1 /*
2 * Copyright (c) 2012, 2023, 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 *
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20 *
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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) 2007-2012, 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.DAY_OF_MONTH;
65 import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
66
67 import java.io.DataInput;
68 import java.io.DataOutput;
69 import java.io.IOException;
70 import java.io.InvalidObjectException;
71 import java.io.ObjectInputStream;
72 import java.io.Serializable;
73 import java.time.chrono.Chronology;
74 import java.time.chrono.IsoChronology;
75 import java.time.format.DateTimeFormatter;
76 import java.time.format.DateTimeFormatterBuilder;
77 import java.time.format.DateTimeParseException;
78 import java.time.temporal.ChronoField;
79 import java.time.temporal.Temporal;
80 import java.time.temporal.TemporalAccessor;
81 import java.time.temporal.TemporalAdjuster;
82 import java.time.temporal.TemporalField;
83 import java.time.temporal.TemporalQueries;
84 import java.time.temporal.TemporalQuery;
85 import java.time.temporal.UnsupportedTemporalTypeException;
86 import java.time.temporal.ValueRange;
87 import java.util.Objects;
88
89 /**
90 * A month-day in the ISO-8601 calendar system, such as {@code --12-03}.
91 * <p>
92 * {@code MonthDay} is an immutable date-time object that represents the combination
93 * of a month and day-of-month. Any field that can be derived from a month and day,
94 * such as quarter-of-year, can be obtained.
95 * <p>
96 * This class does not store or represent a year, time or time-zone.
97 * For example, the value "December 3rd" can be stored in a {@code MonthDay}.
98 * <p>
99 * Since a {@code MonthDay} does not possess a year, the leap day of
100 * February 29th is considered valid.
101 * <p>
102 * This class implements {@link TemporalAccessor} rather than {@link Temporal}.
103 * This is because it is not possible to define whether February 29th is valid or not
104 * without external information, preventing the implementation of plus/minus.
105 * Related to this, {@code MonthDay} only provides access to query and set the fields
106 * {@code MONTH_OF_YEAR} and {@code DAY_OF_MONTH}.
107 * <p>
108 * The ISO-8601 calendar system is the modern civil calendar system used today
109 * in most of the world. It is equivalent to the proleptic Gregorian calendar
110 * system, in which today's rules for leap years are applied for all time.
111 * For most applications written today, the ISO-8601 rules are entirely suitable.
112 * However, any application that makes use of historical dates, and requires them
113 * to be accurate will find the ISO-8601 approach unsuitable.
114 * <p>
115 * This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
116 * class; programmers should treat instances that are
117 * {@linkplain #equals(Object) equal} as interchangeable and should not
118 * use instances for synchronization, or unpredictable behavior may
119 * occur. For example, in a future release, synchronization may fail.
120 * The {@code equals} method should be used for comparisons.
121 *
122 * @implSpec
123 * This class is immutable and thread-safe.
124 *
125 * @since 1.8
126 */
127 @jdk.internal.ValueBased
128 public final class MonthDay
129 implements TemporalAccessor, TemporalAdjuster, Comparable<MonthDay>, Serializable {
130
131 /**
132 * Serialization version.
133 */
134 @java.io.Serial
135 private static final long serialVersionUID = -939150713474957432L;
136 /**
137 * Parser.
138 */
139 private static final DateTimeFormatter PARSER = new DateTimeFormatterBuilder()
140 .appendLiteral("--")
141 .appendValue(MONTH_OF_YEAR, 2)
142 .appendLiteral('-')
143 .appendValue(DAY_OF_MONTH, 2)
144 .toFormatter();
145
146 /**
147 * The month-of-year, not null.
148 */
149 private final int month;
150 /**
151 * The day-of-month.
152 */
153 private final int day;
154
155 //-----------------------------------------------------------------------
156 /**
157 * Obtains the current month-day from the system clock in the default time-zone.
