 return years < 0 || months < 0 || days < 0;
508 }
509
510 //-----------------------------------------------------------------------
511 /**
512 * Gets the amount of years of this period.
513 * <p>
514 * This returns the years unit.
515 * <p>
516 * The months unit is not automatically normalized with the years unit.
517 * This means that a period of "15 months" is different to a period
518 * of "1 year and 3 months".
519 *
520 * @return the amount of years of this period, may be negative
521 */
522 public int getYears() {
523 return years;
524 }
525
526 /**
527 * Gets the amount of months of this period.
528 * <p>
529 * This returns the months unit.
530 * <p>
531 * The months unit is not automatically normalized with the years unit.
532 * This means that a period of "15 months" is different to a period
533 * of "1 year and 3 months".
534 *
535 * @return the amount of months of this period, may be negative
536 */
537 public int getMonths() {
538 return months;
539 }
540
541 /**
542 * Gets the amount of days of this period.
543 * <p>
544 * This returns the days unit.
545 *
546 * @return the amount of days of this period, may be negative
547 */
548 public int getDays() {
549 return days;
550 }
551
552 //-----------------------------------------------------------------------
553 /**
554 * Returns a copy of this period with the specified amount of years.
555 * <p>
556 * This sets the amount of the years unit in a copy of this period.
557 * The months and days units are unaffected.
558 * <p>
559 * The months unit is not automatically normalized with the years unit.
560 * This means that a period of "15 months" is different to a period
561 * of "1 year and 3 months".
562 * <p>
563 * This instance is immutable and unaffected by this method call.
564 *
565 * @param years the years to represent, may be negative
566 * @return a {@code Period} based on this period with the requested years, not null
567 */
568 public Period withYears(int years) {
569 if (years == this.years) {
570 return this;
571 }
572 return create(years, months, days);
573 }
574
575 /**
576 * Returns a copy of this period with the specified amount of months.
577 * <p>
578 * This sets the amount of the months unit in a copy of this period.
579 * The years and days units are unaffected.
580 * <p>
581 * The months unit is not automatically normalized with the years unit.
582 * This means that a period of "15 months" is different to a period
583 * of "1 year and 3 months".
584 * <p>
585 * This instance is immutable and unaffected by this method call.
586 *
587 * @param months the months to represent, may be negative
588 * @return a {@code Period} based on this period with the requested months, not null
589 */
590 public Period withMonths(int months) {
591 if (months == this.months) {
592 return this;
593 }
594 return create(years, months, days);
595 }
596
597 /**
598 * Returns a copy of this period with the specified amount of days.
599 * <p>
600 * This sets the amount of the days unit in a copy of this period.
601 * The years and months units are unaffected.
602 * <p>
603 * This instance is immutable and unaffected by this method call.
604 *
605 * @param days the days to represent, may be negative
606 * @return a {@code Period} based on this period with the requested days, not null
607 */
608 public Period withDays(int days) {
609 if (days == this.days) {
610 return this;
611 }
612 return create(years, months, days);
613 }
614
615 //-----------------------------------------------------------------------
616 /**
617 * Returns a copy of this period with the specified period added.
618 * <p>
619 * This operates separately on the years, months and days.
620 * No normalization is performed.
621 * <p>
622 * For example, "1 year, 6 months and 3 days" plus "2 years, 2 months and 2 days"
623 * returns "3 years, 8 months and 5 days".
624 * <p>
625 * The specified amount is typically an instance of {@code Period}.
626 * Other types are interpreted using {@link Period#from(TemporalAmount)}.
627 * <p>
628 * This instance is immutable and unaffected by this method call.
629 *
630 * @param amountToAdd the amount to add, not null
631 * @return a {@code Period} based on this period with the requested period added, not null
632 * @throws DateTimeException if the specified amount has a non-ISO chronology or
633 * contains an invalid unit
634 * @throws ArithmeticException if numeric overflow occurs
635 */
636 public Period plus(TemporalAmount amountToAdd) {
637 Period isoAmount = Period.from(amountToAdd);
638 return create(
639 Math.addExact(years, isoAmount.years),
640 Math.addExact(months, isoAmount.months),
641 Math.addExact(days, isoAmount.days));
642 }
643
644 /**
645 * Returns a copy of this period with the specified years added.
