1 /*
2 * Copyright (c) 2012, 2016, 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 *
121 * <p>
122 * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
123 * class; use of identity-sensitive operations (including reference equality
124 * ({@code ==}), identity hash code, or synchronization) on instances of
125 * {@code Period} may have unpredictable results and should be avoided.
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 public final class Period
134 implements ChronoPeriod, Serializable {
135
136 /**
137 * A constant for a period of zero.
138 */
139 public static final Period ZERO = new Period(0, 0, 0);
140 /**
141 * Serialization version.
142 */
143 private static final long serialVersionUID = -3587258372562876L;
144 /**
145 * The pattern for parsing.
146 */
147 private static final Pattern PATTERN =
148 Pattern.compile("([-+]?)P(?:([-+]?[0-9]+)Y)?(?:([-+]?[0-9]+)M)?(?:([-+]?[0-9]+)W)?(?:([-+]?[0-9]+)D)?", Pattern.CASE_INSENSITIVE);
149
150 /**
151 * The set of supported units.
152 */
153 private static final List<TemporalUnit> SUPPORTED_UNITS = List.of(YEARS, MONTHS, DAYS);
154
155 /**
156 * The number of years.
157 */
158 private final int years;
159 /**
160 * The number of months.
161 */
162 private final int months;
163 /**
164 * The number of days.
165 */
166 private final int days;
167
168 //-----------------------------------------------------------------------
169 /**
170 * Obtains a {@code Period} representing a number of years.
171 * <p>
172 * The resulting period will have the specified years.
173 * The months and days units will be zero.
174 *
175 * @param years the number of years, positive or negative
176 * @return the period of years, not null
177 */
178 public static Period ofYears(int years) {
179 return create(years, 0, 0);
180 }
181
182 /**
183 * Obtains a {@code Period} representing a number of months.
184 * <p>
185 * The resulting period will have the specified months.
186 * The years and days units will be zero.
187 *
188 * @param months the number of months, positive or negative
189 * @return the period of months, not null
190 */
191 public static Period ofMonths(int months) {
192 return create(0, months, 0);
193 }
194
195 /**
196 * Obtains a {@code Period} representing a number of weeks.
197 * <p>
198 * The resulting period will be day-based, with the amount of days
199 * equal to the number of weeks multiplied by 7.
200 * The years and months units will be zero.
201 *
202 * @param weeks the number of weeks, positive or negative
203 * @return the period, with the input weeks converted to days, not null
204 */
205 public static Period ofWeeks(int weeks) {
206 return create(0, 0, Math.multiplyExact(weeks, 7));
207 }
208
209 /**
210 * Obtains a {@code Period} representing a number of days.
211 * <p>
212 * The resulting period will have the specified days.
213 * The years and months units will be zero.
214 *
215 * @param days the number of days, positive or negative
216 * @return the period of days, not null
217 */
218 public static Period ofDays(int days) {
219 return create(0, 0, days);
220 }
221
222 //-----------------------------------------------------------------------
223 /**
224 * Obtains a {@code Period} representing a number of years, months and days.
225 * <p>
226 * This creates an instance based on years, months and days.
227 *
228 * @param years the amount of years, may be negative
229 * @param months the amount of months, may be negative
230 * @param days the amount of days, may be negative
231 * @return the period of years, months and days, not null
232 */
233 public static Period of(int years, int months, int days) {
234 return create(years, months, days);
235 }
236
237 //-----------------------------------------------------------------------
238 /**
239 * Obtains an instance of {@code Period} from a temporal amount.
240 * <p>
241 * This obtains a period based on the specified amount.
242 * A {@code TemporalAmount} represents an amount of time, which may be
243 * date-based or time-based, which this factory extracts to a {@code Period}.
244 * <p>
245 * The conversion loops around the set of units from the amount and uses
246 * the {@link ChronoUnit#YEARS YEARS}, {@link ChronoUnit#MONTHS MONTHS}
247 * and {@link ChronoUnit#DAYS DAYS} units to create a period.
248 * If any other units are found then an exception is thrown.
249 * <p>
250 * If the amount is a {@code ChronoPeriod} then it must use the ISO chronology.