158 * <p>
159 * This will query the {@link Clock#systemDefaultZone() system clock} in the default
160 * time-zone to obtain the current month-day.
161 * <p>
162 * Using this method will prevent the ability to use an alternate clock for testing
163 * because the clock is hard-coded.
164 *
165 * @return the current month-day using the system clock and default time-zone, not null
166 */
167 public static MonthDay now() {
168 return now(Clock.systemDefaultZone());
169 }
170
171 /**
172 * Obtains the current month-day from the system clock in the specified time-zone.
173 * <p>
174 * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current month-day.
175 * Specifying the time-zone avoids dependence on the default time-zone.
176 * <p>
177 * Using this method will prevent the ability to use an alternate clock for testing
178 * because the clock is hard-coded.
179 *
180 * @param zone the zone ID to use, not null
181 * @return the current month-day using the system clock, not null
182 */
183 public static MonthDay now(ZoneId zone) {
184 return now(Clock.system(zone));
185 }
186
187 /**
188 * Obtains the current month-day from the specified clock.
189 * <p>
190 * This will query the specified clock to obtain the current month-day.
191 * Using this method allows the use of an alternate clock for testing.
192 * The alternate clock may be introduced using {@link Clock dependency injection}.
193 *
194 * @param clock the clock to use, not null
195 * @return the current month-day, not null
196 */
197 public static MonthDay now(Clock clock) {
198 final LocalDate now = LocalDate.now(clock); // called once
199 return MonthDay.of(now.getMonth(), now.getDayOfMonth());
200 }
201
202 //-----------------------------------------------------------------------
203 /**
204 * Obtains an instance of {@code MonthDay}.
205 * <p>
206 * The day-of-month must be valid for the month within a leap year.
207 * Hence, for February, day 29 is valid.
208 * <p>
209 * For example, passing in April and day 31 will throw an exception, as
210 * there can never be April 31st in any year. By contrast, passing in
211 * February 29th is permitted, as that month-day can sometimes be valid.
212 *
213 * @param month the month-of-year to represent, not null
214 * @param dayOfMonth the day-of-month to represent, from 1 to 31
215 * @return the month-day, not null
216 * @throws DateTimeException if the value of any field is out of range,
217 * or if the day-of-month is invalid for the month
218 */
219 public static MonthDay of(Month month, int dayOfMonth) {
220 Objects.requireNonNull(month, "month");
221 DAY_OF_MONTH.checkValidValue(dayOfMonth);
222 if (dayOfMonth > month.maxLength()) {
223 throw new DateTimeException("Illegal value for DayOfMonth field, value " + dayOfMonth +
224 " is not valid for month " + month.name());
225 }
226 return new MonthDay(month.getValue(), dayOfMonth);
227 }
228
229 /**
230 * Obtains an instance of {@code MonthDay}.
231 * <p>
232 * The day-of-month must be valid for the month within a leap year.
233 * Hence, for month 2 (February), day 29 is valid.
234 * <p>
235 * For example, passing in month 4 (April) and day 31 will throw an exception, as
236 * there can never be April 31st in any year. By contrast, passing in
237 * February 29th is permitted, as that month-day can sometimes be valid.
238 *
239 * @param month the month-of-year to represent, from 1 (January) to 12 (December)
240 * @param dayOfMonth the day-of-month to represent, from 1 to 31
241 * @return the month-day, not null
242 * @throws DateTimeException if the value of any field is out of range,
243 * or if the day-of-month is invalid for the month
244 */
245 public static MonthDay of(int month, int dayOfMonth) {
246 return of(Month.of(month), dayOfMonth);
247 }
248
249 //-----------------------------------------------------------------------
250 /**
251 * Obtains an instance of {@code MonthDay} from a temporal object.
252 * <p>
253 * This obtains a month-day based on the specified temporal.
254 * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
255 * which this factory converts to an instance of {@code MonthDay}.