646 * <p>
647 * This adds the amount to the years unit in a copy of this period.
648 * The months and days units are unaffected.
649 * For example, "1 year, 6 months and 3 days" plus 2 years returns "3 years, 6 months and 3 days".
650 * <p>
651 * This instance is immutable and unaffected by this method call.
652 *
653 * @param yearsToAdd the years to add, positive or negative
654 * @return a {@code Period} based on this period with the specified years added, not null
655 * @throws ArithmeticException if numeric overflow occurs
656 */
657 public Period plusYears(long yearsToAdd) {
658 if (yearsToAdd == 0) {
659 return this;
660 }
661 return create(Math.toIntExact(Math.addExact(years, yearsToAdd)), months, days);
662 }
663
664 /**
665 * Returns a copy of this period with the specified months added.
666 * <p>
667 * This adds the amount to the months unit in a copy of this period.
668 * The years and days units are unaffected.
669 * For example, "1 year, 6 months and 3 days" plus 2 months returns "1 year, 8 months and 3 days".
670 * <p>
671 * This instance is immutable and unaffected by this method call.
672 *
673 * @param monthsToAdd the months to add, positive or negative
674 * @return a {@code Period} based on this period with the specified months added, not null
675 * @throws ArithmeticException if numeric overflow occurs
676 */
677 public Period plusMonths(long monthsToAdd) {
678 if (monthsToAdd == 0) {
679 return this;
680 }
681 return create(years, Math.toIntExact(Math.addExact(months, monthsToAdd)), days);
682 }
683
684 /**
685 * Returns a copy of this period with the specified days added.
686 * <p>
687 * This adds the amount to the days unit in a copy of this period.
688 * The years and months units are unaffected.
689 * For example, "1 year, 6 months and 3 days" plus 2 days returns "1 year, 6 months and 5 days".
690 * <p>
691 * This instance is immutable and unaffected by this method call.
692 *
693 * @param daysToAdd the days to add, positive or negative
694 * @return a {@code Period} based on this period with the specified days added, not null
695 * @throws ArithmeticException if numeric overflow occurs
696 */
697 public Period plusDays(long daysToAdd) {
698 if (daysToAdd == 0) {
699 return this;
700 }
701 return create(years, months, Math.toIntExact(Math.addExact(days, daysToAdd)));
702 }
703
704 //-----------------------------------------------------------------------
705 /**
706 * Returns a copy of this period with the specified period subtracted.
707 * <p>
708 * This operates separately on the years, months and days.
709 * No normalization is performed.
710 * <p>
711 * For example, "1 year, 6 months and 3 days" minus "2 years, 2 months and 2 days"
712 * returns "-1 years, 4 months and 1 day".
713 * <p>
714 * The specified amount is typically an instance of {@code Period}.
715 * Other types are interpreted using {@link Period#from(TemporalAmount)}.
716 * <p>
717 * This instance is immutable and unaffected by this method call.
718 *
719 * @param amountToSubtract the amount to subtract, not null
720 * @return a {@code Period} based on this period with the requested period subtracted, not null
721 * @throws DateTimeException if the specified amount has a non-ISO chronology or
722 * contains an invalid unit
723 * @throws ArithmeticException if numeric overflow occurs
724 */
725 public Period minus(TemporalAmount amountToSubtract) {
726 Period isoAmount = Period.from(amountToSubtract);
727 return create(
728 Math.subtractExact(years, isoAmount.years),
729 Math.subtractExact(months, isoAmount.months),
730 Math.subtractExact(days, isoAmount.days));
731 }
732
733 /**
734 * Returns a copy of this period with the specified years subtracted.
735 * <p>
736 * This subtracts the amount from the years unit in a copy of this period.
737 * The months and days units are unaffected.
738 * For example, "1 year, 6 months and 3 days" minus 2 years returns "-1 years, 6 months and 3 days".
739 * <p>
740 * This instance is immutable and unaffected by this method call.
