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 *
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
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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 @jdk.internal.MigratedValueClass
129 public final class MonthDay
130 implements TemporalAccessor, TemporalAdjuster, Comparable<MonthDay>, Serializable {
131
132 /**
133 * Serialization version.
134 */
135 @java.io.Serial
136 private static final long serialVersionUID = -939150713474957432L;
137 /**
138 * Parser.
139 */
140 private static final DateTimeFormatter PARSER = new DateTimeFormatterBuilder()
141 .appendLiteral("--")
142 .appendValue(MONTH_OF_YEAR, 2)
143 .appendLiteral('-')
144 .appendValue(DAY_OF_MONTH, 2)
145 .toFormatter();
146
147 /**
148 * The month-of-year, not null.
149 */
150 private final int month;
151 /**
152 * The day-of-month.
153 */
154 private final int day;
155
156 //-----------------------------------------------------------------------
157 /**
158 * Obtains the current month-day from the system clock in the default time-zone.
159 * <p>
160 * This will query the {@link Clock#systemDefaultZone() system clock} in the default
161 * time-zone to obtain the current month-day.
162 * <p>
163 * Using this method will prevent the ability to use an alternate clock for testing
164 * because the clock is hard-coded.
165 *
166 * @return the current month-day using the system clock and default time-zone, not null
167 */
168 public static MonthDay now() {
169 return now(Clock.systemDefaultZone());
170 }
171
172 /**
173 * Obtains the current month-day from the system clock in the specified time-zone.
174 * <p>
175 * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current month-day.
176 * Specifying the time-zone avoids dependence on the default time-zone.
177 * <p>
178 * Using this method will prevent the ability to use an alternate clock for testing
179 * because the clock is hard-coded.
180 *
181 * @param zone the zone ID to use, not null
182 * @return the current month-day using the system clock, not null
183 */
184 public static MonthDay now(ZoneId zone) {
185 return now(Clock.system(zone));
186 }
187
188 /**
189 * Obtains the current month-day from the specified clock.
190 * <p>
191 * This will query the specified clock to obtain the current month-day.
192 * Using this method allows the use of an alternate clock for testing.
193 * The alternate clock may be introduced using {@link Clock dependency injection}.
194 *
195 * @param clock the clock to use, not null
196 * @return the current month-day, not null
197 */
198 public static MonthDay now(Clock clock) {
199 final LocalDate now = LocalDate.now(clock); // called once
200 return MonthDay.of(now.getMonth(), now.getDayOfMonth());
201 }
202
203 //-----------------------------------------------------------------------
204 /**
205 * Obtains an instance of {@code MonthDay}.
206 * <p>
207 * The day-of-month must be valid for the month within a leap year.
208 * Hence, for February, day 29 is valid.
209 * <p>
210 * For example, passing in April and day 31 will throw an exception, as
211 * there can never be April 31st in any year. By contrast, passing in
212 * February 29th is permitted, as that month-day can sometimes be valid.
213 *
214 * @param month the month-of-year to represent, not null
215 * @param dayOfMonth the day-of-month to represent, from 1 to 31
216 * @return the month-day, not null
217 * @throws DateTimeException if the value of any field is out of range,
218 * or if the day-of-month is invalid for the month
219 */
220 public static MonthDay of(Month month, int dayOfMonth) {
221 Objects.requireNonNull(month, "month");
222 DAY_OF_MONTH.checkValidValue(dayOfMonth);
223 if (dayOfMonth > month.maxLength()) {
224 throw new DateTimeException("Illegal value for DayOfMonth field, value " + dayOfMonth +
225 " is not valid for month " + month.name());
226 }
227 return new MonthDay(month.getValue(), dayOfMonth);
228 }
229
230 /**
231 * Obtains an instance of {@code MonthDay}.
232 * <p>
233 * The day-of-month must be valid for the month within a leap year.
234 * Hence, for month 2 (February), day 29 is valid.
235 * <p>
236 * For example, passing in month 4 (April) and day 31 will throw an exception, as
237 * there can never be April 31st in any year. By contrast, passing in
238 * February 29th is permitted, as that month-day can sometimes be valid.