251 *
252 * @param amount the temporal amount to convert, not null
253 * @return the equivalent period, not null
254 * @throws DateTimeException if unable to convert to a {@code Period}
255 * @throws ArithmeticException if the amount of years, months or days exceeds an int
256 */
257 public static Period from(TemporalAmount amount) {
258 if (amount instanceof Period) {
259 return (Period) amount;
260 }
261 if (amount instanceof ChronoPeriod) {
262 if (IsoChronology.INSTANCE.equals(((ChronoPeriod) amount).getChronology()) == false) {
263 throw new DateTimeException("Period requires ISO chronology: " + amount);
264 }
265 }
266 Objects.requireNonNull(amount, "amount");
267 int years = 0;
268 int months = 0;
269 int days = 0;
270 for (TemporalUnit unit : amount.getUnits()) {
271 long unitAmount = amount.get(unit);
272 if (unit == ChronoUnit.YEARS) {
273 years = Math.toIntExact(unitAmount);
274 } else if (unit == ChronoUnit.MONTHS) {
275 months = Math.toIntExact(unitAmount);
276 } else if (unit == ChronoUnit.DAYS) {
277 days = Math.toIntExact(unitAmount);
278 } else {
279 throw new DateTimeException("Unit must be Years, Months or Days, but was " + unit);
280 }
281 }
282 return create(years, months, days);
283 }
284
285 //-----------------------------------------------------------------------
286 /**
287 * Obtains a {@code Period} from a text string such as {@code PnYnMnD}.
288 * <p>
289 * This will parse the string produced by {@code toString()} which is
290 * based on the ISO-8601 period formats {@code PnYnMnD} and {@code PnW}.
291 * <p>
292 * The string starts with an optional sign, denoted by the ASCII negative
293 * or positive symbol. If negative, the whole period is negated.
294 * The ASCII letter "P" is next in upper or lower case.
295 * There are then four sections, each consisting of a number and a suffix.
296 * At least one of the four sections must be present.
297 * The sections have suffixes in ASCII of "Y", "M", "W" and "D" for
298 * years, months, weeks and days, accepted in upper or lower case.
299 * The suffixes must occur in order.
300 * The number part of each section must consist of ASCII digits.
301 * The number may be prefixed by the ASCII negative or positive symbol.
302 * The number must parse to an {@code int}.
303 * <p>
304 * The leading plus/minus sign, and negative values for other units are
305 * not part of the ISO-8601 standard. In addition, ISO-8601 does not
306 * permit mixing between the {@code PnYnMnD} and {@code PnW} formats.
307 * Any week-based input is multiplied by 7 and treated as a number of days.
308 * <p>
309 * For example, the following are valid inputs:
310 * <pre>
311 * "P2Y" -- Period.ofYears(2)
312 * "P3M" -- Period.ofMonths(3)
313 * "P4W" -- Period.ofWeeks(4)
314 * "P5D" -- Period.ofDays(5)
315 * "P1Y2M3D" -- Period.of(1, 2, 3)
316 * "P1Y2M3W4D" -- Period.of(1, 2, 25)
317 * "P-1Y2M" -- Period.of(-1, 2, 0)
318 * "-P1Y2M" -- Period.of(-1, -2, 0)
319 * </pre>
320 *
321 * @param text the text to parse, not null
322 * @return the parsed period, not null
323 * @throws DateTimeParseException if the text cannot be parsed to a period
324 */
325 public static Period parse(CharSequence text) {
326 Objects.requireNonNull(text, "text");
327 Matcher matcher = PATTERN.matcher(text);
328 if (matcher.matches()) {
329 int negate = (charMatch(text, matcher.start(1), matcher.end(1), '-') ? -1 : 1);
330 int yearStart = matcher.start(2), yearEnd = matcher.end(2);
331 int monthStart = matcher.start(3), monthEnd = matcher.end(3);
332 int weekStart = matcher.start(4), weekEnd = matcher.end(4);
333 int dayStart = matcher.start(5), dayEnd = matcher.end(5);
334 if (yearStart >= 0 || monthStart >= 0 || weekStart >= 0 || dayStart >= 0) {
335 try {
336 int years = parseNumber(text, yearStart, yearEnd, negate);
337 int months = parseNumber(text, monthStart, monthEnd, negate);
338 int weeks = parseNumber(text, weekStart, weekEnd, negate);
339 int days = parseNumber(text, dayStart, dayEnd, negate);
340 days = Math.addExact(days, Math.multiplyExact(weeks, 7));
341 return create(years, months, days);
342 } catch (NumberFormatException ex) {
343 throw new DateTimeParseException("Text cannot be parsed to a Period", text, 0, ex);
344 }
345 }
346 }
347 throw new DateTimeParseException("Text cannot be parsed to a Period", text, 0);
348 }
349
350 private static boolean charMatch(CharSequence text, int start, int end, char c) {
351 return (start >= 0 && end == start + 1 && text.charAt(start) == c);
352 }
353
354 private static int parseNumber(CharSequence text, int start, int end, int negate) {
355 if (start < 0 || end < 0) {
356 return 0;
357 }
358 int val = Integer.parseInt(text, start, end, 10);
359 try {
360 return Math.multiplyExact(val, negate);
361 } catch (ArithmeticException ex) {
362 throw new DateTimeParseException("Text cannot be parsed to a Period", text, 0, ex);
363 }
364 }
365
366 //-----------------------------------------------------------------------
367 /**
368 * Obtains a {@code Period} consisting of the number of years, months,
369 * and days between two dates.
