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) 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.Arrays;
87 import java.util.Collections;
88 import java.util.List;
89 import java.util.Objects;
90 import java.util.regex.Matcher;
91 import java.util.regex.Pattern;
92
93 /**
94 * A date-based amount of time in the ISO-8601 calendar system,
95 * such as '2 years, 3 months and 4 days'.
96 * <p>
97 * This class models a quantity or amount of time in terms of years, months and days.
98 * See {@link Duration} for the time-based equivalent to this class.
99 * <p>
100 * Durations and periods differ in their treatment of daylight savings time
101 * when added to {@link ZonedDateTime}. A {@code Duration} will add an exact
102 * number of seconds, thus a duration of one day is always exactly 24 hours.
103 * By contrast, a {@code Period} will add a conceptual day, trying to maintain
104 * the local time.
105 * <p>
106 * For example, consider adding a period of one day and a duration of one day to
107 * 18:00 on the evening before a daylight savings gap. The {@code Period} will add
108 * the conceptual day and result in a {@code ZonedDateTime} at 18:00 the following day.
109 * By contrast, the {@code Duration} will add exactly 24 hours, resulting in a
110 * {@code ZonedDateTime} at 19:00 the following day (assuming a one hour DST gap).
111 * <p>
112 * The supported units of a period are {@link ChronoUnit#YEARS YEARS},
113 * {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS}.
114 * All three fields are always present, but may be set to zero.
115 * <p>
116 * The ISO-8601 calendar system is the modern civil calendar system used today
117 * in most of the world. It is equivalent to the proleptic Gregorian calendar
118 * system, in which today's rules for leap years are applied for all time.
119 * <p>
120 * The period is modeled as a directed amount of time, meaning that individual parts of the
121 * period may be negative.
122 *
123 * <p>
124 * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
125 * class; use of identity-sensitive operations (including reference equality
126 * ({@code ==}), identity hash code, or synchronization) on instances of
127 * {@code Period} may have unpredictable results and should be avoided.
128 * The {@code equals} method should be used for comparisons.
129 *
130 * @implSpec
131 * This class is immutable and thread-safe.
132 *
133 * @since 1.8
134 */
135 public final class Period
136 implements ChronoPeriod, Serializable {
137
138 /**
139 * A constant for a period of zero.
140 */
141 public static final Period ZERO = new Period(0, 0, 0);
142 /**
143 * Serialization version.
144 */
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 =
156 Collections.unmodifiableList(Arrays.<TemporalUnit>asList(YEARS, MONTHS, DAYS));
157
158 /**
159 * The number of years.
160 */
161 private final int years;
162 /**
163 * The number of months.
164 */
165 private final int months;
166 /**
167 * The number of days.
168 */
169 private final int days;
170
171 //-----------------------------------------------------------------------
172 /**
173 * Obtains a {@code Period} representing a number of years.
174 * <p>
175 * The resulting period will have the specified years.
176 * The months and days units will be zero.
177 *
178 * @param years the number of years, positive or negative
179 * @return the period of years, not null
180 */
181 public static Period ofYears(int years) {
182 return create(years, 0, 0);
183 }
184
185 /**
186 * Obtains a {@code Period} representing a number of months.
187 * <p>
188 * The resulting period will have the specified months.
189 * The years and days units will be zero.
190 *
191 * @param months the number of months, positive or negative
192 * @return the period of months, not null
193 */
194 public static Period ofMonths(int months) {
195 return create(0, months, 0);
196 }
197
198 /**
199 * Obtains a {@code Period} representing a number of weeks.
200 * <p>
201 * The resulting period will be day-based, with the amount of days
202 * equal to the number of weeks multiplied by 7.
203 * The years and months units will be zero.
204 *
205 * @param weeks the number of weeks, positive or negative
206 * @return the period, with the input weeks converted to days, not null
207 */
208 public static Period ofWeeks(int weeks) {
209 return create(0, 0, Math.multiplyExact(weeks, 7));
210 }
211
212 /**
213 * Obtains a {@code Period} representing a number of days.
214 * <p>
215 * The resulting period will have the specified days.
216 * The years and months units will be zero.