239 *
240 * @param month the month-of-year to represent, from 1 (January) to 12 (December)
241 * @param dayOfMonth the day-of-month to represent, from 1 to 31
242 * @return the month-day, not null
243 * @throws DateTimeException if the value of any field is out of range,
244 * or if the day-of-month is invalid for the month
245 */
246 public static MonthDay of(int month, int dayOfMonth) {
247 return of(Month.of(month), dayOfMonth);
248 }
249
250 //-----------------------------------------------------------------------
251 /**
252 * Obtains an instance of {@code MonthDay} from a temporal object.
253 * <p>
254 * This obtains a month-day based on the specified temporal.
255 * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
256 * which this factory converts to an instance of {@code MonthDay}.
257 * <p>
258 * The conversion extracts the {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} and
259 * {@link ChronoField#DAY_OF_MONTH DAY_OF_MONTH} fields.
260 * The extraction is only permitted if the temporal object has an ISO
261 * chronology, or can be converted to a {@code LocalDate}.
262 * <p>
263 * This method matches the signature of the functional interface {@link TemporalQuery}
264 * allowing it to be used as a query via method reference, {@code MonthDay::from}.
265 *
266 * @param temporal the temporal object to convert, not null
267 * @return the month-day, not null
268 * @throws DateTimeException if unable to convert to a {@code MonthDay}
269 */
270 public static MonthDay from(TemporalAccessor temporal) {
271 if (temporal instanceof MonthDay) {
272 return (MonthDay) temporal;
273 }
274 try {
275 if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) {
276 temporal = LocalDate.from(temporal);
277 }
278 return of(temporal.get(MONTH_OF_YEAR), temporal.get(DAY_OF_MONTH));
279 } catch (DateTimeException ex) {
280 throw new DateTimeException("Unable to obtain MonthDay from TemporalAccessor: " +
281 temporal + " of type " + temporal.getClass().getName(), ex);
282 }
283 }
284
285 //-----------------------------------------------------------------------
286 /**
287 * Obtains an instance of {@code MonthDay} from a text string such as {@code --12-03}.
288 * <p>
289 * The string must represent a valid month-day.
290 * The format is {@code --MM-dd}.
291 *
292 * @param text the text to parse such as "--12-03", not null
293 * @return the parsed month-day, not null
294 * @throws DateTimeParseException if the text cannot be parsed
295 */
296 public static MonthDay parse(CharSequence text) {
297 return parse(text, PARSER);
298 }
299
300 /**
301 * Obtains an instance of {@code MonthDay} from a text string using a specific formatter.
302 * <p>
303 * The text is parsed using the formatter, returning a month-day.
304 *
305 * @param text the text to parse, not null
306 * @param formatter the formatter to use, not null
307 * @return the parsed month-day, not null
308 * @throws DateTimeParseException if the text cannot be parsed
309 */
310 public static MonthDay parse(CharSequence text, DateTimeFormatter formatter) {
311 Objects.requireNonNull(formatter, "formatter");
312 return formatter.parse(text, MonthDay::from);
313 }
314
315 //-----------------------------------------------------------------------
316 /**
317 * Constructor, previously validated.
318 *
319 * @param month the month-of-year to represent, validated from 1 to 12
320 * @param dayOfMonth the day-of-month to represent, validated from 1 to 29-31
321 */
322 private MonthDay(int month, int dayOfMonth) {
323 this.month = month;
324 this.day = dayOfMonth;
325 }
326
327 //-----------------------------------------------------------------------
328 /**
329 * Checks if the specified field is supported.
330 * <p>
331 * This checks if this month-day can be queried for the specified field.
332 * If false, then calling the {@link #range(TemporalField) range} and
333 * {@link #get(TemporalField) get} methods will throw an exception.
334 * <p>
335 * If the field is a {@link ChronoField} then the query is implemented here.