370 * <p>
371 * The start date is included, but the end date is not.
372 * The period is calculated by removing complete months, then calculating
373 * the remaining number of days, adjusting to ensure that both have the same sign.
374 * The number of months is then split into years and months based on a 12 month year.
375 * A month is considered if the end day-of-month is greater than or equal to the start day-of-month.
376 * For example, from {@code 2010-01-15} to {@code 2011-03-18} is one year, two months and three days.
377 * <p>
378 * The result of this method can be a negative period if the end is before the start.
379 * The negative sign will be the same in each of year, month and day.
380 *
381 * @param startDateInclusive the start date, inclusive, not null
382 * @param endDateExclusive the end date, exclusive, not null
383 * @return the period between this date and the end date, not null
384 * @see ChronoLocalDate#until(ChronoLocalDate)
385 */
386 public static Period between(LocalDate startDateInclusive, LocalDate endDateExclusive) {
387 return startDateInclusive.until(endDateExclusive);
388 }
389
390 //-----------------------------------------------------------------------
391 /**
392 * Creates an instance.
393 *
394 * @param years the amount
395 * @param months the amount
396 * @param days the amount
397 */
398 private static Period create(int years, int months, int days) {
399 if ((years | months | days) == 0) {
400 return ZERO;
401 }
402 return new Period(years, months, days);
403 }
404
405 /**
406 * Constructor.
407 *
408 * @param years the amount
409 * @param months the amount
410 * @param days the amount
411 */
412 private Period(int years, int months, int days) {
413 this.years = years;
414 this.months = months;
415 this.days = days;
416 }
417
418 //-----------------------------------------------------------------------
419 /**
420 * Gets the value of the requested unit.
421 * <p>
422 * This returns a value for each of the three supported units,
423 * {@link ChronoUnit#YEARS YEARS}, {@link ChronoUnit#MONTHS MONTHS} and
424 * {@link ChronoUnit#DAYS DAYS}.
425 * All other units throw an exception.
426 *
427 * @param unit the {@code TemporalUnit} for which to return the value
428 * @return the long value of the unit
429 * @throws DateTimeException if the unit is not supported
430 * @throws UnsupportedTemporalTypeException if the unit is not supported
431 */
432 @Override
433 public long get(TemporalUnit unit) {
434 if (unit == ChronoUnit.YEARS) {
435 return getYears();
436 } else if (unit == ChronoUnit.MONTHS) {
437 return getMonths();
438 } else if (unit == ChronoUnit.DAYS) {
439 return getDays();
440 } else {
441 throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
442 }
443 }
444
445 /**
446 * Gets the set of units supported by this period.
447 * <p>
448 * The supported units are {@link ChronoUnit#YEARS YEARS},
449 * {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS}.
450 * They are returned in the order years, months, days.
451 * <p>
452 * This set can be used in conjunction with {@link #get(TemporalUnit)}
453 * to access the entire state of the period.
454 *
455 * @return a list containing the years, months and days units, not null
456 */
457 @Override
458 public List<TemporalUnit> getUnits() {
459 return SUPPORTED_UNITS;
460 }
461
462 /**
463 * Gets the chronology of this period, which is the ISO calendar system.
464 * <p>
465 * The {@code Chronology} represents the calendar system in use.