217 *
218 * @param days the number of days, positive or negative
219 * @return the period of days, not null
220 */
221 public static Period ofDays(int days) {
222 return create(0, 0, days);
223 }
224
225 //-----------------------------------------------------------------------
226 /**
227 * Obtains a {@code Period} representing a number of years, months and days.
228 * <p>
229 * This creates an instance based on years, months and days.
230 *
231 * @param years the amount of years, may be negative
232 * @param months the amount of months, may be negative
233 * @param days the amount of days, may be negative
234 * @return the period of years, months and days, not null
235 */
236 public static Period of(int years, int months, int days) {
237 return create(years, months, days);
238 }
239
240 //-----------------------------------------------------------------------
241 /**
242 * Obtains an instance of {@code Period} from a temporal amount.
243 * <p>
244 * This obtains a period based on the specified amount.
245 * A {@code TemporalAmount} represents an amount of time, which may be
246 * date-based or time-based, which this factory extracts to a {@code Period}.
247 * <p>
248 * The conversion loops around the set of units from the amount and uses
249 * the {@link ChronoUnit#YEARS YEARS}, {@link ChronoUnit#MONTHS MONTHS}
250 * and {@link ChronoUnit#DAYS DAYS} units to create a period.
251 * If any other units are found then an exception is thrown.
252 * <p>
253 * If the amount is a {@code ChronoPeriod} then it must use the ISO chronology.
254 *
255 * @param amount the temporal amount to convert, not null
256 * @return the equivalent period, not null
257 * @throws DateTimeException if unable to convert to a {@code Period}
258 * @throws ArithmeticException if the amount of years, months or days exceeds an int
259 */
260 public static Period from(TemporalAmount amount) {
261 if (amount instanceof Period) {
262 return (Period) amount;
263 }
264 if (amount instanceof ChronoPeriod) {
265 if (IsoChronology.INSTANCE.equals(((ChronoPeriod) amount).getChronology()) == false) {
266 throw new DateTimeException("Period requires ISO chronology: " + amount);
267 }
268 }
269 Objects.requireNonNull(amount, "amount");
270 int years = 0;
271 int months = 0;
272 int days = 0;
273 for (TemporalUnit unit : amount.getUnits()) {
274 long unitAmount = amount.get(unit);
275 if (unit == ChronoUnit.YEARS) {
276 years = Math.toIntExact(unitAmount);
277 } else if (unit == ChronoUnit.MONTHS) {
278 months = Math.toIntExact(unitAmount);
279 } else if (unit == ChronoUnit.DAYS) {
280 days = Math.toIntExact(unitAmount);
281 } else {
282 throw new DateTimeException("Unit must be Years, Months or Days, but was " + unit);
283 }
284 }
285 return create(years, months, days);
286 }
287
288 //-----------------------------------------------------------------------
289 /**
290 * Obtains a {@code Period} from a text string such as {@code PnYnMnD}.
291 * <p>
292 * This will parse the string produced by {@code toString()} which is
293 * based on the ISO-8601 period formats {@code PnYnMnD} and {@code PnW}.
294 * <p>
295 * The string starts with an optional sign, denoted by the ASCII negative
296 * or positive symbol. If negative, the whole period is negated.
297 * The ASCII letter "P" is next in upper or lower case.
298 * There are then four sections, each consisting of a number and a suffix.
299 * At least one of the four sections must be present.
300 * The sections have suffixes in ASCII of "Y", "M", "W" and "D" for
301 * years, months, weeks and days, accepted in upper or lower case.
302 * The suffixes must occur in order.
303 * The number part of each section must consist of ASCII digits.
304 * The number may be prefixed by the ASCII negative or positive symbol.
305 * The number must parse to an {@code int}.
306 * <p>
307 * The leading plus/minus sign, and negative values for other units are
308 * not part of the ISO-8601 standard. In addition, ISO-8601 does not
309 * permit mixing between the {@code PnYnMnD} and {@code PnW} formats.
310 * Any week-based input is multiplied by 7 and treated as a number of days.
