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 = (charMatch(text, matcher.start(1), matcher.end(1), '-') ? -1 : 1);
333 int yearStart = matcher.start(2), yearEnd = matcher.end(2);
334 int monthStart = matcher.start(3), monthEnd = matcher.end(3);
335 int weekStart = matcher.start(4), weekEnd = matcher.end(4);
336 int dayStart = matcher.start(5), dayEnd = matcher.end(5);
337 if (yearStart >= 0 || monthStart >= 0 || weekStart >= 0 || dayStart >= 0) {
338 try {
339 int years = parseNumber(text, yearStart, yearEnd, negate);
340 int months = parseNumber(text, monthStart, monthEnd, negate);
341 int weeks = parseNumber(text, weekStart, weekEnd, negate);
342 int days = parseNumber(text, dayStart, dayEnd, 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 boolean charMatch(CharSequence text, int start, int end, char c) {
354 return (start >= 0 && end == start + 1 && text.charAt(start) == c);
355 }
356
357 private static int parseNumber(CharSequence text, int start, int end, int negate) {
358 if (start < 0 || end < 0) {
359 return 0;
360 }
361 int val = Integer.parseInt(text, start, end, 10);
362 try {
363 return Math.multiplyExact(val, negate);
364 } catch (ArithmeticException ex) {
365 throw new DateTimeParseException("Text cannot be parsed to a Period", text, 0, ex);
366 }
367 }
368
369 //-----------------------------------------------------------------------
370 /**
371 * Obtains a {@code Period} consisting of the number of years, months,
372 * and days between two dates.
373 * <p>
374 * The start date is included, but the end date is not.
375 * The period is calculated by removing complete months, then calculating
376 * the remaining number of days, adjusting to ensure that both have the same sign.
377 * The number of months is then split into years and months based on a 12 month year.
378 * A month is considered if the end day-of-month is greater than or equal to the start day-of-month.
379 * For example, from {@code 2010-01-15} to {@code 2011-03-18} is one year, two months and three days.
380 * <p>
381 * The result of this method can be a negative period if the end is before the start.
382 * The negative sign will be the same in each of year, month and day.
383 *
384 * @param startDateInclusive the start date, inclusive, not null
385 * @param endDateExclusive the end date, exclusive, not null
386 * @return the period between this date and the end date, not null
387 * @see ChronoLocalDate#until(ChronoLocalDate)
388 */
389 public static Period between(LocalDate startDateInclusive, LocalDate endDateExclusive) {
390 return startDateInclusive.until(endDateExclusive);
391 }
392
393 //-----------------------------------------------------------------------
394 /**
395 * Creates an instance.
396 *
397 * @param years the amount
398 * @param months the amount
399 * @param days the amount
400 */
401 private static Period create(int years, int months, int days) {
402 if ((years | months | days) == 0) {
403 return ZERO;
404 }
405 return new Period(years, months, days);
406 }
407
408 /**
409 * Constructor.
410 *
411 * @param years the amount
412 * @param months the amount
413 * @param days the amount
414 */
415 private Period(int years, int months, int days) {
416 this.years = years;
417 this.months = months;
418 this.days = days;
419 }
420
421 //-----------------------------------------------------------------------
422 /**
423 * Gets the value of the requested unit.
424 * <p>
425 * This returns a value for each of the three supported units,
426 * {@link ChronoUnit#YEARS YEARS}, {@link ChronoUnit#MONTHS MONTHS} and
427 * {@link ChronoUnit#DAYS DAYS}.
428 * All other units throw an exception.
429 *
430 * @param unit the {@code TemporalUnit} for which to return the value
431 * @return the long value of the unit
432 * @throws DateTimeException if the unit is not supported
433 * @throws UnsupportedTemporalTypeException if the unit is not supported
434 */
435 @Override
436 public long get(TemporalUnit unit) {
437 if (unit == ChronoUnit.YEARS) {
438 return getYears();
439 } else if (unit == ChronoUnit.MONTHS) {
440 return getMonths();
441 } else if (unit == ChronoUnit.DAYS) {
442 return getDays();
443 } else {
444 throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
445 }
446 }
447
448 /**
449 * Gets the set of units supported by this period.
450 * <p>
451 * The supported units are {@link ChronoUnit#YEARS YEARS},
452 * {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS}.
453 * They are returned in the order years, months, days.
454 * <p>
455 * This set can be used in conjunction with {@link #get(TemporalUnit)}
456 * to access the entire state of the period.