256 * <p>
257 * The conversion extracts the {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} and
258 * {@link ChronoField#DAY_OF_MONTH DAY_OF_MONTH} fields.
259 * The extraction is only permitted if the temporal object has an ISO
260 * chronology, or can be converted to a {@code LocalDate}.
261 * <p>
262 * This method matches the signature of the functional interface {@link TemporalQuery}
263 * allowing it to be used as a query via method reference, {@code MonthDay::from}.
264 *
265 * @param temporal the temporal object to convert, not null
266 * @return the month-day, not null
267 * @throws DateTimeException if unable to convert to a {@code MonthDay}
268 */
269 public static MonthDay from(TemporalAccessor temporal) {
270 if (temporal instanceof MonthDay) {
271 return (MonthDay) temporal;
272 }
273 try {
274 if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) {
275 temporal = LocalDate.from(temporal);
276 }
277 return of(temporal.get(MONTH_OF_YEAR), temporal.get(DAY_OF_MONTH));
278 } catch (DateTimeException ex) {
279 throw new DateTimeException("Unable to obtain MonthDay from TemporalAccessor: " +
280 temporal + " of type " + temporal.getClass().getName(), ex);
281 }
282 }
283
284 //-----------------------------------------------------------------------
285 /**
286 * Obtains an instance of {@code MonthDay} from a text string such as {@code --12-03}.
287 * <p>
288 * The string must represent a valid month-day.
289 * The format is {@code --MM-dd}.
290 *
291 * @param text the text to parse such as "--12-03", not null
292 * @return the parsed month-day, not null
293 * @throws DateTimeParseException if the text cannot be parsed
294 */
295 public static MonthDay parse(CharSequence text) {
296 return parse(text, PARSER);
297 }
298
299 /**
300 * Obtains an instance of {@code MonthDay} from a text string using a specific formatter.
301 * <p>
302 * The text is parsed using the formatter, returning a month-day.
303 *
304 * @param text the text to parse, not null
305 * @param formatter the formatter to use, not null
306 * @return the parsed month-day, not null
307 * @throws DateTimeParseException if the text cannot be parsed
308 */
309 public static MonthDay parse(CharSequence text, DateTimeFormatter formatter) {
310 Objects.requireNonNull(formatter, "formatter");
311 return formatter.parse(text, MonthDay::from);
312 }
313
314 //-----------------------------------------------------------------------
315 /**
316 * Constructor, previously validated.
317 *
318 * @param month the month-of-year to represent, validated from 1 to 12
319 * @param dayOfMonth the day-of-month to represent, validated from 1 to 29-31
320 */
321 private MonthDay(int month, int dayOfMonth) {
322 this.month = month;
323 this.day = dayOfMonth;
324 }
325
326 //-----------------------------------------------------------------------
327 /**
328 * Checks if the specified field is supported.
329 * <p>
330 * This checks if this month-day can be queried for the specified field.
331 * If false, then calling the {@link #range(TemporalField) range} and
332 * {@link #get(TemporalField) get} methods will throw an exception.
333 * <p>
334 * If the field is a {@link ChronoField} then the query is implemented here.
335 * The supported fields are:
336 * <ul>
337 * <li>{@code MONTH_OF_YEAR}
338 * <li>{@code YEAR}
339 * </ul>
340 * All other {@code ChronoField} instances will return false.
341 * <p>
342 * If the field is not a {@code ChronoField}, then the result of this method
343 * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
344 * passing {@code this} as the argument.
345 * Whether the field is supported is determined by the field.
346 *
347 * @param field the field to check, null returns false
348 * @return true if the field is supported on this month-day, false if not
349 */
350 @Override
351 public boolean isSupported(TemporalField field) {
352 if (field instanceof ChronoField) {
353 return field == MONTH_OF_YEAR || field == DAY_OF_MONTH;
354 }
355 return field != null && field.isSupportedBy(this);
356 }
357
358 /**
359 * Gets the range of valid values for the specified field.
