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.ChronoField.MONTH_OF_YEAR;
65 import static java.time.temporal.ChronoUnit.DAYS;
66 import static java.time.temporal.ChronoUnit.MONTHS;
67 import static java.time.temporal.ChronoUnit.YEARS;
68
69 import java.io.DataInput;
70 import java.io.DataOutput;
71 import java.io.IOException;
72 import java.io.InvalidObjectException;
73 import java.io.ObjectStreamException;
74 import java.io.Serializable;
75 import java.time.chrono.ChronoLocalDate;
76 import java.time.chrono.Chronology;
77 import java.time.format.DateTimeParseException;
78 import java.time.temporal.ChronoUnit;
79 import java.time.temporal.Temporal;
80 import java.time.temporal.TemporalAmount;
81 import java.time.temporal.TemporalUnit;
82 import java.time.temporal.ValueRange;
83 import java.util.Arrays;
84 import java.util.Collections;
85 import java.util.List;
86 import java.util.Objects;
87 import java.util.regex.Matcher;
88 import java.util.regex.Pattern;
89
90 /**
91 * A date-based amount of time, such as '2 years, 3 months and 4 days'.
92 * <p>
93 * This class models a quantity or amount of time in terms of years, months and days.
94 * See {@link Duration} for the time-based equivalent to this class.
95 * <p>
96 * Durations and period differ in their treatment of daylight savings time
97 * when added to {@link ZonedDateTime}. A {@code Duration} will add an exact
98 * number of seconds, thus a duration of one day is always exactly 24 hours.
99 * By contrast, a {@code Period} will add a conceptual day, trying to maintain
100 * the local time.
101 * <p>
102 * For example, consider adding a period of one day and a duration of one day to
103 * 18:00 on the evening before a daylight savings gap. The {@code Period} will add
104 * the conceptual day and result in a {@code ZonedDateTime} at 18:00 the following day.
105 * By contrast, the {@code Duration} will add exactly 24 hours, resulting in a
106 * {@code ZonedDateTime} at 19:00 the following day (assuming a one hour DST gap).
107 * <p>
108 * The supported units of a period are {@link ChronoUnit#YEARS YEARS},
109 * {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS}.
110 * All three fields are always present, but may be set to zero.
111 * <p>
112 * The period may be used with any calendar system.
113 * The meaning of a "year" or "month" is only applied when the object is added to a date.
114 * <p>
115 * The period is modeled as a directed amount of time, meaning that individual parts of the
116 * period may be negative.
117 * <p>
118 * The months and years fields may be {@linkplain #normalized() normalized}.
119 * The normalization assumes a 12 month year, so is not appropriate for all calendar systems.
120 *
121 * <h3>Specification for implementors</h3>
122 * This class is immutable and thread-safe.
123 *
124 * @since 1.8
125 */
126 public final class Period
127 implements TemporalAmount, Serializable {
128
129 /**
130 * A constant for a period of zero.
131 */
132 public static final Period ZERO = new Period(0, 0, 0);
133 /**
134 * Serialization version.
135 */
136 private static final long serialVersionUID = -3587258372562876L;
137 /**
138 * The pattern for parsing.
139 */
140 private final static Pattern PATTERN =
141 Pattern.compile("([-+]?)P(?:([-+]?[0-9]+)Y)?(?:([-+]?[0-9]+)M)?(?:([-+]?[0-9]+)D)?", Pattern.CASE_INSENSITIVE);
142 /**
143 * The set of supported units.
144 */
145 private final static List<TemporalUnit> SUPPORTED_UNITS =
146 Collections.unmodifiableList(Arrays.<TemporalUnit>asList(YEARS, MONTHS, DAYS));
147
148 /**
149 * The number of years.
150 */
151 private final int years;
152 /**
153 * The number of months.
154 */
155 private final int months;
156 /**
157 * The number of days.
158 */
159 private final int days;
160
161 //-----------------------------------------------------------------------
162 /**
163 * Obtains a {@code Period} representing a number of years.