311 * <p>
312 * For example, the following are valid inputs:
313 * <pre>
314 * "P2Y" -- Period.ofYears(2)
315 * "P3M" -- Period.ofMonths(3)
316 * "P4W" -- Period.ofWeeks(4)
317 * "P5D" -- Period.ofDays(5)
318 * "P1Y2M3D" -- Period.of(1, 2, 3)
319 * "P1Y2M3W4D" -- Period.of(1, 2, 25)
320 * "P-1Y2M" -- Period.of(-1, 2, 0)
321 * "-P1Y2M" -- Period.of(-1, -2, 0)
322 * </pre>
323 *
324 * @param text the text to parse, not null
325 * @return the parsed period, not null
326 * @throws DateTimeParseException if the text cannot be parsed to a period
327 */
328 public static Period parse(CharSequence text) {
329 Objects.requireNonNull(text, "text");
330 Matcher matcher = PATTERN.matcher(text);
331 if (matcher.matches()) {
332 int negate = ("-".equals(matcher.group(1)) ? -1 : 1);
333 String yearMatch = matcher.group(2);
334 String monthMatch = matcher.group(3);
335 String weekMatch = matcher.group(4);
336 String dayMatch = matcher.group(5);
337 if (yearMatch != null || monthMatch != null || dayMatch != null || weekMatch != null) {
338 try {
339 int years = parseNumber(text, yearMatch, negate);
340 int months = parseNumber(text, monthMatch, negate);
341 int weeks = parseNumber(text, weekMatch, negate);
342 int days = parseNumber(text, dayMatch, negate);
343 days = Math.addExact(days, Math.multiplyExact(weeks, 7));
344 return create(years, months, days);
345 } catch (NumberFormatException ex) {
346 throw new DateTimeParseException("Text cannot be parsed to a Period", text, 0, ex);
347 }
348 }
349 }
350 throw new DateTimeParseException("Text cannot be parsed to a Period", text, 0);
351 }
352
353 private static int parseNumber(CharSequence text, String str, int negate) {
354 if (str == null) {
355 return 0;
356 }
357 int val = Integer.parseInt(str);
358 try {
359 return Math.multiplyExact(val, negate);
360 } catch (ArithmeticException ex) {
361 throw new DateTimeParseException("Text cannot be parsed to a Period", text, 0, ex);
362 }
363 }
364
365 //-----------------------------------------------------------------------
366 /**
367 * Obtains a {@code Period} consisting of the number of years, months,
368 * and days between two dates.
369 * <p>
370 * The start date is included, but the end date is not.
371 * The period is calculated by removing complete months, then calculating
372 * the remaining number of days, adjusting to ensure that both have the same sign.
373 * The number of months is then split into years and months based on a 12 month year.
374 * A month is considered if the end day-of-month is greater than or equal to the start day-of-month.
375 * For example, from {@code 2010-01-15} to {@code 2011-03-18} is one year, two months and three days.
376 * <p>
377 * The result of this method can be a negative period if the end is before the start.
378 * The negative sign will be the same in each of year, month and day.
379 *
380 * @param startDateInclusive the start date, inclusive, not null
381 * @param endDateExclusive the end date, exclusive, not null
382 * @return the period between this date and the end date, not null
383 * @see ChronoLocalDate#until(ChronoLocalDate)
384 */
385 public static Period between(LocalDate startDateInclusive, LocalDate endDateExclusive) {
386 return startDateInclusive.until(endDateExclusive);
387 }
388
389 //-----------------------------------------------------------------------
390 /**
391 * Creates an instance.
392 *
393 * @param years the amount
394 * @param months the amount
395 * @param days the amount
396 */
397 private static Period create(int years, int months, int days) {
398 if ((years | months | days) == 0) {
399 return ZERO;
400 }
401 return new Period(years, months, days);
402 }
403
404 /**
405 * Constructor.
406 *
407 * @param years the amount
408 * @param months the amount
409 * @param days the amount
410 */
411 private Period(int years, int months, int days) {
412 this.years = years;
413 this.months = months;
414 this.days = days;
415 }
416
417 //-----------------------------------------------------------------------
418 /**
419 * Gets the value of the requested unit.
420 * <p>
421 * This returns a value for each of the three supported units,
422 * {@link ChronoUnit#YEARS YEARS}, {@link ChronoUnit#MONTHS MONTHS} and
423 * {@link ChronoUnit#DAYS DAYS}.
424 * All other units throw an exception.