741 *
742 * @param yearsToSubtract the years to subtract, positive or negative
743 * @return a {@code Period} based on this period with the specified years subtracted, not null
744 * @throws ArithmeticException if numeric overflow occurs
745 */
746 public Period minusYears(long yearsToSubtract) {
747 return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract));
748 }
749
750 /**
751 * Returns a copy of this period with the specified months subtracted.
752 * <p>
753 * This subtracts the amount from the months unit in a copy of this period.
754 * The years and days units are unaffected.
755 * For example, "1 year, 6 months and 3 days" minus 2 months returns "1 year, 4 months and 3 days".
756 * <p>
757 * This instance is immutable and unaffected by this method call.
758 *
759 * @param monthsToSubtract the years to subtract, positive or negative
760 * @return a {@code Period} based on this period with the specified months subtracted, not null
761 * @throws ArithmeticException if numeric overflow occurs
762 */
763 public Period minusMonths(long monthsToSubtract) {
764 return (monthsToSubtract == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-monthsToSubtract));
765 }
766
767 /**
768 * Returns a copy of this period with the specified days subtracted.
769 * <p>
770 * This subtracts the amount from the days unit in a copy of this period.
771 * The years and months units are unaffected.
772 * For example, "1 year, 6 months and 3 days" minus 2 days returns "1 year, 6 months and 1 day".
773 * <p>
774 * This instance is immutable and unaffected by this method call.
775 *
776 * @param daysToSubtract the months to subtract, positive or negative
777 * @return a {@code Period} based on this period with the specified days subtracted, not null
778 * @throws ArithmeticException if numeric overflow occurs
779 */
780 public Period minusDays(long daysToSubtract) {
781 return (daysToSubtract == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-daysToSubtract));
782 }
783
784 //-----------------------------------------------------------------------
785 /**
786 * Returns a new instance with each element in this period multiplied
787 * by the specified scalar.
788 * <p>
789 * This returns a period with each of the years, months and days units
790 * individually multiplied.
791 * For example, a period of "2 years, -3 months and 4 days" multiplied by
792 * 3 will return "6 years, -9 months and 12 days".
793 * No normalization is performed.
794 *
795 * @param scalar the scalar to multiply by, not null
796 * @return a {@code Period} based on this period with the amounts multiplied by the scalar, not null
797 * @throws ArithmeticException if numeric overflow occurs
798 */
799 public Period multipliedBy(int scalar) {
800 if (this == ZERO || scalar == 1) {
801 return this;
802 }
803 return create(
804 Math.multiplyExact(years, scalar),
805 Math.multiplyExact(months, scalar),
806 Math.multiplyExact(days, scalar));
807 }
808
809 /**
810 * Returns a new instance with each amount in this period negated.
811 * <p>
812 * This returns a period with each of the years, months and days units
813 * individually negated.
814 * For example, a period of "2 years, -3 months and 4 days" will be
815 * negated to "-2 years, 3 months and -4 days".
816 * No normalization is performed.
817 *
818 * @return a {@code Period} based on this period with the amounts negated, not null
819 * @throws ArithmeticException if numeric overflow occurs, which only happens if
820 * one of the units has the value {@code Integer.MIN_VALUE}
821 */
822 public Period negated() {
823 return multipliedBy(-1);
824 }
825
826 //-----------------------------------------------------------------------
827 /**
828 * Returns a copy of this period with the years and months normalized.
829 * <p>
830 * This normalizes the years and months units, leaving the days unit unchanged.
831 * The months unit is adjusted to have an absolute value less than 12,
832 * with the years unit being adjusted to compensate. For example, a period of
833 * "1 Year and 15 months" will be normalized to "2 years and 3 months".
834 * <p>
835 * The sign of the years and months units will be the same after normalization.
836 * For example, a period of "1 year and -25 months" will be normalized to
837 * "-1 year and -1 month".
838 * <p>
839 * This instance is immutable and unaffected by this method call.
840 *
841 * @return a {@code Period} based on this period with excess months normalized to years, not null
842 * @throws ArithmeticException if numeric overflow occurs
843 */
844 public Period normalized() {
845 long totalMonths = toTotalMonths();
846 long splitYears = totalMonths / 12;
847 int splitMonths = (int) (totalMonths % 12); // no overflow
848 if (splitYears == years && splitMonths == months) {
849 return this;
850 }
851 return create(Math.toIntExact(splitYears), splitMonths, days);
852 }
853
854 /**
855 * Gets the total number of months in this period.