164 * <p>
165 * The resulting period will have the specified years.
166 * The months and days units will be zero.
167 *
168 * @param years the number of years, positive or negative
169 * @return the period of years, not null
170 */
171 public static Period ofYears(int years) {
172 return create(years, 0, 0);
173 }
174
175 /**
176 * Obtains a {@code Period} representing a number of months.
177 * <p>
178 * The resulting period will have the specified months.
179 * The years and days units will be zero.
180 *
181 * @param months the number of months, positive or negative
182 * @return the period of months, not null
183 */
184 public static Period ofMonths(int months) {
185 return create(0, months, 0);
186 }
187
188 /**
189 * Obtains a {@code Period} representing a number of days.
190 * <p>
191 * The resulting period will have the specified days.
192 * The years and months units will be zero.
193 *
194 * @param days the number of days, positive or negative
195 * @return the period of days, not null
196 */
197 public static Period ofDays(int days) {
198 return create(0, 0, days);
199 }
200
201 //-----------------------------------------------------------------------
202 /**
203 * Obtains a {@code Period} representing a number of years, months and days.
204 * <p>
205 * This creates an instance based on years, months and days.
206 *
207 * @param years the amount of years, may be negative
208 * @param months the amount of months, may be negative
209 * @param days the amount of days, may be negative
210 * @return the period of years, months and days, not null
211 */
212 public static Period of(int years, int months, int days) {
213 return create(years, months, days);
214 }
215
216 //-----------------------------------------------------------------------
217 /**
218 * Obtains a {@code Period} consisting of the number of years, months,
219 * and days between two dates.
220 * <p>
221 * The start date is included, but the end date is not.
222 * The period is calculated by removing complete months, then calculating
223 * the remaining number of days, adjusting to ensure that both have the same sign.
224 * The number of months is then split into years and months based on a 12 month year.
225 * A month is considered if the end day-of-month is greater than or equal to the start day-of-month.
226 * For example, from {@code 2010-01-15} to {@code 2011-03-18} is one year, two months and three days.
227 * <p>
228 * The result of this method can be a negative period if the end is before the start.
229 * The negative sign will be the same in each of year, month and day.
230 *
231 * @param startDate the start date, inclusive, not null
232 * @param endDate the end date, exclusive, not null
233 * @return the period between this date and the end date, not null
234 * @see ChronoLocalDate#periodUntil(ChronoLocalDate)
235 */
236 public static Period between(LocalDate startDate, LocalDate endDate) {
237 return startDate.periodUntil(endDate);
238 }
239
240 //-----------------------------------------------------------------------
241 /**
242 * Obtains a {@code Period} from a text string such as {@code PnYnMnD}.
243 * <p>
244 * This will parse the string produced by {@code toString()} which is
245 * based on the ISO-8601 period format {@code PnYnMnD}.
246 * <p>
247 * The string starts with an optional sign, denoted by the ASCII negative
248 * or positive symbol. If negative, the whole period is negated.
249 * The ASCII letter "P" is next in upper or lower case.
250 * There are then three sections, each consisting of a number and a suffix.
251 * At least one of the three sections must be present.
252 * The sections have suffixes in ASCII of "Y", "M" and "D" for
253 * years, months and days, accepted in upper or lower case.
254 * The suffixes must occur in order.
255 * The number part of each section must consist of ASCII digits.
256 * The number may be prefixed by the ASCII negative or positive symbol.
257 * The number must parse to an {@code int}.
258 * <p>
259 * The leading plus/minus sign, and negative values for other units are
260 * not part of the ISO-8601 standard.