425 *
426 * @param unit the {@code TemporalUnit} for which to return the value
427 * @return the long value of the unit
428 * @throws DateTimeException if the unit is not supported
429 * @throws UnsupportedTemporalTypeException if the unit is not supported
430 */
431 @Override
432 public long get(TemporalUnit unit) {
433 if (unit == ChronoUnit.YEARS) {
434 return getYears();
435 } else if (unit == ChronoUnit.MONTHS) {
436 return getMonths();
437 } else if (unit == ChronoUnit.DAYS) {
438 return getDays();
439 } else {
440 throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
441 }
442 }
443
444 /**
445 * Gets the set of units supported by this period.
446 * <p>
447 * The supported units are {@link ChronoUnit#YEARS YEARS},
448 * {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS}.
449 * They are returned in the order years, months, days.
450 * <p>
451 * This set can be used in conjunction with {@link #get(TemporalUnit)}
452 * to access the entire state of the period.
453 *
454 * @return a list containing the years, months and days units, not null
455 */
456 @Override
457 public List<TemporalUnit> getUnits() {
458 return SUPPORTED_UNITS;
459 }
460
461 /**
462 * Gets the chronology of this period, which is the ISO calendar system.
463 * <p>
464 * The {@code Chronology} represents the calendar system in use.
465 * The ISO-8601 calendar system is the modern civil calendar system used today
466 * in most of the world. It is equivalent to the proleptic Gregorian calendar
467 * system, in which today's rules for leap years are applied for all time.
468 *
469 * @return the ISO chronology, not null
470 */
471 @Override
472 public IsoChronology getChronology() {
473 return IsoChronology.INSTANCE;
474 }
475
476 //-----------------------------------------------------------------------
477 /**
478 * Checks if all three units of this period are zero.
479 * <p>
480 * A zero period has the value zero for the years, months and days units.
481 *
482 * @return true if this period is zero-length
483 */
484 public boolean isZero() {
485 return (this == ZERO);
486 }
487
488 /**
489 * Checks if any of the three units of this period are negative.
490 * <p>
491 * This checks whether the years, months or days units are less than zero.
492 *
493 * @return true if any unit of this period is negative
494 */
495 public boolean isNegative() {
496 return years < 0 || months < 0 || days < 0;
497 }
498
499 //-----------------------------------------------------------------------
500 /**
501 * Gets the amount of years of this period.
502 * <p>
503 * This returns the years unit.
504 * <p>
505 * The months unit is not automatically normalized with the years unit.
506 * This means that a period of "15 months" is different to a period
507 * of "1 year and 3 months".
508 *
509 * @return the amount of years of this period, may be negative
510 */
511 public int getYears() {
512 return years;
513 }
514
515 /**
516 * Gets the amount of months of this period.
517 * <p>
518 * This returns the months unit.
519 * <p>
520 * The months unit is not automatically normalized with the years unit.
521 * This means that a period of "15 months" is different to a period
522 * of "1 year and 3 months".
523 *
524 * @return the amount of months of this period, may be negative
525 */
526 public int getMonths() {
527 return months;
528 }
529
530 /**
531 * Gets the amount of days of this period.
532 * <p>
533 * This returns the days unit.
534 *
535 * @return the amount of days of this period, may be negative
536 */
537 public int getDays() {
538 return days;
539 }
540
541 //-----------------------------------------------------------------------
542 /**
543 * Returns a copy of this period with the specified amount of years.
544 * <p>
545 * This sets the amount of the years unit in a copy of this period.
546 * The months and days units are unaffected.
547 * <p>
548 * The months unit is not automatically normalized with the years unit.
549 * This means that a period of "15 months" is different to a period
550 * of "1 year and 3 months".
551 * <p>
552 * This instance is immutable and unaffected by this method call.
553 *
554 * @param years the years to represent, may be negative
555 * @return a {@code Period} based on this period with the requested years, not null
556 */
557 public Period withYears(int years) {
558 if (years == this.years) {
559 return this;
560 }
561 return create(years, months, days);
562 }
563
564 /**
565 * Returns a copy of this period with the specified amount of months.
566 * <p>
567 * This sets the amount of the months unit in a copy of this period.
568 * The years and days units are unaffected.
569 * <p>
570 * The months unit is not automatically normalized with the years unit.
571 * This means that a period of "15 months" is different to a period
572 * of "1 year and 3 months".
573 * <p>
574 * This instance is immutable and unaffected by this method call.