336 * The supported fields are:
337 * <ul>
338 * <li>{@code MONTH_OF_YEAR}
339 * <li>{@code YEAR}
340 * </ul>
341 * All other {@code ChronoField} instances will return false.
342 * <p>
343 * If the field is not a {@code ChronoField}, then the result of this method
344 * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
345 * passing {@code this} as the argument.
346 * Whether the field is supported is determined by the field.
347 *
348 * @param field the field to check, null returns false
349 * @return true if the field is supported on this month-day, false if not
350 */
351 @Override
352 public boolean isSupported(TemporalField field) {
353 if (field instanceof ChronoField) {
354 return field == MONTH_OF_YEAR || field == DAY_OF_MONTH;
355 }
356 return field != null && field.isSupportedBy(this);
357 }
358
359 /**
360 * Gets the range of valid values for the specified field.
361 * <p>
362 * The range object expresses the minimum and maximum valid values for a field.
363 * This month-day is used to enhance the accuracy of the returned range.
364 * If it is not possible to return the range, because the field is not supported
365 * or for some other reason, an exception is thrown.
366 * <p>
367 * If the field is a {@link ChronoField} then the query is implemented here.
368 * The {@link #isSupported(TemporalField) supported fields} will return
369 * appropriate range instances.
370 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
371 * <p>
372 * If the field is not a {@code ChronoField}, then the result of this method
373 * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
374 * passing {@code this} as the argument.
375 * Whether the range can be obtained is determined by the field.
376 *
377 * @param field the field to query the range for, not null
378 * @return the range of valid values for the field, not null
379 * @throws DateTimeException if the range for the field cannot be obtained
380 * @throws UnsupportedTemporalTypeException if the field is not supported
381 */
382 @Override
383 public ValueRange range(TemporalField field) {
384 if (field == MONTH_OF_YEAR) {
385 return field.range();
386 } else if (field == DAY_OF_MONTH) {
387 return ValueRange.of(1, getMonth().minLength(), getMonth().maxLength());
388 }
389 return TemporalAccessor.super.range(field);
390 }
391
392 /**
393 * Gets the value of the specified field from this month-day as an {@code int}.
394 * <p>
395 * This queries this month-day for the value of the specified field.
396 * The returned value will always be within the valid range of values for the field.
397 * If it is not possible to return the value, because the field is not supported
398 * or for some other reason, an exception is thrown.
399 * <p>
400 * If the field is a {@link ChronoField} then the query is implemented here.
401 * The {@link #isSupported(TemporalField) supported fields} will return valid
402 * values based on this month-day.
403 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
404 * <p>
405 * If the field is not a {@code ChronoField}, then the result of this method
406 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
407 * passing {@code this} as the argument. Whether the value can be obtained,
408 * and what the value represents, is determined by the field.
409 *
410 * @param field the field to get, not null
411 * @return the value for the field
412 * @throws DateTimeException if a value for the field cannot be obtained or
413 * the value is outside the range of valid values for the field
414 * @throws UnsupportedTemporalTypeException if the field is not supported or
415 * the range of values exceeds an {@code int}
416 * @throws ArithmeticException if numeric overflow occurs
417 */
418 @Override // override for Javadoc
419 public int get(TemporalField field) {
420 return range(field).checkValidIntValue(getLong(field), field);
421 }
422
423 /**
424 * Gets the value of the specified field from this month-day as a {@code long}.
425 * <p>
426 * This queries this month-day for the value of the specified field.
427 * If it is not possible to return the value, because the field is not supported
428 * or for some other reason, an exception is thrown.
429 * <p>
430 * If the field is a {@link ChronoField} then the query is implemented here.
431 * The {@link #isSupported(TemporalField) supported fields} will return valid
432 * values based on this month-day.
433 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
434 * <p>
435 * If the field is not a {@code ChronoField}, then the result of this method
436 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
437 * passing {@code this} as the argument. Whether the value can be obtained,
438 * and what the value represents, is determined by the field.