466 * The ISO-8601 calendar system is the modern civil calendar system used today
467 * in most of the world. It is equivalent to the proleptic Gregorian calendar
468 * system, in which today's rules for leap years are applied for all time.
469 *
470 * @return the ISO chronology, not null
471 */
472 @Override
473 public IsoChronology getChronology() {
474 return IsoChronology.INSTANCE;
475 }
476
477 //-----------------------------------------------------------------------
478 /**
479 * Checks if all three units of this period are zero.
480 * <p>
481 * A zero period has the value zero for the years, months and days units.
482 *
483 * @return true if this period is zero-length
484 */
485 public boolean isZero() {
486 return (this == ZERO);
487 }
488
489 /**
490 * Checks if any of the three units of this period are negative.
491 * <p>
492 * This checks whether the years, months or days units are less than zero.
493 *
494 * @return true if any unit of this period is negative
495 */
496 public boolean isNegative() {
497 return years < 0 || months < 0 || days < 0;
498 }
499
500 //-----------------------------------------------------------------------
501 /**
502 * Gets the amount of years of this period.
503 * <p>
504 * This returns the years unit.
505 * <p>
506 * The months unit is not automatically normalized with the years unit.
507 * This means that a period of "15 months" is different to a period
508 * of "1 year and 3 months".
509 *
510 * @return the amount of years of this period, may be negative
511 */
512 public int getYears() {
513 return years;
514 }
515
516 /**
517 * Gets the amount of months of this period.
518 * <p>
519 * This returns the months unit.
520 * <p>
521 * The months unit is not automatically normalized with the years unit.
522 * This means that a period of "15 months" is different to a period
523 * of "1 year and 3 months".
524 *
525 * @return the amount of months of this period, may be negative
526 */
527 public int getMonths() {
528 return months;
529 }
530
531 /**
532 * Gets the amount of days of this period.
533 * <p>
534 * This returns the days unit.
535 *
536 * @return the amount of days of this period, may be negative
537 */
538 public int getDays() {
539 return days;
540 }
541
542 //-----------------------------------------------------------------------
543 /**
544 * Returns a copy of this period with the specified amount of years.
545 * <p>
546 * This sets the amount of the years unit in a copy of this period.
547 * The months and days units are unaffected.
548 * <p>
549 * The months unit is not automatically normalized with the years unit.
550 * This means that a period of "15 months" is different to a period
551 * of "1 year and 3 months".
552 * <p>
553 * This instance is immutable and unaffected by this method call.
554 *
555 * @param years the years to represent, may be negative
556 * @return a {@code Period} based on this period with the requested years, not null
557 */
558 public Period withYears(int years) {
559 if (years == this.years) {
560 return this;
561 }
562 return create(years, months, days);
563 }
564
565 /**
566 * Returns a copy of this period with the specified amount of months.
567 * <p>
568 * This sets the amount of the months unit in a copy of this period.
569 * The years and days units are unaffected.
570 * <p>
571 * The months unit is not automatically normalized with the years unit.
572 * This means that a period of "15 months" is different to a period
573 * of "1 year and 3 months".
574 * <p>
575 * This instance is immutable and unaffected by this method call.
576 *
577 * @param months the months to represent, may be negative
578 * @return a {@code Period} based on this period with the requested months, not null
579 */
580 public Period withMonths(int months) {
581 if (months == this.months) {
582 return this;
583 }
584 return create(years, months, days);
585 }
586
587 /**
588 * Returns a copy of this period with the specified amount of days.
589 * <p>
590 * This sets the amount of the days unit in a copy of this period.
591 * The years and months units are unaffected.
592 * <p>
593 * This instance is immutable and unaffected by this method call.
594 *
595 * @param days the days to represent, may be negative
596 * @return a {@code Period} based on this period with the requested days, not null
597 */
598 public Period withDays(int days) {
599 if (days == this.days) {
600 return this;
601 }
602 return create(years, months, days);
603 }
604
605 //-----------------------------------------------------------------------
606 /**
607 * Returns a copy of this period with the specified period added.
608 * <p>
609 * This operates separately on the years, months and days.
610 * No normalization is performed.
611 * <p>
612 * For example, "1 year, 6 months and 3 days" plus "2 years, 2 months and 2 days"
613 * returns "3 years, 8 months and 5 days".