261 *
262 * @param text the text to parse, not null
263 * @return the parsed period, not null
264 * @throws DateTimeParseException if the text cannot be parsed to a period
265 */
266 public static Period parse(CharSequence text) {
267 Objects.requireNonNull(text, "text");
268 Matcher matcher = PATTERN.matcher(text);
269 if (matcher.matches()) {
270 int negate = ("-".equals(matcher.group(1)) ? -1 : 1);
271 String yearMatch = matcher.group(2);
272 String monthMatch = matcher.group(3);
273 String dayMatch = matcher.group(4);
274 if (yearMatch != null || monthMatch != null || dayMatch != null) {
275 try {
276 return create(parseNumber(text, yearMatch, negate),
277 parseNumber(text, monthMatch, negate),
278 parseNumber(text, dayMatch, negate));
279 } catch (NumberFormatException ex) {
280 throw (DateTimeParseException) new DateTimeParseException("Text cannot be parsed to a Period", text, 0).initCause(ex);
281 }
282 }
283 }
284 throw new DateTimeParseException("Text cannot be parsed to a Period", text, 0);
285 }
286
287 private static int parseNumber(CharSequence text, String str, int negate) {
288 if (str == null) {
289 return 0;
290 }
291 int val = Integer.parseInt(str);
292 try {
293 return Math.multiplyExact(val, negate);
294 } catch (ArithmeticException ex) {
295 throw (DateTimeParseException) new DateTimeParseException("Text cannot be parsed to a Period", text, 0).initCause(ex);
296 }
297 }
298
299 //-----------------------------------------------------------------------
300 /**
301 * Creates an instance.
302 *
303 * @param years the amount
304 * @param months the amount
305 * @param days the amount
306 */
307 private static Period create(int years, int months, int days) {
308 if ((years | months | days) == 0) {
309 return ZERO;
310 }
311 return new Period(years, months, days);
312 }
313
314 /**
315 * Constructor.
316 *
317 * @param years the amount
318 * @param months the amount
319 * @param days the amount
320 */
321 private Period(int years, int months, int days) {
322 this.years = years;
323 this.months = months;
324 this.days = days;
325 }
326
327 //-----------------------------------------------------------------------
328 /**
329 * Gets the value of the requested unit.
330 * <p>
331 * This returns a value for each of the three supported units,
332 * {@link ChronoUnit#YEARS YEARS}, {@link ChronoUnit#MONTHS MONTHS} and
333 * {@link ChronoUnit#DAYS DAYS}.
334 * All other units throw an exception.
335 *
336 * @param unit the {@code TemporalUnit} for which to return the value
337 * @return the long value of the unit
338 * @throws DateTimeException if the unit is not supported
339 */
340 @Override
341 public long get(TemporalUnit unit) {
342 if (unit == ChronoUnit.YEARS) {
343 return getYears();
344 } else if (unit == ChronoUnit.MONTHS) {
345 return getMonths();
346 } else if (unit == ChronoUnit.DAYS) {
347 return getDays();
348 } else {
349 throw new DateTimeException("Unsupported unit: " + unit.getName());
350 }
351 }
352
353 /**
354 * Gets the set of units supported by this period.
355 * <p>
356 * The supported units are {@link ChronoUnit#YEARS YEARS},
357 * {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS}.
358 * They are returned in the order years, months, days.
359 * <p>
360 * This set can be used in conjunction with {@link #get(TemporalUnit)}
361 * to access the entire state of the period.
362 *
363 * @return a list containing the years, months and days units, not null
364 */
365 @Override
366 public List<TemporalUnit> getUnits() {
367 return SUPPORTED_UNITS;
368 }
369
370 //-----------------------------------------------------------------------
371 /**
372 * Checks if all three units of this period are zero.
373 * <p>
374 * A zero period has the value zero for the years, months and days units.
375 *
376 * @return true if this period is zero-length
377 */
378 public boolean isZero() {
379 return (this == ZERO);
380 }
381
382 /**
383 * Checks if any of the three units of this period are negative.
384 * <p>
385 * This checks whether the years, months or days units are less than zero.