575 *
576 * @param months the months to represent, may be negative
577 * @return a {@code Period} based on this period with the requested months, not null
578 */
579 public Period withMonths(int months) {
580 if (months == this.months) {
581 return this;
582 }
583 return create(years, months, days);
584 }
585
586 /**
587 * Returns a copy of this period with the specified amount of days.
588 * <p>
589 * This sets the amount of the days unit in a copy of this period.
590 * The years and months units are unaffected.
591 * <p>
592 * This instance is immutable and unaffected by this method call.
593 *
594 * @param days the days to represent, may be negative
595 * @return a {@code Period} based on this period with the requested days, not null
596 */
597 public Period withDays(int days) {
598 if (days == this.days) {
599 return this;
600 }
601 return create(years, months, days);
602 }
603
604 //-----------------------------------------------------------------------
605 /**
606 * Returns a copy of this period with the specified period added.
607 * <p>
608 * This operates separately on the years, months and days.
609 * No normalization is performed.
610 * <p>
611 * For example, "1 year, 6 months and 3 days" plus "2 years, 2 months and 2 days"
612 * returns "3 years, 8 months and 5 days".
613 * <p>
614 * The specified amount is typically an instance of {@code Period}.
615 * Other types are interpreted using {@link Period#from(TemporalAmount)}.
616 * <p>
617 * This instance is immutable and unaffected by this method call.
618 *
619 * @param amountToAdd the amount to add, not null
620 * @return a {@code Period} based on this period with the requested period added, not null
621 * @throws DateTimeException if the specified amount has a non-ISO chronology or
622 * contains an invalid unit
623 * @throws ArithmeticException if numeric overflow occurs
624 */
625 public Period plus(TemporalAmount amountToAdd) {
626 Period isoAmount = Period.from(amountToAdd);
627 return create(
628 Math.addExact(years, isoAmount.years),
629 Math.addExact(months, isoAmount.months),
630 Math.addExact(days, isoAmount.days));
631 }
632
633 /**
634 * Returns a copy of this period with the specified years added.
635 * <p>
636 * This adds the amount to the years unit in a copy of this period.
637 * The months and days units are unaffected.
638 * For example, "1 year, 6 months and 3 days" plus 2 years returns "3 years, 6 months and 3 days".
639 * <p>
640 * This instance is immutable and unaffected by this method call.
641 *
642 * @param yearsToAdd the years to add, positive or negative
643 * @return a {@code Period} based on this period with the specified years added, not null
644 * @throws ArithmeticException if numeric overflow occurs
645 */
646 public Period plusYears(long yearsToAdd) {
647 if (yearsToAdd == 0) {
648 return this;
649 }
650 return create(Math.toIntExact(Math.addExact(years, yearsToAdd)), months, days);
651 }
652
653 /**
654 * Returns a copy of this period with the specified months added.
655 * <p>
656 * This adds the amount to the months unit in a copy of this period.
657 * The years and days units are unaffected.
658 * For example, "1 year, 6 months and 3 days" plus 2 months returns "1 year, 8 months and 3 days".
659 * <p>
660 * This instance is immutable and unaffected by this method call.
661 *
662 * @param monthsToAdd the months to add, positive or negative
663 * @return a {@code Period} based on this period with the specified months added, not null
664 * @throws ArithmeticException if numeric overflow occurs
665 */
666 public Period plusMonths(long monthsToAdd) {
667 if (monthsToAdd == 0) {
668 return this;
669 }
670 return create(years, Math.toIntExact(Math.addExact(months, monthsToAdd)), days);
671 }
672
673 /**
674 * Returns a copy of this period with the specified days added.
675 * <p>
676 * This adds the amount to the days unit in a copy of this period.
677 * The years and months units are unaffected.
678 * For example, "1 year, 6 months and 3 days" plus 2 days returns "1 year, 6 months and 5 days".
679 * <p>
680 * This instance is immutable and unaffected by this method call.
681 *
682 * @param daysToAdd the days to add, positive or negative
683 * @return a {@code Period} based on this period with the specified days added, not null
684 * @throws ArithmeticException if numeric overflow occurs
685 */
686 public Period plusDays(long daysToAdd) {
687 if (daysToAdd == 0) {
688 return this;
689 }
690 return create(years, months, Math.toIntExact(Math.addExact(days, daysToAdd)));
691 }
692
693 //-----------------------------------------------------------------------
694 /**
695 * Returns a copy of this period with the specified period subtracted.