439 *
440 * @param field the field to get, not null
441 * @return the value for the field
442 * @throws DateTimeException if a value for the field cannot be obtained
443 * @throws UnsupportedTemporalTypeException if the field is not supported
444 * @throws ArithmeticException if numeric overflow occurs
445 */
446 @Override
447 public long getLong(TemporalField field) {
448 if (field instanceof ChronoField chronoField) {
449 return switch (chronoField) {
450 // alignedDOW and alignedWOM not supported because they cannot be set in with()
451 case DAY_OF_MONTH -> day;
452 case MONTH_OF_YEAR -> month;
453 default -> throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
454 };
455 }
456 return field.getFrom(this);
457 }
458
459 //-----------------------------------------------------------------------
460 /**
461 * Gets the month-of-year field from 1 to 12.
462 * <p>
463 * This method returns the month as an {@code int} from 1 to 12.
464 * Application code is frequently clearer if the enum {@link Month}
465 * is used by calling {@link #getMonth()}.
466 *
467 * @return the month-of-year, from 1 to 12
468 * @see #getMonth()
469 */
470 public int getMonthValue() {
471 return month;
472 }
473
474 /**
475 * Gets the month-of-year field using the {@code Month} enum.
476 * <p>
477 * This method returns the enum {@link Month} for the month.
478 * This avoids confusion as to what {@code int} values mean.
479 * If you need access to the primitive {@code int} value then the enum
480 * provides the {@link Month#getValue() int value}.
481 *
482 * @return the month-of-year, not null
483 * @see #getMonthValue()
484 */
485 public Month getMonth() {
486 return Month.of(month);
487 }
488
489 /**
490 * Gets the day-of-month field.
491 * <p>
492 * This method returns the primitive {@code int} value for the day-of-month.
493 *
494 * @return the day-of-month, from 1 to 31
495 */
496 public int getDayOfMonth() {
497 return day;
498 }
499
500 //-----------------------------------------------------------------------
501 /**
502 * Checks if the year is valid for this month-day.
503 * <p>
504 * This method checks whether this month and day and the input year form
505 * a valid date. This can only return false for February 29th.
506 *
507 * @param year the year to validate
508 * @return true if the year is valid for this month-day
509 * @see Year#isValidMonthDay(MonthDay)
510 */
511 public boolean isValidYear(int year) {
512 return (day == 29 && month == 2 && Year.isLeap(year) == false) == false;
513 }
514
515 //-----------------------------------------------------------------------
516 /**
517 * Returns a copy of this {@code MonthDay} with the month-of-year altered.
518 * <p>
519 * This returns a month-day with the specified month.
520 * If the day-of-month is invalid for the specified month, the day will
521 * be adjusted to the last valid day-of-month.
522 * <p>
523 * This instance is immutable and unaffected by this method call.
524 *
525 * @param month the month-of-year to set in the returned month-day, from 1 (January) to 12 (December)
526 * @return a {@code MonthDay} based on this month-day with the requested month, not null
527 * @throws DateTimeException if the month-of-year value is invalid
528 */
529 public MonthDay withMonth(int month) {
530 return with(Month.of(month));
531 }
532
533 /**
534 * Returns a copy of this {@code MonthDay} with the month-of-year altered.
535 * <p>
536 * This returns a month-day with the specified month.
537 * If the day-of-month is invalid for the specified month, the day will
538 * be adjusted to the last valid day-of-month.
539 * <p>
540 * This instance is immutable and unaffected by this method call.
541 *
542 * @param month the month-of-year to set in the returned month-day, not null
543 * @return a {@code MonthDay} based on this month-day with the requested month, not null
544 */
545 public MonthDay with(Month month) {
546 Objects.requireNonNull(month, "month");
547 if (month.getValue() == this.month) {
548 return this;
549 }
550 int day = Math.min(this.day, month.maxLength());
551 return new MonthDay(month.getValue(), day);
552 }
553
554 /**
555 * Returns a copy of this {@code MonthDay} with the day-of-month altered.
556 * <p>
557 * This returns a month-day with the specified day-of-month.
558 * If the day-of-month is invalid for the month, an exception is thrown.
559 * <p>
560 * This instance is immutable and unaffected by this method call.