614 * <p>
615 * The specified amount is typically an instance of {@code Period}.
616 * Other types are interpreted using {@link Period#from(TemporalAmount)}.
617 * <p>
618 * This instance is immutable and unaffected by this method call.
619 *
620 * @param amountToAdd the amount to add, not null
621 * @return a {@code Period} based on this period with the requested period added, not null
622 * @throws DateTimeException if the specified amount has a non-ISO chronology or
623 * contains an invalid unit
624 * @throws ArithmeticException if numeric overflow occurs
625 */
626 public Period plus(TemporalAmount amountToAdd) {
627 Period isoAmount = Period.from(amountToAdd);
628 return create(
629 Math.addExact(years, isoAmount.years),
630 Math.addExact(months, isoAmount.months),
631 Math.addExact(days, isoAmount.days));
632 }
633
634 /**
635 * Returns a copy of this period with the specified years added.
636 * <p>
637 * This adds the amount to the years unit in a copy of this period.
638 * The months and days units are unaffected.
639 * For example, "1 year, 6 months and 3 days" plus 2 years returns "3 years, 6 months and 3 days".
640 * <p>
641 * This instance is immutable and unaffected by this method call.
642 *
643 * @param yearsToAdd the years to add, positive or negative
644 * @return a {@code Period} based on this period with the specified years added, not null
645 * @throws ArithmeticException if numeric overflow occurs
646 */
647 public Period plusYears(long yearsToAdd) {
648 if (yearsToAdd == 0) {
649 return this;
650 }
651 return create(Math.toIntExact(Math.addExact(years, yearsToAdd)), months, days);
652 }
653
654 /**
655 * Returns a copy of this period with the specified months added.
656 * <p>
657 * This adds the amount to the months unit in a copy of this period.
658 * The years and days units are unaffected.
659 * For example, "1 year, 6 months and 3 days" plus 2 months returns "1 year, 8 months and 3 days".
660 * <p>
661 * This instance is immutable and unaffected by this method call.
662 *
663 * @param monthsToAdd the months to add, positive or negative
664 * @return a {@code Period} based on this period with the specified months added, not null
665 * @throws ArithmeticException if numeric overflow occurs
666 */
667 public Period plusMonths(long monthsToAdd) {
668 if (monthsToAdd == 0) {
669 return this;
670 }
671 return create(years, Math.toIntExact(Math.addExact(months, monthsToAdd)), days);
672 }
673
674 /**
675 * Returns a copy of this period with the specified days added.
676 * <p>
677 * This adds the amount to the days unit in a copy of this period.
678 * The years and months units are unaffected.
679 * For example, "1 year, 6 months and 3 days" plus 2 days returns "1 year, 6 months and 5 days".
680 * <p>
681 * This instance is immutable and unaffected by this method call.
682 *
683 * @param daysToAdd the days to add, positive or negative
684 * @return a {@code Period} based on this period with the specified days added, not null
685 * @throws ArithmeticException if numeric overflow occurs
686 */
687 public Period plusDays(long daysToAdd) {
688 if (daysToAdd == 0) {
689 return this;
690 }
691 return create(years, months, Math.toIntExact(Math.addExact(days, daysToAdd)));
692 }
693
694 //-----------------------------------------------------------------------
695 /**
696 * Returns a copy of this period with the specified period subtracted.
697 * <p>
698 * This operates separately on the years, months and days.
699 * No normalization is performed.
700 * <p>
701 * For example, "1 year, 6 months and 3 days" minus "2 years, 2 months and 2 days"
702 * returns "-1 years, 4 months and 1 day".
703 * <p>
704 * The specified amount is typically an instance of {@code Period}.
705 * Other types are interpreted using {@link Period#from(TemporalAmount)}.
706 * <p>
707 * This instance is immutable and unaffected by this method call.
708 *
709 * @param amountToSubtract the amount to subtract, not null
710 * @return a {@code Period} based on this period with the requested period subtracted, not null
711 * @throws DateTimeException if the specified amount has a non-ISO chronology or
712 * contains an invalid unit
713 * @throws ArithmeticException if numeric overflow occurs
714 */
715 public Period minus(TemporalAmount amountToSubtract) {
716 Period isoAmount = Period.from(amountToSubtract);
717 return create(
718 Math.subtractExact(years, isoAmount.years),
719 Math.subtractExact(months, isoAmount.months),
720 Math.subtractExact(days, isoAmount.days));
721 }
722
723 /**
724 * Returns a copy of this period with the specified years subtracted.