696 * <p>
697 * This operates separately on the years, months and days.
698 * No normalization is performed.
699 * <p>
700 * For example, "1 year, 6 months and 3 days" minus "2 years, 2 months and 2 days"
701 * returns "-1 years, 4 months and 1 day".
702 * <p>
703 * The specified amount is typically an instance of {@code Period}.
704 * Other types are interpreted using {@link Period#from(TemporalAmount)}.
705 * <p>
706 * This instance is immutable and unaffected by this method call.
707 *
708 * @param amountToSubtract the amount to subtract, not null
709 * @return a {@code Period} based on this period with the requested period subtracted, not null
710 * @throws DateTimeException if the specified amount has a non-ISO chronology or
711 * contains an invalid unit
712 * @throws ArithmeticException if numeric overflow occurs
713 */
714 public Period minus(TemporalAmount amountToSubtract) {
715 Period isoAmount = Period.from(amountToSubtract);
716 return create(
717 Math.subtractExact(years, isoAmount.years),
718 Math.subtractExact(months, isoAmount.months),
719 Math.subtractExact(days, isoAmount.days));
720 }
721
722 /**
723 * Returns a copy of this period with the specified years subtracted.
724 * <p>
725 * This subtracts the amount from the years unit in a copy of this period.
726 * The months and days units are unaffected.
727 * For example, "1 year, 6 months and 3 days" minus 2 years returns "-1 years, 6 months and 3 days".
728 * <p>
729 * This instance is immutable and unaffected by this method call.
730 *
731 * @param yearsToSubtract the years to subtract, positive or negative
732 * @return a {@code Period} based on this period with the specified years subtracted, not null
733 * @throws ArithmeticException if numeric overflow occurs
734 */
735 public Period minusYears(long yearsToSubtract) {
736 return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract));
737 }
738
739 /**
740 * Returns a copy of this period with the specified months subtracted.
741 * <p>
742 * This subtracts the amount from the months unit in a copy of this period.
743 * The years and days units are unaffected.
744 * For example, "1 year, 6 months and 3 days" minus 2 months returns "1 year, 4 months and 3 days".
745 * <p>
746 * This instance is immutable and unaffected by this method call.
747 *
748 * @param monthsToSubtract the years to subtract, positive or negative
749 * @return a {@code Period} based on this period with the specified months subtracted, not null
750 * @throws ArithmeticException if numeric overflow occurs
751 */
752 public Period minusMonths(long monthsToSubtract) {
753 return (monthsToSubtract == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-monthsToSubtract));
754 }
755
756 /**
757 * Returns a copy of this period with the specified days subtracted.
758 * <p>
759 * This subtracts the amount from the days unit in a copy of this period.
760 * The years and months units are unaffected.
761 * For example, "1 year, 6 months and 3 days" minus 2 days returns "1 year, 6 months and 1 day".
762 * <p>
763 * This instance is immutable and unaffected by this method call.
764 *
765 * @param daysToSubtract the months to subtract, positive or negative
766 * @return a {@code Period} based on this period with the specified days subtracted, not null
767 * @throws ArithmeticException if numeric overflow occurs
768 */
769 public Period minusDays(long daysToSubtract) {
770 return (daysToSubtract == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-daysToSubtract));
771 }
772
773 //-----------------------------------------------------------------------
774 /**
775 * Returns a new instance with each element in this period multiplied
776 * by the specified scalar.
777 * <p>
778 * This returns a period with each of the years, months and days units
779 * individually multiplied.
780 * For example, a period of "2 years, -3 months and 4 days" multiplied by
781 * 3 will return "6 years, -9 months and 12 days".
782 * No normalization is performed.
783 *
784 * @param scalar the scalar to multiply by, not null
785 * @return a {@code Period} based on this period with the amounts multiplied by the scalar, not null
786 * @throws ArithmeticException if numeric overflow occurs
787 */
788 public Period multipliedBy(int scalar) {
789 if (this == ZERO || scalar == 1) {
790 return this;
791 }
792 return create(
793 Math.multiplyExact(years, scalar),
794 Math.multiplyExact(months, scalar),
795 Math.multiplyExact(days, scalar));
796 }
797
798 /**
799 * Returns a new instance with each amount in this period negated.