856 * <p>
857 * This returns the total number of months in the period by multiplying the
858 * number of years by 12 and adding the number of months.
859 * <p>
860 * This instance is immutable and unaffected by this method call.
861 *
862 * @return the total number of months in the period, may be negative
863 */
864 public long toTotalMonths() {
865 return years * 12L + months; // no overflow
866 }
867
868 //-------------------------------------------------------------------------
869 /**
870 * Adds this period to the specified temporal object.
871 * <p>
872 * This returns a temporal object of the same observable type as the input
873 * with this period added.
874 * If the temporal has a chronology, it must be the ISO chronology.
875 * <p>
876 * In most cases, it is clearer to reverse the calling pattern by using
877 * {@link Temporal#plus(TemporalAmount)}.
878 * <pre>
879 * // these two lines are equivalent, but the second approach is recommended
880 * dateTime = thisPeriod.addTo(dateTime);
881 * dateTime = dateTime.plus(thisPeriod);
882 * </pre>
883 * <p>
884 * The calculation operates as follows.
885 * First, the chronology of the temporal is checked to ensure it is ISO chronology or null.
886 * Second, if the months are zero, the years are added if non-zero, otherwise
887 * the combination of years and months is added if non-zero.
888 * Finally, any days are added.
889 * <p>
890 * This approach ensures that a partial period can be added to a partial date.
891 * For example, a period of years and/or months can be added to a {@code YearMonth},
892 * but a period including days cannot.
893 * The approach also adds years and months together when necessary, which ensures
894 * correct behaviour at the end of the month.
895 * <p>
896 * This instance is immutable and unaffected by this method call.
897 *
898 * @param temporal the temporal object to adjust, not null
899 * @return an object of the same type with the adjustment made, not null
900 * @throws DateTimeException if unable to add
901 * @throws ArithmeticException if numeric overflow occurs
902 */
903 @Override
904 public Temporal addTo(Temporal temporal) {
905 validateChrono(temporal);
906 if (months == 0) {
907 if (years != 0) {
908 temporal = temporal.plus(years, YEARS);
909 }
910 } else {
911 long totalMonths = toTotalMonths();
912 if (totalMonths != 0) {
913 temporal = temporal.plus(totalMonths, MONTHS);
914 }
915 }
916 if (days != 0) {
917 temporal = temporal.plus(days, DAYS);
918 }
919 return temporal;
920 }
921
922 /**
923 * Subtracts this period from the specified temporal object.
924 * <p>
925 * This returns a temporal object of the same observable type as the input
926 * with this period subtracted.
927 * If the temporal has a chronology, it must be the ISO chronology.
928 * <p>
929 * In most cases, it is clearer to reverse the calling pattern by using
930 * {@link Temporal#minus(TemporalAmount)}.
931 * <pre>
932 * // these two lines are equivalent, but the second approach is recommended
933 * dateTime = thisPeriod.subtractFrom(dateTime);
934 * dateTime = dateTime.minus(thisPeriod);
935 * </pre>
936 * <p>
937 * The calculation operates as follows.
938 * First, the chronology of the temporal is checked to ensure it is ISO chronology or null.
939 * Second, if the months are zero, the years are subtracted if non-zero, otherwise
940 * the combination of years and months is subtracted if non-zero.
941 * Finally, any days are subtracted.
942 * <p>
943 * This approach ensures that a partial period can be subtracted from a partial date.
944 * For example, a period of years and/or months can be subtracted from a {@code YearMonth},
945 * but a period including days cannot.
946 * The approach also subtracts years and months together when necessary, which ensures
947 * correct behaviour at the end of the month.
948 * <p>
949 * This instance is immutable and unaffected by this method call.
