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