725 * <p>
726 * This subtracts the amount from the years unit in a copy of this period.
727 * The months and days units are unaffected.
728 * For example, "1 year, 6 months and 3 days" minus 2 years returns "-1 years, 6 months and 3 days".
729 * <p>
730 * This instance is immutable and unaffected by this method call.
731 *
732 * @param yearsToSubtract the years to subtract, positive or negative
733 * @return a {@code Period} based on this period with the specified years subtracted, not null
734 * @throws ArithmeticException if numeric overflow occurs
735 */
736 public Period minusYears(long yearsToSubtract) {
737 return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract));
738 }
739
740 /**
741 * Returns a copy of this period with the specified months subtracted.
742 * <p>
743 * This subtracts the amount from the months unit in a copy of this period.
744 * The years and days units are unaffected.
745 * For example, "1 year, 6 months and 3 days" minus 2 months returns "1 year, 4 months and 3 days".
746 * <p>
747 * This instance is immutable and unaffected by this method call.
748 *
749 * @param monthsToSubtract the years to subtract, positive or negative
750 * @return a {@code Period} based on this period with the specified months subtracted, not null
751 * @throws ArithmeticException if numeric overflow occurs
752 */
753 public Period minusMonths(long monthsToSubtract) {
754 return (monthsToSubtract == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-monthsToSubtract));
755 }
756
757 /**
758 * Returns a copy of this period with the specified days subtracted.
759 * <p>
760 * This subtracts the amount from the days unit in a copy of this period.
761 * The years and months units are unaffected.
762 * For example, "1 year, 6 months and 3 days" minus 2 days returns "1 year, 6 months and 1 day".
763 * <p>
764 * This instance is immutable and unaffected by this method call.
765 *
766 * @param daysToSubtract the months to subtract, positive or negative
767 * @return a {@code Period} based on this period with the specified days subtracted, not null
768 * @throws ArithmeticException if numeric overflow occurs
769 */
770 public Period minusDays(long daysToSubtract) {
771 return (daysToSubtract == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-daysToSubtract));
772 }
773
774 //-----------------------------------------------------------------------
775 /**
776 * Returns a new instance with each element in this period multiplied
777 * by the specified scalar.
778 * <p>
779 * This returns a period with each of the years, months and days units
780 * individually multiplied.
781 * For example, a period of "2 years, -3 months and 4 days" multiplied by
782 * 3 will return "6 years, -9 months and 12 days".
783 * No normalization is performed.
784 *
785 * @param scalar the scalar to multiply by, not null
786 * @return a {@code Period} based on this period with the amounts multiplied by the scalar, not null
787 * @throws ArithmeticException if numeric overflow occurs
788 */
789 public Period multipliedBy(int scalar) {
790 if (this == ZERO || scalar == 1) {
791 return this;
792 }
793 return create(
794 Math.multiplyExact(years, scalar),
795 Math.multiplyExact(months, scalar),
796 Math.multiplyExact(days, scalar));
797 }
798
799 /**
800 * Returns a new instance with each amount in this period negated.
801 * <p>
802 * This returns a period with each of the years, months and days units
803 * individually negated.
804 * For example, a period of "2 years, -3 months and 4 days" will be
805 * negated to "-2 years, 3 months and -4 days".
806 * No normalization is performed.
807 *
808 * @return a {@code Period} based on this period with the amounts negated, not null
809 * @throws ArithmeticException if numeric overflow occurs, which only happens if
810 * one of the units has the value {@code Long.MIN_VALUE}
811 */
812 public Period negated() {
813 return multipliedBy(-1);
814 }
815
816 //-----------------------------------------------------------------------
817 /**
818 * Returns a copy of this period with the years and months normalized.
819 * <p>
820 * This normalizes the years and months units, leaving the days unit unchanged.
821 * The months unit is adjusted to have an absolute value less than 12,
822 * with the years unit being adjusted to compensate. For example, a period of
823 * "1 Year and 15 months" will be normalized to "2 years and 3 months".
824 * <p>
825 * The sign of the years and months units will be the same after normalization.