386 *
387 * @return true if any unit of this period is negative
388 */
389 public boolean isNegative() {
390 return years < 0 || months < 0 || days < 0;
391 }
392
393 //-----------------------------------------------------------------------
394 /**
395 * Gets the amount of years of this period.
396 * <p>
397 * This returns the years unit.
398 * <p>
399 * The months unit is not normalized with the years unit.
400 * This means that a period of "15 months" is different to a period
401 * of "1 year and 3 months".
402 *
403 * @return the amount of years of this period, may be negative
404 */
405 public int getYears() {
406 return years;
407 }
408
409 /**
410 * Gets the amount of months of this period.
411 * <p>
412 * This returns the months unit.
413 * <p>
414 * The months unit is not normalized with the years unit.
415 * This means that a period of "15 months" is different to a period
416 * of "1 year and 3 months".
417 *
418 * @return the amount of months of this period, may be negative
419 */
420 public int getMonths() {
421 return months;
422 }
423
424 /**
425 * Gets the amount of days of this period.
426 * <p>
427 * This returns the days unit.
428 *
429 * @return the amount of days of this period, may be negative
430 */
431 public int getDays() {
432 return days;
433 }
434
435 //-----------------------------------------------------------------------
436 /**
437 * Returns a copy of this period with the specified amount of years.
438 * <p>
439 * This sets the amount of the years unit in a copy of this period.
440 * The months and days units are unaffected.
441 * <p>
442 * The months unit is not normalized with the years unit.
443 * This means that a period of "15 months" is different to a period
444 * of "1 year and 3 months".
445 * <p>
446 * This instance is immutable and unaffected by this method call.
447 *
448 * @param years the years to represent, may be negative
449 * @return a {@code Period} based on this period with the requested years, not null
450 */
451 public Period withYears(int years) {
452 if (years == this.years) {
453 return this;
454 }
455 return create(years, months, days);
456 }
457
458 /**
459 * Returns a copy of this period with the specified amount of months.
460 * <p>
461 * This sets the amount of the months unit in a copy of this period.
462 * The years and days units are unaffected.
463 * <p>
464 * The months unit is not normalized with the years unit.
465 * This means that a period of "15 months" is different to a period
466 * of "1 year and 3 months".
467 * <p>
468 * This instance is immutable and unaffected by this method call.
469 *
470 * @param months the months to represent, may be negative
471 * @return a {@code Period} based on this period with the requested months, not null
472 */
473 public Period withMonths(int months) {
474 if (months == this.months) {
475 return this;
476 }
477 return create(years, months, days);
478 }
479
480 /**
481 * Returns a copy of this period with the specified amount of days.
482 * <p>
483 * This sets the amount of the days unit in a copy of this period.
484 * The years and months units are unaffected.
485 * <p>
486 * This instance is immutable and unaffected by this method call.
487 *
488 * @param days the days to represent, may be negative
489 * @return a {@code Period} based on this period with the requested days, not null
490 */
491 public Period withDays(int days) {
492 if (days == this.days) {
493 return this;
494 }
495 return create(years, months, days);
496 }
497
498 //-----------------------------------------------------------------------
499 /**
500 * Returns a copy of this period with the specified period added.
501 * <p>
502 * This operates separately on the years, months, days and the normalized time.
503 * There is no further normalization beyond the normalized time.
504 * <p>
505 * For example, "1 year, 6 months and 3 days" plus "2 years, 2 months and 2 days"
506 * returns "3 years, 8 months and 5 days".
507 * <p>
508 * This instance is immutable and unaffected by this method call.
509 *
510 * @param amountToAdd the period to add, not null
511 * @return a {@code Period} based on this period with the requested period added, not null
512 * @throws ArithmeticException if numeric overflow occurs
513 */
514 public Period plus(Period amountToAdd) {
515 return create(
516 Math.addExact(years, amountToAdd.years),
517 Math.addExact(months, amountToAdd.months),
518 Math.addExact(days, amountToAdd.days));
519 }
520
521 /**
522 * Returns a copy of this period with the specified years added.