561 *
562 * @param dayOfMonth the day-of-month to set in the return month-day, from 1 to 31
563 * @return a {@code MonthDay} based on this month-day with the requested day, not null
564 * @throws DateTimeException if the day-of-month value is invalid,
565 * or if the day-of-month is invalid for the month
566 */
567 public MonthDay withDayOfMonth(int dayOfMonth) {
568 if (dayOfMonth == this.day) {
569 return this;
570 }
571 return of(month, dayOfMonth);
572 }
573
574 //-----------------------------------------------------------------------
575 /**
576 * Queries this month-day using the specified query.
577 * <p>
578 * This queries this month-day using the specified query strategy object.
579 * The {@code TemporalQuery} object defines the logic to be used to
580 * obtain the result. Read the documentation of the query to understand
581 * what the result of this method will be.
582 * <p>
583 * The result of this method is obtained by invoking the
584 * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
585 * specified query passing {@code this} as the argument.
586 *
587 * @param <R> the type of the result
588 * @param query the query to invoke, not null
589 * @return the query result, null may be returned (defined by the query)
590 * @throws DateTimeException if unable to query (defined by the query)
591 * @throws ArithmeticException if numeric overflow occurs (defined by the query)
592 */
593 @SuppressWarnings("unchecked")
594 @Override
595 public <R> R query(TemporalQuery<R> query) {
596 if (query == TemporalQueries.chronology()) {
597 return (R) IsoChronology.INSTANCE;
598 }
599 return TemporalAccessor.super.query(query);
600 }
601
602 /**
603 * Adjusts the specified temporal object to have this month-day.
604 * <p>
605 * This returns a temporal object of the same observable type as the input
606 * with the month and day-of-month changed to be the same as this.
607 * <p>
608 * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
609 * twice, passing {@link ChronoField#MONTH_OF_YEAR} and
610 * {@link ChronoField#DAY_OF_MONTH} as the fields.
611 * If the specified temporal object does not use the ISO calendar system then
612 * a {@code DateTimeException} is thrown.
613 * <p>
614 * In most cases, it is clearer to reverse the calling pattern by using
615 * {@link Temporal#with(TemporalAdjuster)}:
616 * <pre>
617 * // these two lines are equivalent, but the second approach is recommended
618 * temporal = thisMonthDay.adjustInto(temporal);
619 * temporal = temporal.with(thisMonthDay);
620 * </pre>
621 * <p>
622 * This instance is immutable and unaffected by this method call.
623 *
624 * @param temporal the target object to be adjusted, not null
625 * @return the adjusted object, not null
626 * @throws DateTimeException if unable to make the adjustment
627 * @throws ArithmeticException if numeric overflow occurs
628 */
629 @Override
630 public Temporal adjustInto(Temporal temporal) {
631 if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) {
632 throw new DateTimeException("Adjustment only supported on ISO date-time");
633 }
634 temporal = temporal.with(MONTH_OF_YEAR, month);
635 return temporal.with(DAY_OF_MONTH, Math.min(temporal.range(DAY_OF_MONTH).getMaximum(), day));
636 }
637
638 /**
639 * Formats this month-day using the specified formatter.
640 * <p>
641 * This month-day will be passed to the formatter to produce a string.
642 *
643 * @param formatter the formatter to use, not null
644 * @return the formatted month-day string, not null
645 * @throws DateTimeException if an error occurs during printing
646 */
647 public String format(DateTimeFormatter formatter) {
648 Objects.requireNonNull(formatter, "formatter");
649 return formatter.format(this);
650 }
651
652 //-----------------------------------------------------------------------
653 /**
654 * Combines this month-day with a year to create a {@code LocalDate}.
655 * <p>
656 * This returns a {@code LocalDate} formed from this month-day and the specified year.
657 * <p>
658 * A month-day of February 29th will be adjusted to February 28th in the resulting
659 * date if the year is not a leap year.
660 * <p>
661 * This instance is immutable and unaffected by this method call.