457 *
458 * @return a list containing the years, months and days units, not null
459 */
460 @Override
461 public List<TemporalUnit> getUnits() {
462 return SUPPORTED_UNITS;
463 }
464
465 /**
466 * Gets the chronology of this period, which is the ISO calendar system.
467 * <p>
468 * The {@code Chronology} represents the calendar system in use.
469 * The ISO-8601 calendar system is the modern civil calendar system used today
470 * in most of the world. It is equivalent to the proleptic Gregorian calendar
471 * system, in which today's rules for leap years are applied for all time.
472 *
473 * @return the ISO chronology, not null
474 */
475 @Override
476 public IsoChronology getChronology() {
477 return IsoChronology.INSTANCE;
478 }
479
480 //-----------------------------------------------------------------------
481 /**
482 * Checks if all three units of this period are zero.
483 * <p>
484 * A zero period has the value zero for the years, months and days units.
485 *
486 * @return true if this period is zero-length
487 */
488 public boolean isZero() {
489 return (this == ZERO);
490 }
491
492 /**
493 * Checks if any of the three units of this period are negative.
494 * <p>
495 * This checks whether the years, months or days units are less than zero.
496 *
497 * @return true if any unit of this period is negative
498 */
499 public boolean isNegative() {
500 return years < 0 || months < 0 || days < 0;
501 }
502
503 //-----------------------------------------------------------------------
504 /**
505 * Gets the amount of years of this period.
506 * <p>
507 * This returns the years unit.
508 * <p>
509 * The months unit is not automatically normalized with the years unit.
510 * This means that a period of "15 months" is different to a period
511 * of "1 year and 3 months".
512 *
513 * @return the amount of years of this period, may be negative
514 */
515 public int getYears() {
516 return years;
517 }
518
519 /**
520 * Gets the amount of months of this period.
521 * <p>
522 * This returns the months unit.
523 * <p>
524 * The months unit is not automatically normalized with the years unit.
525 * This means that a period of "15 months" is different to a period
526 * of "1 year and 3 months".
527 *
528 * @return the amount of months of this period, may be negative
529 */
530 public int getMonths() {
531 return months;
532 }
533
534 /**
535 * Gets the amount of days of this period.
536 * <p>
537 * This returns the days unit.
538 *
539 * @return the amount of days of this period, may be negative
540 */
541 public int getDays() {
542 return days;
543 }
544
545 //-----------------------------------------------------------------------
546 /**
547 * Returns a copy of this period with the specified amount of years.
548 * <p>
549 * This sets the amount of the years unit in a copy of this period.
550 * The months and days units are unaffected.
551 * <p>
552 * The months unit is not automatically normalized with the years unit.
553 * This means that a period of "15 months" is different to a period
554 * of "1 year and 3 months".
555 * <p>
556 * This instance is immutable and unaffected by this method call.
557 *
558 * @param years the years to represent, may be negative
559 * @return a {@code Period} based on this period with the requested years, not null
560 */
561 public Period withYears(int years) {
562 if (years == this.years) {
563 return this;
564 }
565 return create(years, months, days);
566 }
567
568 /**
569 * Returns a copy of this period with the specified amount of months.
570 * <p>
571 * This sets the amount of the months unit in a copy of this period.
572 * The years and days units are unaffected.
573 * <p>
574 * The months unit is not automatically normalized with the years unit.
575 * This means that a period of "15 months" is different to a period
576 * of "1 year and 3 months".
577 * <p>
578 * This instance is immutable and unaffected by this method call.
579 *
580 * @param months the months to represent, may be negative
581 * @return a {@code Period} based on this period with the requested months, not null
582 */
583 public Period withMonths(int months) {
584 if (months == this.months) {
585 return this;
586 }
587 return create(years, months, days);
588 }
589
590 /**
591 * Returns a copy of this period with the specified amount of days.
592 * <p>
593 * This sets the amount of the days unit in a copy of this period.
594 * The years and months units are unaffected.
595 * <p>
596 * This instance is immutable and unaffected by this method call.
597 *
598 * @param days the days to represent, may be negative
599 * @return a {@code Period} based on this period with the requested days, not null
600 */
601 public Period withDays(int days) {
602 if (days == this.days) {
603 return this;
604 }
605 return create(years, months, days);
606 }
607
608 //-----------------------------------------------------------------------
609 /**
610 * Returns a copy of this period with the specified period added.