523 * <p>
524 * This adds the amount to the years unit in a copy of this period.
525 * The months and days units are unaffected.
526 * For example, "1 year, 6 months and 3 days" plus 2 years returns "3 years, 6 months and 3 days".
527 * <p>
528 * This instance is immutable and unaffected by this method call.
529 *
530 * @param yearsToAdd the years to add, positive or negative
531 * @return a {@code Period} based on this period with the specified years added, not null
532 * @throws ArithmeticException if numeric overflow occurs
533 */
534 public Period plusYears(long yearsToAdd) {
535 if (yearsToAdd == 0) {
536 return this;
537 }
538 return create(Math.toIntExact(Math.addExact(years, yearsToAdd)), months, days);
539 }
540
541 /**
542 * Returns a copy of this period with the specified months added.
543 * <p>
544 * This adds the amount to the months unit in a copy of this period.
545 * The years and days units are unaffected.
546 * For example, "1 year, 6 months and 3 days" plus 2 months returns "1 year, 8 months and 3 days".
547 * <p>
548 * This instance is immutable and unaffected by this method call.
549 *
550 * @param monthsToAdd the months to add, positive or negative
551 * @return a {@code Period} based on this period with the specified months added, not null
552 * @throws ArithmeticException if numeric overflow occurs
553 */
554 public Period plusMonths(long monthsToAdd) {
555 if (monthsToAdd == 0) {
556 return this;
557 }
558 return create(years, Math.toIntExact(Math.addExact(months, monthsToAdd)), days);
559 }
560
561 /**
562 * Returns a copy of this period with the specified days added.
563 * <p>
564 * This adds the amount to the days unit in a copy of this period.
565 * The years and months units are unaffected.
566 * For example, "1 year, 6 months and 3 days" plus 2 days returns "1 year, 6 months and 5 days".
567 * <p>
568 * This instance is immutable and unaffected by this method call.
569 *
570 * @param daysToAdd the days to add, positive or negative
571 * @return a {@code Period} based on this period with the specified days added, not null
572 * @throws ArithmeticException if numeric overflow occurs
573 */
574 public Period plusDays(long daysToAdd) {
575 if (daysToAdd == 0) {
576 return this;
577 }
578 return create(years, months, Math.toIntExact(Math.addExact(days, daysToAdd)));
579 }
580
581 //-----------------------------------------------------------------------
582 /**
583 * Returns a copy of this period with the specified period subtracted.
584 * <p>
585 * This operates separately on the years, months, days and the normalized time.
586 * There is no further normalization beyond the normalized time.
587 * <p>
588 * For example, "1 year, 6 months and 3 days" minus "2 years, 2 months and 2 days"
589 * returns "-1 years, 4 months and 1 day".
590 * <p>
591 * This instance is immutable and unaffected by this method call.
592 *
593 * @param amountToSubtract the period to subtract, not null
594 * @return a {@code Period} based on this period with the requested period subtracted, not null
595 * @throws ArithmeticException if numeric overflow occurs
596 */
597 public Period minus(Period amountToSubtract) {
598 return create(
599 Math.subtractExact(years, amountToSubtract.years),
600 Math.subtractExact(months, amountToSubtract.months),
601 Math.subtractExact(days, amountToSubtract.days));
602 }
603
604 /**
605 * Returns a copy of this period with the specified years subtracted.
606 * <p>
607 * This subtracts the amount from the years unit in a copy of this period.
608 * The months and days units are unaffected.
609 * For example, "1 year, 6 months and 3 days" minus 2 years returns "-1 years, 6 months and 3 days".
610 * <p>
611 * This instance is immutable and unaffected by this method call.
612 *
613 * @param yearsToSubtract the years to subtract, positive or negative
614 * @return a {@code Period} based on this period with the specified years subtracted, not null
615 * @throws ArithmeticException if numeric overflow occurs
616 */
617 public Period minusYears(long yearsToSubtract) {
618 return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract));
619 }
620
621 /**
622 * Returns a copy of this period with the specified months subtracted.