360 * <p>
361 * The range object expresses the minimum and maximum valid values for a field.
362 * This month-day is used to enhance the accuracy of the returned range.
363 * If it is not possible to return the range, because the field is not supported
364 * or for some other reason, an exception is thrown.
365 * <p>
366 * If the field is a {@link ChronoField} then the query is implemented here.
367 * The {@link #isSupported(TemporalField) supported fields} will return
368 * appropriate range instances.
369 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
370 * <p>
371 * If the field is not a {@code ChronoField}, then the result of this method
372 * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
373 * passing {@code this} as the argument.
374 * Whether the range can be obtained is determined by the field.
375 *
376 * @param field the field to query the range for, not null
377 * @return the range of valid values for the field, not null
378 * @throws DateTimeException if the range for the field cannot be obtained
379 * @throws UnsupportedTemporalTypeException if the field is not supported
380 */
381 @Override
382 public ValueRange range(TemporalField field) {
383 if (field == MONTH_OF_YEAR) {
384 return field.range();
385 } else if (field == DAY_OF_MONTH) {
386 return ValueRange.of(1, getMonth().minLength(), getMonth().maxLength());
387 }
388 return TemporalAccessor.super.range(field);
389 }
390
391 /**
392 * Gets the value of the specified field from this month-day as an {@code int}.
393 * <p>
394 * This queries this month-day for the value of the specified field.
395 * The returned value will always be within the valid range of values for the field.
396 * If it is not possible to return the value, because the field is not supported
397 * or for some other reason, an exception is thrown.
398 * <p>
399 * If the field is a {@link ChronoField} then the query is implemented here.
400 * The {@link #isSupported(TemporalField) supported fields} will return valid
401 * values based on this month-day.
402 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
403 * <p>
404 * If the field is not a {@code ChronoField}, then the result of this method
405 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
406 * passing {@code this} as the argument. Whether the value can be obtained,
407 * and what the value represents, is determined by the field.
408 *
409 * @param field the field to get, not null
410 * @return the value for the field
411 * @throws DateTimeException if a value for the field cannot be obtained or
412 * the value is outside the range of valid values for the field
413 * @throws UnsupportedTemporalTypeException if the field is not supported or
414 * the range of values exceeds an {@code int}
415 * @throws ArithmeticException if numeric overflow occurs
416 */
417 @Override // override for Javadoc
418 public int get(TemporalField field) {
419 return range(field).checkValidIntValue(getLong(field), field);
420 }
421
422 /**
423 * Gets the value of the specified field from this month-day as a {@code long}.
424 * <p>
425 * This queries this month-day for the value of the specified field.
426 * If it is not possible to return the value, because the field is not supported
427 * or for some other reason, an exception is thrown.
428 * <p>
429 * If the field is a {@link ChronoField} then the query is implemented here.
430 * The {@link #isSupported(TemporalField) supported fields} will return valid
431 * values based on this month-day.
432 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
433 * <p>
434 * If the field is not a {@code ChronoField}, then the result of this method
435 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
436 * passing {@code this} as the argument. Whether the value can be obtained,
437 * and what the value represents, is determined by the field.
438 *
439 * @param field the field to get, not null
440 * @return the value for the field
441 * @throws DateTimeException if a value for the field cannot be obtained
442 * @throws UnsupportedTemporalTypeException if the field is not supported
443 * @throws ArithmeticException if numeric overflow occurs
444 */
445 @Override
446 public long getLong(TemporalField field) {
447 if (field instanceof ChronoField chronoField) {
448 return switch (chronoField) {
449 // alignedDOW and alignedWOM not supported because they cannot be set in with()
450 case DAY_OF_MONTH -> day;
451 case MONTH_OF_YEAR -> month;
452 default -> throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
453 };
454 }
455 return field.getFrom(this);
456 }
457
458 //-----------------------------------------------------------------------
459 /**
460 * Gets the month-of-year field from 1 to 12.