662 *
663 * @param year the year to use, from MIN_YEAR to MAX_YEAR
664 * @return the local date formed from this month-day and the specified year, not null
665 * @throws DateTimeException if the year is outside the valid range of years
666 */
667 public LocalDate atYear(int year) {
668 return LocalDate.of(year, month, isValidYear(year) ? day : 28);
669 }
670
671 //-----------------------------------------------------------------------
672 /**
673 * Compares this month-day to another month-day.
674 * <p>
675 * The comparison is based first on value of the month, then on the value of the day.
676 * It is "consistent with equals", as defined by {@link Comparable}.
677 *
678 * @param other the other month-day to compare to, not null
679 * @return the comparator value, that is less than zero if this is before {@code other},
680 * zero if they are equal, greater than zero if this is after {@code other}
681 * @see #isBefore
682 * @see #isAfter
683 */
684 @Override
685 public int compareTo(MonthDay other) {
686 int cmp = (month - other.month);
687 if (cmp == 0) {
688 cmp = (day - other.day);
689 }
690 return cmp;
691 }
692
693 /**
694 * Checks if this month-day is after the specified month-day.
695 *
696 * @param other the other month-day to compare to, not null
697 * @return true if this is after the specified month-day
698 */
699 public boolean isAfter(MonthDay other) {
700 return compareTo(other) > 0;
701 }
702
703 /**
704 * Checks if this month-day is before the specified month-day.
705 *
706 * @param other the other month-day to compare to, not null
707 * @return true if this point is before the specified month-day
708 */
709 public boolean isBefore(MonthDay other) {
710 return compareTo(other) < 0;
711 }
712
713 //-----------------------------------------------------------------------
714 /**
715 * Checks if this month-day is equal to another month-day.
716 * <p>
717 * The comparison is based on the time-line position of the month-day within a year.
718 *
719 * @param obj the object to check, null returns false
720 * @return true if this is equal to the other month-day
721 */
722 @Override
723 public boolean equals(Object obj) {
724 if (this == obj) {
725 return true;
726 }
727 return (obj instanceof MonthDay other)
728 && month == other.month
729 && day == other.day;
730 }
731
732 /**
733 * A hash code for this month-day.
734 *
735 * @return a suitable hash code
736 */
737 @Override
738 public int hashCode() {
739 return (month << 6) + day;
740 }
741
742 //-----------------------------------------------------------------------
743 /**
744 * Outputs this month-day as a {@code String}, such as {@code --12-03}.
745 * <p>
746 * The output will be in the format {@code --MM-dd}:
747 *
748 * @return a string representation of this month-day, not null
749 */
750 @Override
751 public String toString() {
752 return new StringBuilder(10).append("--")
753 .append(month < 10 ? "0" : "").append(month)
754 .append(day < 10 ? "-0" : "-").append(day)
755 .toString();
756 }
757
758 //-----------------------------------------------------------------------
759 /**
760 * Writes the object using a
761 * <a href="{@docRoot}/serialized-form.html#java.time.Ser">dedicated serialized form</a>.
762 * @serialData
763 * <pre>
764 * out.writeByte(13); // identifies a MonthDay
765 * out.writeByte(month);
766 * out.writeByte(day);
767 * </pre>
768 *
769 * @return the instance of {@code Ser}, not null
770 */
771 @java.io.Serial
772 private Object writeReplace() {
773 return new Ser(Ser.MONTH_DAY_TYPE, this);
774 }
775
776 /**
777 * Defend against malicious streams.
778 *
779 * @param s the stream to read
780 * @throws InvalidObjectException always
781 */
782 @java.io.Serial
783 private void readObject(ObjectInputStream s) throws InvalidObjectException {
784 throw new InvalidObjectException("Deserialization via serialization delegate");
785 }
786
787 void writeExternal(DataOutput out) throws IOException {
788 out.writeByte(month);
789 out.writeByte(day);
790 }
791
792 static MonthDay readExternal(DataInput in) throws IOException {
793 byte month = in.readByte();
794 byte day = in.readByte();
795 return MonthDay.of(month, day);
796 }
797
798 }