950 *
951 * @param temporal the temporal object to adjust, not null
952 * @return an object of the same type with the adjustment made, not null
953 * @throws DateTimeException if unable to subtract
954 * @throws ArithmeticException if numeric overflow occurs
955 */
956 @Override
957 public Temporal subtractFrom(Temporal temporal) {
958 validateChrono(temporal);
959 if (months == 0) {
960 if (years != 0) {
961 temporal = temporal.minus(years, YEARS);
962 }
963 } else {
964 long totalMonths = toTotalMonths();
965 if (totalMonths != 0) {
966 temporal = temporal.minus(totalMonths, MONTHS);
967 }
968 }
969 if (days != 0) {
970 temporal = temporal.minus(days, DAYS);
971 }
972 return temporal;
973 }
974
975 /**
976 * Validates that the temporal has the correct chronology.
977 */
978 private void validateChrono(TemporalAccessor temporal) {
979 Objects.requireNonNull(temporal, "temporal");
980 Chronology temporalChrono = temporal.query(TemporalQueries.chronology());
981 if (temporalChrono != null && IsoChronology.INSTANCE.equals(temporalChrono) == false) {
982 throw new DateTimeException("Chronology mismatch, expected: ISO, actual: " + temporalChrono.getId());
983 }
984 }
985
986 //-----------------------------------------------------------------------
987 /**
988 * Checks if this period is equal to another period.
989 * <p>
990 * The comparison is based on the type {@code Period} and each of the three amounts.
991 * To be equal, the years, months and days units must be individually equal.
992 * Note that this means that a period of "15 Months" is not equal to a period
993 * of "1 Year and 3 Months".
994 *
995 * @param obj the object to check, null returns false
996 * @return true if this is equal to the other period
997 */
998 @Override
999 public boolean equals(Object obj) {
1000 if (this == obj) {
1001 return true;
1002 }
1003 return (obj instanceof Period other)
1004 && years == other.years
1005 && months == other.months
1006 && days == other.days;
1007 }
1008
1009 /**
1010 * A hash code for this period.
1011 *
1012 * @return a suitable hash code
1013 */
1014 @Override
1015 public int hashCode() {
1016 return years + Integer.rotateLeft(months, 8) + Integer.rotateLeft(days, 16);
1017 }
1018
1019 //-----------------------------------------------------------------------
1020 /**
1021 * Outputs this period as a {@code String}, such as {@code P6Y3M1D}.
1022 * <p>
1023 * The output will be in the ISO-8601 period format.
1024 * A zero period will be represented as zero days, 'P0D'.
1025 *
1026 * @return a string representation of this period, not null
1027 */
1028 @Override
1029 public String toString() {
1030 if (this == ZERO) {
1031 return "P0D";
1032 } else {
1033 StringBuilder buf = new StringBuilder();
1034 buf.append('P');
1035 if (years != 0) {
1036 buf.append(years).append('Y');
1037 }
1038 if (months != 0) {
1039 buf.append(months).append('M');
1040 }
1041 if (days != 0) {
1042 buf.append(days).append('D');
1043 }
1044 return buf.toString();
1045 }
1046 }
1047
1048 //-----------------------------------------------------------------------
1049 /**
1050 * Writes the object using a
1051 * <a href="{@docRoot}/serialized-form.html#java.time.Ser">dedicated serialized form</a>.
1052 * @serialData
1053 * <pre>
1054 * out.writeByte(14); // identifies a Period
1055 * out.writeInt(years);
1056 * out.writeInt(months);
1057 * out.writeInt(days);
1058 * </pre>
1059 *
1060 * @return the instance of {@code Ser}, not null
1061 */
1062 @java.io.Serial
1063 private Object writeReplace() {
1064 return new Ser(Ser.PERIOD_TYPE, this);
1065 }
1066
1067 /**
1068 * Defend against malicious streams.
1069 *
1070 * @param s the stream to read
1071 * @throws java.io.InvalidObjectException always
1072 */
1073 @java.io.Serial
1074 private void readObject(ObjectInputStream s) throws InvalidObjectException {
1075 throw new InvalidObjectException("Deserialization via serialization delegate");
1076 }
1077
1078 void writeExternal(DataOutput out) throws IOException {
1079 out.writeInt(years);
1080 out.writeInt(months);
1081 out.writeInt(days);
1082 }
1083
1084 static Period readExternal(DataInput in) throws IOException {
1085 int years = in.readInt();
1086 int months = in.readInt();
1087 int days = in.readInt();
1088 return Period.of(years, months, days);
1089 }
1090
1091 }