461 * <p>
462 * This method returns the month as an {@code int} from 1 to 12.
463 * Application code is frequently clearer if the enum {@link Month}
464 * is used by calling {@link #getMonth()}.
465 *
466 * @return the month-of-year, from 1 to 12
467 * @see #getMonth()
468 */
469 public int getMonthValue() {
470 return month;
471 }
472
473 /**
474 * Gets the month-of-year field using the {@code Month} enum.
475 * <p>
476 * This method returns the enum {@link Month} for the month.
477 * This avoids confusion as to what {@code int} values mean.
478 * If you need access to the primitive {@code int} value then the enum
479 * provides the {@link Month#getValue() int value}.
480 *
481 * @return the month-of-year, not null
482 * @see #getMonthValue()
483 */
484 public Month getMonth() {
485 return Month.of(month);
486 }
487
488 /**
489 * Gets the day-of-month field.
490 * <p>
491 * This method returns the primitive {@code int} value for the day-of-month.
492 *
493 * @return the day-of-month, from 1 to 31
494 */
495 public int getDayOfMonth() {
496 return day;
497 }
498
499 //-----------------------------------------------------------------------
500 /**
501 * Checks if the year is valid for this month-day.
502 * <p>
503 * This method checks whether this month and day and the input year form
504 * a valid date. This can only return false for February 29th.
505 *
506 * @param year the year to validate
507 * @return true if the year is valid for this month-day
508 * @see Year#isValidMonthDay(MonthDay)
509 */
510 public boolean isValidYear(int year) {
511 return (day == 29 && month == 2 && Year.isLeap(year) == false) == false;
512 }
513
514 //-----------------------------------------------------------------------
515 /**
516 * Returns a copy of this {@code MonthDay} with the month-of-year altered.
517 * <p>
518 * This returns a month-day with the specified month.
519 * If the day-of-month is invalid for the specified month, the day will
520 * be adjusted to the last valid day-of-month.
521 * <p>
522 * This instance is immutable and unaffected by this method call.
523 *
524 * @param month the month-of-year to set in the returned month-day, from 1 (January) to 12 (December)
525 * @return a {@code MonthDay} based on this month-day with the requested month, not null
526 * @throws DateTimeException if the month-of-year value is invalid
527 */
528 public MonthDay withMonth(int month) {
529 return with(Month.of(month));
530 }
531
532 /**
533 * Returns a copy of this {@code MonthDay} with the month-of-year altered.
534 * <p>
535 * This returns a month-day with the specified month.
536 * If the day-of-month is invalid for the specified month, the day will
537 * be adjusted to the last valid day-of-month.
538 * <p>
539 * This instance is immutable and unaffected by this method call.
540 *
541 * @param month the month-of-year to set in the returned month-day, not null
542 * @return a {@code MonthDay} based on this month-day with the requested month, not null
543 */
544 public MonthDay with(Month month) {
545 Objects.requireNonNull(month, "month");
546 if (month.getValue() == this.month) {
547 return this;
548 }
549 int day = Math.min(this.day, month.maxLength());
550 return new MonthDay(month.getValue(), day);
551 }
552
553 /**
554 * Returns a copy of this {@code MonthDay} with the day-of-month altered.
555 * <p>
556 * This returns a month-day with the specified day-of-month.
557 * If the day-of-month is invalid for the month, an exception is thrown.
558 * <p>
559 * This instance is immutable and unaffected by this method call.
560 *
561 * @param dayOfMonth the day-of-month to set in the return month-day, from 1 to 31
562 * @return a {@code MonthDay} based on this month-day with the requested day, not null
563 * @throws DateTimeException if the day-of-month value is invalid,
564 * or if the day-of-month is invalid for the month
565 */
566 public MonthDay withDayOfMonth(int dayOfMonth) {
567 if (dayOfMonth == this.day) {
568 return this;
569 }
570 return of(month, dayOfMonth);
571 }
572
573 //-----------------------------------------------------------------------
574 /**
575 * Queries this month-day using the specified query.