800 * <p>
801 * This returns a period with each of the years, months and days units
802 * individually negated.
803 * For example, a period of "2 years, -3 months and 4 days" will be
804 * negated to "-2 years, 3 months and -4 days".
805 * No normalization is performed.
806 *
807 * @return a {@code Period} based on this period with the amounts negated, not null
808 * @throws ArithmeticException if numeric overflow occurs, which only happens if
809 * one of the units has the value {@code Long.MIN_VALUE}
810 */
811 public Period negated() {
812 return multipliedBy(-1);
813 }
814
815 //-----------------------------------------------------------------------
816 /**
817 * Returns a copy of this period with the years and months normalized.
818 * <p>
819 * This normalizes the years and months units, leaving the days unit unchanged.
820 * The months unit is adjusted to have an absolute value less than 11,
821 * with the years unit being adjusted to compensate. For example, a period of
822 * "1 Year and 15 months" will be normalized to "2 years and 3 months".
823 * <p>
824 * The sign of the years and months units will be the same after normalization.
825 * For example, a period of "1 year and -25 months" will be normalized to
826 * "-1 year and -1 month".
827 * <p>
828 * This instance is immutable and unaffected by this method call.
829 *
830 * @return a {@code Period} based on this period with excess months normalized to years, not null
831 * @throws ArithmeticException if numeric overflow occurs
832 */
833 public Period normalized() {
834 long totalMonths = toTotalMonths();
835 long splitYears = totalMonths / 12;
836 int splitMonths = (int) (totalMonths % 12); // no overflow
837 if (splitYears == years && splitMonths == months) {
838 return this;
839 }
840 return create(Math.toIntExact(splitYears), splitMonths, days);
841 }
842
843 /**
844 * Gets the total number of months in this period.
845 * <p>
846 * This returns the total number of months in the period by multiplying the
847 * number of years by 12 and adding the number of months.
848 * <p>
849 * This instance is immutable and unaffected by this method call.
850 *
851 * @return the total number of months in the period, may be negative
852 */
853 public long toTotalMonths() {
854 return years * 12L + months; // no overflow
855 }
856
857 //-------------------------------------------------------------------------
858 /**
859 * Adds this period to the specified temporal object.
860 * <p>
861 * This returns a temporal object of the same observable type as the input
862 * with this period added.
863 * If the temporal has a chronology, it must be the ISO chronology.
864 * <p>
865 * In most cases, it is clearer to reverse the calling pattern by using
866 * {@link Temporal#plus(TemporalAmount)}.
867 * <pre>
868 * // these two lines are equivalent, but the second approach is recommended
869 * dateTime = thisPeriod.addTo(dateTime);
870 * dateTime = dateTime.plus(thisPeriod);
871 * </pre>
872 * <p>
873 * The calculation operates as follows.
874 * First, the chronology of the temporal is checked to ensure it is ISO chronology or null.
875 * Second, if the months are zero, the years are added if non-zero, otherwise
876 * the combination of years and months is added if non-zero.
877 * Finally, any days are added.
878 * <p>
879 * This approach ensures that a partial period can be added to a partial date.
880 * For example, a period of years and/or months can be added to a {@code YearMonth},
881 * but a period including days cannot.
882 * The approach also adds years and months together when necessary, which ensures
883 * correct behaviour at the end of the month.
884 * <p>
885 * This instance is immutable and unaffected by this method call.
886 *
887 * @param temporal the temporal object to adjust, not null
888 * @return an object of the same type with the adjustment made, not null
889 * @throws DateTimeException if unable to add
890 * @throws ArithmeticException if numeric overflow occurs
891 */
892 @Override
893 public Temporal addTo(Temporal temporal) {
894 validateChrono(temporal);
895 if (months == 0) {
896 if (years != 0) {
897 temporal = temporal.plus(years, YEARS);
898 }
899 } else {
900 long totalMonths = toTotalMonths();
901 if (totalMonths != 0) {
902 temporal = temporal.plus(totalMonths, MONTHS);
903 }
904 }
905 if (days != 0) {
906 temporal = temporal.plus(days, DAYS);
907 }
908 return temporal;
909 }
910
911 /**
912 * Subtracts this period from the specified temporal object.