611 * <p>
612 * This operates separately on the years, months and days.
613 * No normalization is performed.
614 * <p>
615 * For example, "1 year, 6 months and 3 days" plus "2 years, 2 months and 2 days"
616 * returns "3 years, 8 months and 5 days".
617 * <p>
618 * The specified amount is typically an instance of {@code Period}.
619 * Other types are interpreted using {@link Period#from(TemporalAmount)}.
620 * <p>
621 * This instance is immutable and unaffected by this method call.
622 *
623 * @param amountToAdd the amount to add, not null
624 * @return a {@code Period} based on this period with the requested period added, not null
625 * @throws DateTimeException if the specified amount has a non-ISO chronology or
626 * contains an invalid unit
627 * @throws ArithmeticException if numeric overflow occurs
628 */
629 public Period plus(TemporalAmount amountToAdd) {
630 Period isoAmount = Period.from(amountToAdd);
631 return create(
632 Math.addExact(years, isoAmount.years),
633 Math.addExact(months, isoAmount.months),
634 Math.addExact(days, isoAmount.days));
635 }
636
637 /**
638 * Returns a copy of this period with the specified years added.
639 * <p>
640 * This adds the amount to the years unit in a copy of this period.
641 * The months and days units are unaffected.
642 * For example, "1 year, 6 months and 3 days" plus 2 years returns "3 years, 6 months and 3 days".
643 * <p>
644 * This instance is immutable and unaffected by this method call.
645 *
646 * @param yearsToAdd the years to add, positive or negative
647 * @return a {@code Period} based on this period with the specified years added, not null
648 * @throws ArithmeticException if numeric overflow occurs
649 */
650 public Period plusYears(long yearsToAdd) {
651 if (yearsToAdd == 0) {
652 return this;
653 }
654 return create(Math.toIntExact(Math.addExact(years, yearsToAdd)), months, days);
655 }
656
657 /**
658 * Returns a copy of this period with the specified months added.
659 * <p>
660 * This adds the amount to the months unit in a copy of this period.
661 * The years and days units are unaffected.
662 * For example, "1 year, 6 months and 3 days" plus 2 months returns "1 year, 8 months and 3 days".
663 * <p>
664 * This instance is immutable and unaffected by this method call.
665 *
666 * @param monthsToAdd the months to add, positive or negative
667 * @return a {@code Period} based on this period with the specified months added, not null
668 * @throws ArithmeticException if numeric overflow occurs
669 */
670 public Period plusMonths(long monthsToAdd) {
671 if (monthsToAdd == 0) {
672 return this;
673 }
674 return create(years, Math.toIntExact(Math.addExact(months, monthsToAdd)), days);
675 }
676
677 /**
678 * Returns a copy of this period with the specified days added.
679 * <p>
680 * This adds the amount to the days unit in a copy of this period.
681 * The years and months units are unaffected.
682 * For example, "1 year, 6 months and 3 days" plus 2 days returns "1 year, 6 months and 5 days".
683 * <p>
684 * This instance is immutable and unaffected by this method call.
685 *
686 * @param daysToAdd the days to add, positive or negative
687 * @return a {@code Period} based on this period with the specified days added, not null
688 * @throws ArithmeticException if numeric overflow occurs
689 */
690 public Period plusDays(long daysToAdd) {
691 if (daysToAdd == 0) {
692 return this;
693 }
694 return create(years, months, Math.toIntExact(Math.addExact(days, daysToAdd)));
695 }
696
697 //-----------------------------------------------------------------------
698 /**
699 * Returns a copy of this period with the specified period subtracted.
700 * <p>
701 * This operates separately on the years, months and days.
702 * No normalization is performed.
703 * <p>
704 * For example, "1 year, 6 months and 3 days" minus "2 years, 2 months and 2 days"
705 * returns "-1 years, 4 months and 1 day".
706 * <p>
707 * The specified amount is typically an instance of {@code Period}.
708 * Other types are interpreted using {@link Period#from(TemporalAmount)}.
709 * <p>
710 * This instance is immutable and unaffected by this method call.
711 *
712 * @param amountToSubtract the amount to subtract, not null
713 * @return a {@code Period} based on this period with the requested period subtracted, not null
714 * @throws DateTimeException if the specified amount has a non-ISO chronology or
715 * contains an invalid unit
716 * @throws ArithmeticException if numeric overflow occurs
717 */
718 public Period minus(TemporalAmount amountToSubtract) {
719 Period isoAmount = Period.from(amountToSubtract);
720 return create(
721 Math.subtractExact(years, isoAmount.years),
722 Math.subtractExact(months, isoAmount.months),
723 Math.subtractExact(days, isoAmount.days));
724 }
725
726 /**
727 * Returns a copy of this period with the specified years subtracted.