576 * <p>
577 * This queries this month-day using the specified query strategy object.
578 * The {@code TemporalQuery} object defines the logic to be used to
579 * obtain the result. Read the documentation of the query to understand
580 * what the result of this method will be.
581 * <p>
582 * The result of this method is obtained by invoking the
583 * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
584 * specified query passing {@code this} as the argument.
585 *
586 * @param <R> the type of the result
587 * @param query the query to invoke, not null
588 * @return the query result, null may be returned (defined by the query)
589 * @throws DateTimeException if unable to query (defined by the query)
590 * @throws ArithmeticException if numeric overflow occurs (defined by the query)
591 */
592 @SuppressWarnings("unchecked")
593 @Override
594 public <R> R query(TemporalQuery<R> query) {
595 if (query == TemporalQueries.chronology()) {
596 return (R) IsoChronology.INSTANCE;
597 }
598 return TemporalAccessor.super.query(query);
599 }
600
601 /**
602 * Adjusts the specified temporal object to have this month-day.
603 * <p>
604 * This returns a temporal object of the same observable type as the input
605 * with the month and day-of-month changed to be the same as this.
606 * <p>
607 * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
608 * twice, passing {@link ChronoField#MONTH_OF_YEAR} and
609 * {@link ChronoField#DAY_OF_MONTH} as the fields.
610 * If the specified temporal object does not use the ISO calendar system then
611 * a {@code DateTimeException} is thrown.
612 * <p>
613 * In most cases, it is clearer to reverse the calling pattern by using
614 * {@link Temporal#with(TemporalAdjuster)}:
615 * <pre>
616 * // these two lines are equivalent, but the second approach is recommended
617 * temporal = thisMonthDay.adjustInto(temporal);
618 * temporal = temporal.with(thisMonthDay);
619 * </pre>
620 * <p>
621 * This instance is immutable and unaffected by this method call.
622 *
623 * @param temporal the target object to be adjusted, not null
624 * @return the adjusted object, not null
625 * @throws DateTimeException if unable to make the adjustment
626 * @throws ArithmeticException if numeric overflow occurs
627 */
628 @Override
629 public Temporal adjustInto(Temporal temporal) {
630 if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) {
631 throw new DateTimeException("Adjustment only supported on ISO date-time");
632 }
633 temporal = temporal.with(MONTH_OF_YEAR, month);
634 return temporal.with(DAY_OF_MONTH, Math.min(temporal.range(DAY_OF_MONTH).getMaximum(), day));
635 }
636
637 /**
638 * Formats this month-day using the specified formatter.
639 * <p>
640 * This month-day will be passed to the formatter to produce a string.
641 *
642 * @param formatter the formatter to use, not null
643 * @return the formatted month-day string, not null
644 * @throws DateTimeException if an error occurs during printing
645 */
646 public String format(DateTimeFormatter formatter) {
647 Objects.requireNonNull(formatter, "formatter");
648 return formatter.format(this);
649 }
650
651 //-----------------------------------------------------------------------
652 /**
653 * Combines this month-day with a year to create a {@code LocalDate}.
654 * <p>
655 * This returns a {@code LocalDate} formed from this month-day and the specified year.
656 * <p>
657 * A month-day of February 29th will be adjusted to February 28th in the resulting
658 * date if the year is not a leap year.
659 * <p>
660 * This instance is immutable and unaffected by this method call.