826 * For example, a period of "1 year and -25 months" will be normalized to
827 * "-1 year and -1 month".
828 * <p>
829 * This instance is immutable and unaffected by this method call.
830 *
831 * @return a {@code Period} based on this period with excess months normalized to years, not null
832 * @throws ArithmeticException if numeric overflow occurs
833 */
834 public Period normalized() {
835 long totalMonths = toTotalMonths();
836 long splitYears = totalMonths / 12;
837 int splitMonths = (int) (totalMonths % 12); // no overflow
838 if (splitYears == years && splitMonths == months) {
839 return this;
840 }
841 return create(Math.toIntExact(splitYears), splitMonths, days);
842 }
843
844 /**
845 * Gets the total number of months in this period.
846 * <p>
847 * This returns the total number of months in the period by multiplying the
848 * number of years by 12 and adding the number of months.
849 * <p>
850 * This instance is immutable and unaffected by this method call.
851 *
852 * @return the total number of months in the period, may be negative
853 */
854 public long toTotalMonths() {
855 return years * 12L + months; // no overflow
856 }
857
858 //-------------------------------------------------------------------------
859 /**
860 * Adds this period to the specified temporal object.
861 * <p>
862 * This returns a temporal object of the same observable type as the input
863 * with this period added.
864 * If the temporal has a chronology, it must be the ISO chronology.
865 * <p>
866 * In most cases, it is clearer to reverse the calling pattern by using
867 * {@link Temporal#plus(TemporalAmount)}.
868 * <pre>
869 * // these two lines are equivalent, but the second approach is recommended
870 * dateTime = thisPeriod.addTo(dateTime);
871 * dateTime = dateTime.plus(thisPeriod);
872 * </pre>
873 * <p>
874 * The calculation operates as follows.
875 * First, the chronology of the temporal is checked to ensure it is ISO chronology or null.
876 * Second, if the months are zero, the years are added if non-zero, otherwise
877 * the combination of years and months is added if non-zero.
878 * Finally, any days are added.
879 * <p>
880 * This approach ensures that a partial period can be added to a partial date.
881 * For example, a period of years and/or months can be added to a {@code YearMonth},
882 * but a period including days cannot.
883 * The approach also adds years and months together when necessary, which ensures
884 * correct behaviour at the end of the month.
885 * <p>
886 * This instance is immutable and unaffected by this method call.
887 *
888 * @param temporal the temporal object to adjust, not null
889 * @return an object of the same type with the adjustment made, not null
890 * @throws DateTimeException if unable to add
891 * @throws ArithmeticException if numeric overflow occurs
892 */
893 @Override
894 public Temporal addTo(Temporal temporal) {
895 validateChrono(temporal);
896 if (months == 0) {
897 if (years != 0) {
898 temporal = temporal.plus(years, YEARS);
899 }
900 } else {
901 long totalMonths = toTotalMonths();
902 if (totalMonths != 0) {
903 temporal = temporal.plus(totalMonths, MONTHS);
904 }
905 }
906 if (days != 0) {
907 temporal = temporal.plus(days, DAYS);
908 }
909 return temporal;
910 }
911
912 /**
913 * Subtracts this period from the specified temporal object.
914 * <p>
915 * This returns a temporal object of the same observable type as the input
916 * with this period subtracted.
917 * If the temporal has a chronology, it must be the ISO chronology.
918 * <p>
919 * In most cases, it is clearer to reverse the calling pattern by using
920 * {@link Temporal#minus(TemporalAmount)}.
921 * <pre>
922 * // these two lines are equivalent, but the second approach is recommended
923 * dateTime = thisPeriod.subtractFrom(dateTime);
924 * dateTime = dateTime.minus(thisPeriod);
925 * </pre>
926 * <p>
927 * The calculation operates as follows.
928 * First, the chronology of the temporal is checked to ensure it is ISO chronology or null.
929 * Second, if the months are zero, the years are subtracted if non-zero, otherwise
930 * the combination of years and months is subtracted if non-zero.
931 * Finally, any days are subtracted.
932 * <p>
933 * This approach ensures that a partial period can be subtracted from a partial date.
934 * For example, a period of years and/or months can be subtracted from a {@code YearMonth},
935 * but a period including days cannot.
936 * The approach also subtracts years and months together when necessary, which ensures
937 * correct behaviour at the end of the month.