728 * <p>
729 * This subtracts the amount from the years unit in a copy of this period.
730 * The months and days units are unaffected.
731 * For example, "1 year, 6 months and 3 days" minus 2 years returns "-1 years, 6 months and 3 days".
732 * <p>
733 * This instance is immutable and unaffected by this method call.
734 *
735 * @param yearsToSubtract the years to subtract, positive or negative
736 * @return a {@code Period} based on this period with the specified years subtracted, not null
737 * @throws ArithmeticException if numeric overflow occurs
738 */
739 public Period minusYears(long yearsToSubtract) {
740 return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract));
741 }
742
743 /**
744 * Returns a copy of this period with the specified months subtracted.
745 * <p>
746 * This subtracts the amount from the months unit in a copy of this period.
747 * The years and days units are unaffected.
748 * For example, "1 year, 6 months and 3 days" minus 2 months returns "1 year, 4 months and 3 days".
749 * <p>
750 * This instance is immutable and unaffected by this method call.
751 *
752 * @param monthsToSubtract the years to subtract, positive or negative
753 * @return a {@code Period} based on this period with the specified months subtracted, not null
754 * @throws ArithmeticException if numeric overflow occurs
755 */
756 public Period minusMonths(long monthsToSubtract) {
757 return (monthsToSubtract == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-monthsToSubtract));
758 }
759
760 /**
761 * Returns a copy of this period with the specified days subtracted.
762 * <p>
763 * This subtracts the amount from the days unit in a copy of this period.
764 * The years and months units are unaffected.
765 * For example, "1 year, 6 months and 3 days" minus 2 days returns "1 year, 6 months and 1 day".
766 * <p>
767 * This instance is immutable and unaffected by this method call.
768 *
769 * @param daysToSubtract the months to subtract, positive or negative
770 * @return a {@code Period} based on this period with the specified days subtracted, not null
771 * @throws ArithmeticException if numeric overflow occurs
772 */
773 public Period minusDays(long daysToSubtract) {
774 return (daysToSubtract == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-daysToSubtract));
775 }
776
777 //-----------------------------------------------------------------------
778 /**
779 * Returns a new instance with each element in this period multiplied
780 * by the specified scalar.
781 * <p>
782 * This returns a period with each of the years, months and days units
783 * individually multiplied.
784 * For example, a period of "2 years, -3 months and 4 days" multiplied by
785 * 3 will return "6 years, -9 months and 12 days".
786 * No normalization is performed.
787 *
788 * @param scalar the scalar to multiply by, not null
789 * @return a {@code Period} based on this period with the amounts multiplied by the scalar, not null
790 * @throws ArithmeticException if numeric overflow occurs
791 */
792 public Period multipliedBy(int scalar) {
793 if (this == ZERO || scalar == 1) {
794 return this;
795 }
796 return create(
797 Math.multiplyExact(years, scalar),
798 Math.multiplyExact(months, scalar),
799 Math.multiplyExact(days, scalar));
800 }
801
802 /**
803 * Returns a new instance with each amount in this period negated.
804 * <p>
805 * This returns a period with each of the years, months and days units
806 * individually negated.
807 * For example, a period of "2 years, -3 months and 4 days" will be
808 * negated to "-2 years, 3 months and -4 days".
809 * No normalization is performed.
810 *
811 * @return a {@code Period} based on this period with the amounts negated, not null
812 * @throws ArithmeticException if numeric overflow occurs, which only happens if
813 * one of the units has the value {@code Long.MIN_VALUE}
814 */
815 public Period negated() {
816 return multipliedBy(-1);
817 }
818
819 //-----------------------------------------------------------------------
820 /**
821 * Returns a copy of this period with the years and months normalized.
822 * <p>
823 * This normalizes the years and months units, leaving the days unit unchanged.
824 * The months unit is adjusted to have an absolute value less than 11,
825 * with the years unit being adjusted to compensate. For example, a period of
826 * "1 Year and 15 months" will be normalized to "2 years and 3 months".
827 * <p>
828 * The sign of the years and months units will be the same after normalization.
829 * For example, a period of "1 year and -25 months" will be normalized to
830 * "-1 year and -1 month".