623 * <p>
624 * This subtracts the amount from the months unit in a copy of this period.
625 * The years and days units are unaffected.
626 * For example, "1 year, 6 months and 3 days" minus 2 months returns "1 year, 4 months and 3 days".
627 * <p>
628 * This instance is immutable and unaffected by this method call.
629 *
630 * @param monthsToSubtract the years to subtract, positive or negative
631 * @return a {@code Period} based on this period with the specified months subtracted, not null
632 * @throws ArithmeticException if numeric overflow occurs
633 */
634 public Period minusMonths(long monthsToSubtract) {
635 return (monthsToSubtract == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-monthsToSubtract));
636 }
637
638 /**
639 * Returns a copy of this period with the specified days subtracted.
640 * <p>
641 * This subtracts the amount from the days unit in a copy of this period.
642 * The years and months units are unaffected.
643 * For example, "1 year, 6 months and 3 days" minus 2 days returns "1 year, 6 months and 1 day".
644 * <p>
645 * This instance is immutable and unaffected by this method call.
646 *
647 * @param daysToSubtract the months to subtract, positive or negative
648 * @return a {@code Period} based on this period with the specified days subtracted, not null
649 * @throws ArithmeticException if numeric overflow occurs
650 */
651 public Period minusDays(long daysToSubtract) {
652 return (daysToSubtract == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-daysToSubtract));
653 }
654
655 //-----------------------------------------------------------------------
656 /**
657 * Returns a new instance with each element in this period multiplied
658 * by the specified scalar.
659 * <p>
660 * This returns a period with each of the years, months and days units
661 * individually multiplied.
662 * For example, a period of "2 years, -3 months and 4 days" multiplied by
663 * 3 will return "6 years, -9 months and 12 days".
664 * No normalization is performed.
665 *
666 * @param scalar the scalar to multiply by, not null
667 * @return a {@code Period} based on this period with the amounts multiplied by the scalar, not null
668 * @throws ArithmeticException if numeric overflow occurs
669 */
670 public Period multipliedBy(int scalar) {
671 if (this == ZERO || scalar == 1) {
672 return this;
673 }
674 return create(
675 Math.multiplyExact(years, scalar),
676 Math.multiplyExact(months, scalar),
677 Math.multiplyExact(days, scalar));
678 }
679
680 /**
681 * Returns a new instance with each amount in this period negated.
682 * <p>
683 * This returns a period with each of the years, months and days units
684 * individually negated.
685 * For example, a period of "2 years, -3 months and 4 days" will be
686 * negated to "-2 years, 3 months and -4 days".
687 * No normalization is performed.
688 *
689 * @return a {@code Period} based on this period with the amounts negated, not null
690 * @throws ArithmeticException if numeric overflow occurs, which only happens if
691 * one of the units has the value {@code Long.MIN_VALUE}
692 */
693 public Period negated() {
694 return multipliedBy(-1);
695 }
696
697 //-----------------------------------------------------------------------
698 /**
699 * Returns a copy of this period with the years and months normalized
700 * using a 12 month year.
701 * <p>
702 * This normalizes the years and months units, leaving the days unit unchanged.
703 * The months unit is adjusted to have an absolute value less than 11,
704 * with the years unit being adjusted to compensate. For example, a period of
705 * "1 Year and 15 months" will be normalized to "2 years and 3 months".
706 * <p>
707 * The sign of the years and months units will be the same after normalization.
708 * For example, a period of "1 year and -25 months" will be normalized to
709 * "-1 year and -1 month".
710 * <p>
711 * This normalization uses a 12 month year which is not valid for all calendar systems.
712 * <p>
713 * This instance is immutable and unaffected by this method call.