938 * <p>
939 * This instance is immutable and unaffected by this method call.
940 *
941 * @param temporal the temporal object to adjust, not null
942 * @return an object of the same type with the adjustment made, not null
943 * @throws DateTimeException if unable to subtract
944 * @throws ArithmeticException if numeric overflow occurs
945 */
946 @Override
947 public Temporal subtractFrom(Temporal temporal) {
948 validateChrono(temporal);
949 if (months == 0) {
950 if (years != 0) {
951 temporal = temporal.minus(years, YEARS);
952 }
953 } else {
954 long totalMonths = toTotalMonths();
955 if (totalMonths != 0) {
956 temporal = temporal.minus(totalMonths, MONTHS);
957 }
958 }
959 if (days != 0) {
960 temporal = temporal.minus(days, DAYS);
961 }
962 return temporal;
963 }
964
965 /**
966 * Validates that the temporal has the correct chronology.
967 */
968 private void validateChrono(TemporalAccessor temporal) {
969 Objects.requireNonNull(temporal, "temporal");
970 Chronology temporalChrono = temporal.query(TemporalQueries.chronology());
971 if (temporalChrono != null && IsoChronology.INSTANCE.equals(temporalChrono) == false) {
972 throw new DateTimeException("Chronology mismatch, expected: ISO, actual: " + temporalChrono.getId());
973 }
974 }
975
976 //-----------------------------------------------------------------------
977 /**
978 * Checks if this period is equal to another period.
979 * <p>
980 * The comparison is based on the type {@code Period} and each of the three amounts.
981 * To be equal, the years, months and days units must be individually equal.
982 * Note that this means that a period of "15 Months" is not equal to a period
983 * of "1 Year and 3 Months".
984 *
985 * @param obj the object to check, null returns false
986 * @return true if this is equal to the other period
987 */
988 @Override
989 public boolean equals(Object obj) {
990 if (this == obj) {
991 return true;
992 }
993 if (obj instanceof Period) {
994 Period other = (Period) obj;
995 return years == other.years &&
996 months == other.months &&
997 days == other.days;
998 }
999 return false;
1000 }
1001
1002 /**
1003 * A hash code for this period.
1004 *
1005 * @return a suitable hash code
1006 */
1007 @Override
1008 public int hashCode() {
1009 return years + Integer.rotateLeft(months, 8) + Integer.rotateLeft(days, 16);
1010 }
1011
1012 //-----------------------------------------------------------------------
1013 /**
1014 * Outputs this period as a {@code String}, such as {@code P6Y3M1D}.
1015 * <p>
1016 * The output will be in the ISO-8601 period format.
1017 * A zero period will be represented as zero days, 'P0D'.
1018 *
1019 * @return a string representation of this period, not null
1020 */
1021 @Override
1022 public String toString() {
1023 if (this == ZERO) {
1024 return "P0D";
1025 } else {
1026 StringBuilder buf = new StringBuilder();
1027 buf.append('P');
1028 if (years != 0) {
1029 buf.append(years).append('Y');
1030 }
1031 if (months != 0) {
1032 buf.append(months).append('M');
1033 }
1034 if (days != 0) {
1035 buf.append(days).append('D');
1036 }
1037 return buf.toString();
1038 }
1039 }
1040
1041 //-----------------------------------------------------------------------
1042 /**
1043 * Writes the object using a
1044 * <a href="../../serialized-form.html#java.time.Ser">dedicated serialized form</a>.
1045 * @serialData
1046 * <pre>
1047 * out.writeByte(14); // identifies a Period
1048 * out.writeInt(years);
1049 * out.writeInt(months);
1050 * out.writeInt(days);
1051 * </pre>
1052 *
1053 * @return the instance of {@code Ser}, not null
1054 */
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 private void readObject(ObjectInputStream s) throws InvalidObjectException {
1066 throw new InvalidObjectException("Deserialization via serialization delegate");
1067 }
1068
1069 void writeExternal(DataOutput out) throws IOException {
1070 out.writeInt(years);
1071 out.writeInt(months);
1072 out.writeInt(days);
1073 }
1074
1075 static Period readExternal(DataInput in) throws IOException {
1076 int years = in.readInt();
1077 int months = in.readInt();
1078 int days = in.readInt();
1079 return Period.of(years, months, days);
1080 }
1081
1082 }