831 * <p>
832 * This instance is immutable and unaffected by this method call.
833 *
834 * @return a {@code Period} based on this period with excess months normalized to years, not null
835 * @throws ArithmeticException if numeric overflow occurs
836 */
837 public Period normalized() {
838 long totalMonths = toTotalMonths();
839 long splitYears = totalMonths / 12;
840 int splitMonths = (int) (totalMonths % 12); // no overflow
841 if (splitYears == years && splitMonths == months) {
842 return this;
843 }
844 return create(Math.toIntExact(splitYears), splitMonths, days);
845 }
846
847 /**
848 * Gets the total number of months in this period.
849 * <p>
850 * This returns the total number of months in the period by multiplying the
851 * number of years by 12 and adding the number of months.
852 * <p>
853 * This instance is immutable and unaffected by this method call.
854 *
855 * @return the total number of months in the period, may be negative
856 */
857 public long toTotalMonths() {
858 return years * 12L + months; // no overflow
859 }
860
861 //-------------------------------------------------------------------------
862 /**
863 * Adds this period to the specified temporal object.
864 * <p>
865 * This returns a temporal object of the same observable type as the input
866 * with this period added.
867 * If the temporal has a chronology, it must be the ISO chronology.
868 * <p>
869 * In most cases, it is clearer to reverse the calling pattern by using
870 * {@link Temporal#plus(TemporalAmount)}.
871 * <pre>
872 * // these two lines are equivalent, but the second approach is recommended
873 * dateTime = thisPeriod.addTo(dateTime);
874 * dateTime = dateTime.plus(thisPeriod);
875 * </pre>
876 * <p>
877 * The calculation operates as follows.
878 * First, the chronology of the temporal is checked to ensure it is ISO chronology or null.
879 * Second, if the months are zero, the years are added if non-zero, otherwise
880 * the combination of years and months is added if non-zero.
881 * Finally, any days are added.
882 * <p>
883 * This approach ensures that a partial period can be added to a partial date.
884 * For example, a period of years and/or months can be added to a {@code YearMonth},
885 * but a period including days cannot.
886 * The approach also adds years and months together when necessary, which ensures
887 * correct behaviour at the end of the month.
888 * <p>
889 * This instance is immutable and unaffected by this method call.
890 *
891 * @param temporal the temporal object to adjust, not null
892 * @return an object of the same type with the adjustment made, not null
893 * @throws DateTimeException if unable to add
894 * @throws ArithmeticException if numeric overflow occurs
895 */
896 @Override
897 public Temporal addTo(Temporal temporal) {
898 validateChrono(temporal);
899 if (months == 0) {
900 if (years != 0) {
901 temporal = temporal.plus(years, YEARS);
902 }
903 } else {
904 long totalMonths = toTotalMonths();
905 if (totalMonths != 0) {
906 temporal = temporal.plus(totalMonths, MONTHS);
907 }
908 }
909 if (days != 0) {
910 temporal = temporal.plus(days, DAYS);
911 }
912 return temporal;
913 }
914
915 /**
916 * Subtracts this period from the specified temporal object.
917 * <p>
918 * This returns a temporal object of the same observable type as the input
919 * with this period subtracted.
920 * If the temporal has a chronology, it must be the ISO chronology.
921 * <p>
922 * In most cases, it is clearer to reverse the calling pattern by using
923 * {@link Temporal#minus(TemporalAmount)}.
924 * <pre>
925 * // these two lines are equivalent, but the second approach is recommended
926 * dateTime = thisPeriod.subtractFrom(dateTime);
927 * dateTime = dateTime.minus(thisPeriod);
928 * </pre>
929 * <p>
930 * The calculation operates as follows.
931 * First, the chronology of the temporal is checked to ensure it is ISO chronology or null.
932 * Second, if the months are zero, the years are subtracted if non-zero, otherwise
933 * the combination of years and months is subtracted if non-zero.
934 * Finally, any days are subtracted.
935 * <p>
936 * This approach ensures that a partial period can be subtracted from a partial date.
937 * For example, a period of years and/or months can be subtracted from a {@code YearMonth},
938 * but a period including days cannot.
939 * The approach also subtracts years and months together when necessary, which ensures
940 * correct behaviour at the end of the month.
941 * <p>
942 * This instance is immutable and unaffected by this method call.