714 *
715 * @return a {@code Period} based on this period with excess months normalized to years, not null
716 * @throws ArithmeticException if numeric overflow occurs
717 */
718 public Period normalized() {
719 long totalMonths = toTotalMonths();
720 long splitYears = totalMonths / 12;
721 int splitMonths = (int) (totalMonths % 12); // no overflow
722 if (splitYears == years && splitMonths == months) {
723 return this;
724 }
725 return create(Math.toIntExact(splitYears), splitMonths, days);
726 }
727
728 /**
729 * Gets the total number of months in this period using a 12 month year.
730 * <p>
731 * This returns the total number of months in the period by multiplying the
732 * number of years by 12 and adding the number of months.
733 * <p>
734 * This uses a 12 month year which is not valid for all calendar systems.
735 * <p>
736 * This instance is immutable and unaffected by this method call.
737 *
738 * @return the total number of months in the period, may be negative
739 */
740 public long toTotalMonths() {
741 return years * 12L + months; // no overflow
742 }
743
744 //-------------------------------------------------------------------------
745 /**
746 * Adds this period to the specified temporal object.
747 * <p>
748 * This returns a temporal object of the same observable type as the input
749 * with this period added.
750 * <p>
751 * In most cases, it is clearer to reverse the calling pattern by using
752 * {@link Temporal#plus(TemporalAmount)}.
753 * <pre>
754 * // these two lines are equivalent, but the second approach is recommended
755 * dateTime = thisPeriod.addTo(dateTime);
756 * dateTime = dateTime.plus(thisPeriod);
757 * </pre>
758 * <p>
759 * The calculation will add the years, then months, then days.
760 * Only non-zero amounts will be added.
761 * If the date-time has a calendar system with a fixed number of months in a
762 * year, then the years and months will be combined before being added.
763 * <p>
764 * This instance is immutable and unaffected by this method call.
765 *
766 * @param temporal the temporal object to adjust, not null
767 * @return an object of the same type with the adjustment made, not null
768 * @throws DateTimeException if unable to add
769 * @throws ArithmeticException if numeric overflow occurs
770 */
771 @Override
772 public Temporal addTo(Temporal temporal) {
773 Objects.requireNonNull(temporal, "temporal");
774 if ((years | months) != 0) {
775 long monthRange = monthRange(temporal);
776 if (monthRange >= 0) {
777 temporal = temporal.plus(years * monthRange + months, MONTHS);
778 } else {
779 if (years != 0) {
780 temporal = temporal.plus(years, YEARS);
781 }
782 if (months != 0) {
783 temporal = temporal.plus(months, MONTHS);
784 }
785 }
786 }
787 if (days != 0) {
788 temporal = temporal.plus(days, DAYS);
789 }
790 return temporal;
791 }
792
793 /**
794 * Subtracts this period from the specified temporal object.
795 * <p>
796 * This returns a temporal object of the same observable type as the input
797 * with this period subtracted.
798 * <p>
799 * In most cases, it is clearer to reverse the calling pattern by using
800 * {@link Temporal#minus(TemporalAmount)}.
801 * <pre>
802 * // these two lines are equivalent, but the second approach is recommended
803 * dateTime = thisPeriod.subtractFrom(dateTime);
804 * dateTime = dateTime.minus(thisPeriod);
805 * </pre>
806 * <p>
807 * The calculation will subtract the years, then months, then days.
808 * Only non-zero amounts will be subtracted.
809 * If the date-time has a calendar system with a fixed number of months in a
810 * year, then the years and months will be combined before being subtracted.
811 * <p>
812 * This instance is immutable and unaffected by this method call.