661 *
662 * @param year the year to use, from MIN_YEAR to MAX_YEAR
663 * @return the local date formed from this month-day and the specified year, not null
664 * @throws DateTimeException if the year is outside the valid range of years
665 */
666 public LocalDate atYear(int year) {
667 return LocalDate.of(year, month, isValidYear(year) ? day : 28);
668 }
669
670 //-----------------------------------------------------------------------
671 /**
672 * Compares this month-day to another month-day.
673 * <p>
674 * The comparison is based first on value of the month, then on the value of the day.
675 * It is "consistent with equals", as defined by {@link Comparable}.
676 *
677 * @param other the other month-day to compare to, not null
678 * @return the comparator value, that is less than zero if this is before {@code other},
679 * zero if they are equal, greater than zero if this is after {@code other}
680 * @see #isBefore
681 * @see #isAfter
682 */
683 @Override
684 public int compareTo(MonthDay other) {
685 int cmp = (month - other.month);
686 if (cmp == 0) {
687 cmp = (day - other.day);
688 }
689 return cmp;
690 }
691
692 /**
693 * Checks if this month-day is after the specified month-day.
694 *
695 * @param other the other month-day to compare to, not null
696 * @return true if this is after the specified month-day
697 */
698 public boolean isAfter(MonthDay other) {
699 return compareTo(other) > 0;
700 }
701
702 /**
703 * Checks if this month-day is before the specified month-day.
704 *
705 * @param other the other month-day to compare to, not null
706 * @return true if this point is before the specified month-day
707 */
708 public boolean isBefore(MonthDay other) {
709 return compareTo(other) < 0;
710 }
711
712 //-----------------------------------------------------------------------
713 /**
714 * Checks if this month-day is equal to another month-day.
715 * <p>
716 * The comparison is based on the time-line position of the month-day within a year.
717 *
718 * @param obj the object to check, null returns false
719 * @return true if this is equal to the other month-day
720 */
721 @Override
722 public boolean equals(Object obj) {
723 if (this == obj) {
724 return true;
725 }
726 return (obj instanceof MonthDay other)
727 && month == other.month
728 && day == other.day;
729 }
730
731 /**
732 * A hash code for this month-day.
733 *
734 * @return a suitable hash code
735 */
736 @Override
737 public int hashCode() {
738 return (month << 6) + day;
739 }
740
741 //-----------------------------------------------------------------------
742 /**
743 * Outputs this month-day as a {@code String}, such as {@code --12-03}.
744 * <p>
745 * The output will be in the format {@code --MM-dd}:
746 *
747 * @return a string representation of this month-day, not null
748 */
749 @Override
750 public String toString() {
751 return new StringBuilder(10).append("--")
752 .append(month < 10 ? "0" : "").append(month)
753 .append(day < 10 ? "-0" : "-").append(day)
754 .toString();
755 }
756
757 //-----------------------------------------------------------------------
758 /**
759 * Writes the object using a
760 * <a href="{@docRoot}/serialized-form.html#java.time.Ser">dedicated serialized form</a>.
761 * @serialData
762 * <pre>
763 * out.writeByte(13); // identifies a MonthDay
764 * out.writeByte(month);
765 * out.writeByte(day);
766 * </pre>
767 *
768 * @return the instance of {@code Ser}, not null
769 */
770 @java.io.Serial
771 private Object writeReplace() {
772 return new Ser(Ser.MONTH_DAY_TYPE, this);
773 }
774
775 /**
776 * Defend against malicious streams.
777 *
778 * @param s the stream to read
779 * @throws InvalidObjectException always
780 */
781 @java.io.Serial
782 private void readObject(ObjectInputStream s) throws InvalidObjectException {
783 throw new InvalidObjectException("Deserialization via serialization delegate");
784 }
785
786 void writeExternal(DataOutput out) throws IOException {
787 out.writeByte(month);
788 out.writeByte(day);
789 }
790
791 static MonthDay readExternal(DataInput in) throws IOException {
792 byte month = in.readByte();
793 byte day = in.readByte();
794 return MonthDay.of(month, day);
795 }
796
797 }