943 *
944 * @param temporal the temporal object to adjust, not null
945 * @return an object of the same type with the adjustment made, not null
946 * @throws DateTimeException if unable to subtract
947 * @throws ArithmeticException if numeric overflow occurs
948 */
949 @Override
950 public Temporal subtractFrom(Temporal temporal) {
951 validateChrono(temporal);
952 if (months == 0) {
953 if (years != 0) {
954 temporal = temporal.minus(years, YEARS);
955 }
956 } else {
957 long totalMonths = toTotalMonths();
958 if (totalMonths != 0) {
959 temporal = temporal.minus(totalMonths, MONTHS);
960 }
961 }
962 if (days != 0) {
963 temporal = temporal.minus(days, DAYS);
964 }
965 return temporal;
966 }
967
968 /**
969 * Validates that the temporal has the correct chronology.
970 */
971 private void validateChrono(TemporalAccessor temporal) {
972 Objects.requireNonNull(temporal, "temporal");
973 Chronology temporalChrono = temporal.query(TemporalQueries.chronology());
974 if (temporalChrono != null && IsoChronology.INSTANCE.equals(temporalChrono) == false) {
975 throw new DateTimeException("Chronology mismatch, expected: ISO, actual: " + temporalChrono.getId());
976 }
977 }
978
979 //-----------------------------------------------------------------------
980 /**
981 * Checks if this period is equal to another period.
982 * <p>
983 * The comparison is based on the type {@code Period} and each of the three amounts.
984 * To be equal, the years, months and days units must be individually equal.
985 * Note that this means that a period of "15 Months" is not equal to a period
986 * of "1 Year and 3 Months".
987 *
988 * @param obj the object to check, null returns false
989 * @return true if this is equal to the other period
990 */
991 @Override
992 public boolean equals(Object obj) {
993 if (this == obj) {
994 return true;
995 }
996 if (obj instanceof Period) {
997 Period other = (Period) obj;
998 return years == other.years &&
999 months == other.months &&
1000 days == other.days;
1001 }
1002 return false;
1003 }
1004
1005 /**
1006 * A hash code for this period.
1007 *
1008 * @return a suitable hash code
1009 */
1010 @Override
1011 public int hashCode() {
1012 return years + Integer.rotateLeft(months, 8) + Integer.rotateLeft(days, 16);
1013 }
1014
1015 //-----------------------------------------------------------------------
1016 /**
1017 * Outputs this period as a {@code String}, such as {@code P6Y3M1D}.
1018 * <p>
1019 * The output will be in the ISO-8601 period format.
1020 * A zero period will be represented as zero days, 'P0D'.
1021 *
1022 * @return a string representation of this period, not null
1023 */
1024 @Override
1025 public String toString() {
1026 if (this == ZERO) {
1027 return "P0D";
1028 } else {
1029 StringBuilder buf = new StringBuilder();
1030 buf.append('P');
1031 if (years != 0) {
1032 buf.append(years).append('Y');
1033 }
1034 if (months != 0) {
1035 buf.append(months).append('M');
1036 }
1037 if (days != 0) {
1038 buf.append(days).append('D');
1039 }
1040 return buf.toString();
1041 }
1042 }
1043
1044 //-----------------------------------------------------------------------
1045 /**
1046 * Writes the object using a
1047 * <a href="../../serialized-form.html#java.time.Ser">dedicated serialized form</a>.
1048 * @serialData
1049 * <pre>
1050 * out.writeByte(14); // identifies a Period
1051 * out.writeInt(years);
1052 * out.writeInt(months);
1053 * out.writeInt(days);
1054 * </pre>
1055 *
1056 * @return the instance of {@code Ser}, not null
1057 */
1058 private Object writeReplace() {
1059 return new Ser(Ser.PERIOD_TYPE, this);
1060 }
1061
1062 /**
1063 * Defend against malicious streams.
1064 *
1065 * @param s the stream to read
1066 * @throws java.io.InvalidObjectException always
1067 */
1068 private void readObject(ObjectInputStream s) throws InvalidObjectException {
1069 throw new InvalidObjectException("Deserialization via serialization delegate");
1070 }
1071
1072 void writeExternal(DataOutput out) throws IOException {
1073 out.writeInt(years);
1074 out.writeInt(months);
1075 out.writeInt(days);
1076 }
1077
1078 static Period readExternal(DataInput in) throws IOException {
1079 int years = in.readInt();
1080 int months = in.readInt();
1081 int days = in.readInt();
1082 return Period.of(years, months, days);
1083 }
1084
1085 }