813 *
814 * @param temporal the temporal object to adjust, not null
815 * @return an object of the same type with the adjustment made, not null
816 * @throws DateTimeException if unable to subtract
817 * @throws ArithmeticException if numeric overflow occurs
818 */
819 @Override
820 public Temporal subtractFrom(Temporal temporal) {
821 Objects.requireNonNull(temporal, "temporal");
822 if ((years | months) != 0) {
823 long monthRange = monthRange(temporal);
824 if (monthRange >= 0) {
825 temporal = temporal.minus(years * monthRange + months, MONTHS);
826 } else {
827 if (years != 0) {
828 temporal = temporal.minus(years, YEARS);
829 }
830 if (months != 0) {
831 temporal = temporal.minus(months, MONTHS);
832 }
833 }
834 }
835 if (days != 0) {
836 temporal = temporal.minus(days, DAYS);
837 }
838 return temporal;
839 }
840
841 /**
842 * Calculates the range of months based on the temporal.
843 *
844 * @param temporal the temporal, not null
845 * @return the month range, negative if not fixed range
846 */
847 private long monthRange(Temporal temporal) {
848 ValueRange startRange = Chronology.from(temporal).range(MONTH_OF_YEAR);
849 if (startRange.isFixed() && startRange.isIntValue()) {
850 return startRange.getMaximum() - startRange.getMinimum() + 1;
851 }
852 return -1;
853 }
854
855 //-----------------------------------------------------------------------
856 /**
857 * Checks if this period is equal to another period.
858 * <p>
859 * The comparison is based on the amounts held in the period.
860 * To be equal, the years, months and days units must be individually equal.
861 * Note that this means that a period of "15 Months" is not equal to a period
862 * of "1 Year and 3 Months".
863 *
864 * @param obj the object to check, null returns false
865 * @return true if this is equal to the other period
866 */
867 @Override
868 public boolean equals(Object obj) {
869 if (this == obj) {
870 return true;
871 }
872 if (obj instanceof Period) {
873 Period other = (Period) obj;
874 return years == other.years &&
875 months == other.months &&
876 days == other.days;
877 }
878 return false;
879 }
880
881 /**
882 * A hash code for this period.
883 *
884 * @return a suitable hash code
885 */
886 @Override
887 public int hashCode() {
888 return years + Integer.rotateLeft(months, 8) + Integer.rotateLeft(days, 16);
889 }
890
891 //-----------------------------------------------------------------------
892 /**
893 * Outputs this period as a {@code String}, such as {@code P6Y3M1D}.
894 * <p>
895 * The output will be in the ISO-8601 period format.
896 * A zero period will be represented as zero days, 'P0D'.
897 *
898 * @return a string representation of this period, not null
899 */
900 @Override
901 public String toString() {
902 if (this == ZERO) {
903 return "P0D";
904 } else {
905 StringBuilder buf = new StringBuilder();
906 buf.append('P');
907 if (years != 0) {
908 buf.append(years).append('Y');
909 }
910 if (months != 0) {
911 buf.append(months).append('M');
912 }
913 if (days != 0) {
914 buf.append(days).append('D');
915 }
916 return buf.toString();
917 }
918 }
919
920 //-----------------------------------------------------------------------
921 /**
922 * Writes the object using a
923 * <a href="../../serialized-form.html#java.time.Ser">dedicated serialized form</a>.
924 * <pre>
925 * out.writeByte(14); // identifies this as a Period
926 * out.writeInt(years);
927 * out.writeInt(months);
928 * out.writeInt(seconds);
929 * </pre>
930 *
931 * @return the instance of {@code Ser}, not null
932 */
933 private Object writeReplace() {
934 return new Ser(Ser.PERIOD_TYPE, this);
935 }
936
937 /**
938 * Defend against malicious streams.
939 * @return never
940 * @throws java.io.InvalidObjectException always
941 */
942 private Object readResolve() throws ObjectStreamException {
943 throw new InvalidObjectException("Deserialization via serialization delegate");
944 }
945
946 void writeExternal(DataOutput out) throws IOException {
947 out.writeInt(years);
948 out.writeInt(months);
949 out.writeInt(days);
950 }
951
952 static Period readExternal(DataInput in) throws IOException {
953 int years = in.readInt();
954 int months = in.readInt();
955 int days = in.readInt();
956 return Period.of(years, months, days);
957 }
958
959 }