913 * <p>
914 * This returns a temporal object of the same observable type as the input
915 * with this period subtracted.
916 * If the temporal has a chronology, it must be the ISO chronology.
917 * <p>
918 * In most cases, it is clearer to reverse the calling pattern by using
919 * {@link Temporal#minus(TemporalAmount)}.
920 * <pre>
921 * // these two lines are equivalent, but the second approach is recommended
922 * dateTime = thisPeriod.subtractFrom(dateTime);
923 * dateTime = dateTime.minus(thisPeriod);
924 * </pre>
925 * <p>
926 * The calculation operates as follows.
927 * First, the chronology of the temporal is checked to ensure it is ISO chronology or null.
928 * Second, if the months are zero, the years are subtracted if non-zero, otherwise
929 * the combination of years and months is subtracted if non-zero.
930 * Finally, any days are subtracted.
931 * <p>
932 * This approach ensures that a partial period can be subtracted from a partial date.
933 * For example, a period of years and/or months can be subtracted from a {@code YearMonth},
934 * but a period including days cannot.
935 * The approach also subtracts years and months together when necessary, which ensures
936 * correct behaviour at the end of the month.
937 * <p>
938 * This instance is immutable and unaffected by this method call.
939 *
940 * @param temporal the temporal object to adjust, not null
941 * @return an object of the same type with the adjustment made, not null
942 * @throws DateTimeException if unable to subtract
943 * @throws ArithmeticException if numeric overflow occurs
944 */
945 @Override
946 public Temporal subtractFrom(Temporal temporal) {
947 validateChrono(temporal);
948 if (months == 0) {
949 if (years != 0) {
950 temporal = temporal.minus(years, YEARS);
951 }
952 } else {
953 long totalMonths = toTotalMonths();
954 if (totalMonths != 0) {
955 temporal = temporal.minus(totalMonths, MONTHS);
956 }
957 }
958 if (days != 0) {
959 temporal = temporal.minus(days, DAYS);
960 }
961 return temporal;
962 }
963
964 /**
965 * Validates that the temporal has the correct chronology.
966 */
967 private void validateChrono(TemporalAccessor temporal) {
968 Objects.requireNonNull(temporal, "temporal");
969 Chronology temporalChrono = temporal.query(TemporalQueries.chronology());
970 if (temporalChrono != null && IsoChronology.INSTANCE.equals(temporalChrono) == false) {
971 throw new DateTimeException("Chronology mismatch, expected: ISO, actual: " + temporalChrono.getId());
972 }
973 }
974
975 //-----------------------------------------------------------------------
976 /**
977 * Checks if this period is equal to another period.
978 * <p>
979 * The comparison is based on the type {@code Period} and each of the three amounts.
980 * To be equal, the years, months and days units must be individually equal.
981 * Note that this means that a period of "15 Months" is not equal to a period
982 * of "1 Year and 3 Months".
983 *
984 * @param obj the object to check, null returns false
985 * @return true if this is equal to the other period
986 */
987 @Override
988 public boolean equals(Object obj) {
989 if (this == obj) {
990 return true;
991 }
992 if (obj instanceof Period) {
993 Period other = (Period) obj;
994 return years == other.years &&
995 months == other.months &&
996 days == other.days;
997 }
998 return false;
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="../../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 private Object writeReplace() {
1055 return new Ser(Ser.PERIOD_TYPE, this);
1056 }
1057
1058 /**
1059 * Defend against malicious streams.
1060 *
1061 * @param s the stream to read
1062 * @throws java.io.InvalidObjectException always
1063 */
1064 private void readObject(ObjectInputStream s) throws InvalidObjectException {
1065 throw new InvalidObjectException("Deserialization via serialization delegate");
1066 }
1067
1068 void writeExternal(DataOutput out) throws IOException {
1069 out.writeInt(years);
1070 out.writeInt(months);
1071 out.writeInt(days);
1072 }
1073
1074 static Period readExternal(DataInput in) throws IOException {
1075 int years = in.readInt();
1076 int months = in.readInt();
1077 int days = in.readInt();
1078 return Period.of(years, months, days);
1079 }
1080
1081 }