1 /*
2 * Copyright (c) 2012, 2015, 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
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7 * published by the Free Software Foundation. Oracle designates this
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10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
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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).
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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
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56 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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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.MONTHS;
66
67 import java.time.chrono.Chronology;
68 import java.time.chrono.IsoChronology;
69 import java.time.format.DateTimeFormatterBuilder;
70 import java.time.format.TextStyle;
71 import java.time.temporal.ChronoField;
72 import java.time.temporal.Temporal;
73 import java.time.temporal.TemporalAccessor;
74 import java.time.temporal.TemporalAdjuster;
75 import java.time.temporal.TemporalField;
76 import java.time.temporal.TemporalQueries;
77 import java.time.temporal.TemporalQuery;
78 import java.time.temporal.UnsupportedTemporalTypeException;
79 import java.time.temporal.ValueRange;
80 import java.util.Locale;
81
82 /**
83 * A month-of-year, such as 'July'.
84 * <p>
85 * {@code Month} is an enum representing the 12 months of the year -
86 * January, February, March, April, May, June, July, August, September, October,
87 * November and December.
88 * <p>
89 * In addition to the textual enum name, each month-of-year has an {@code int} value.
90 * The {@code int} value follows normal usage and the ISO-8601 standard,
91 * from 1 (January) to 12 (December). It is recommended that applications use the enum
92 * rather than the {@code int} value to ensure code clarity.
93 * <p>
94 * <b>Do not use {@code ordinal()} to obtain the numeric representation of {@code Month}.
95 * Use {@code getValue()} instead.</b>
96 * <p>
97 * This enum represents a common concept that is found in many calendar systems.
98 * As such, this enum may be used by any calendar system that has the month-of-year
99 * concept defined exactly equivalent to the ISO-8601 calendar system.
100 *
101 * @implSpec
102 * This is an immutable and thread-safe enum.
103 *
104 * @since 1.8
105 */
106 public enum Month implements TemporalAccessor, TemporalAdjuster {
107
108 /**
109 * The singleton instance for the month of January with 31 days.
110 * This has the numeric value of {@code 1}.
111 */
112 JANUARY,
113 /**
114 * The singleton instance for the month of February with 28 days, or 29 in a leap year.
115 * This has the numeric value of {@code 2}.
116 */
117 FEBRUARY,
118 /**
119 * The singleton instance for the month of March with 31 days.
120 * This has the numeric value of {@code 3}.
121 */
122 MARCH,
123 /**
124 * The singleton instance for the month of April with 30 days.
125 * This has the numeric value of {@code 4}.
126 */
127 APRIL,
128 /**
129 * The singleton instance for the month of May with 31 days.
130 * This has the numeric value of {@code 5}.
131 */
132 MAY,
133 /**
134 * The singleton instance for the month of June with 30 days.
135 * This has the numeric value of {@code 6}.
136 */
137 JUNE,
138 /**
139 * The singleton instance for the month of July with 31 days.
140 * This has the numeric value of {@code 7}.
141 */
142 JULY,
143 /**
144 * The singleton instance for the month of August with 31 days.
145 * This has the numeric value of {@code 8}.
146 */
147 AUGUST,
148 /**
149 * The singleton instance for the month of September with 30 days.
150 * This has the numeric value of {@code 9}.
151 */
152 SEPTEMBER,
153 /**
154 * The singleton instance for the month of October with 31 days.
155 * This has the numeric value of {@code 10}.
156 */
157 OCTOBER,
158 /**
159 * The singleton instance for the month of November with 30 days.
160 * This has the numeric value of {@code 11}.
161 */
162 NOVEMBER,
163 /**
164 * The singleton instance for the month of December with 31 days.
165 * This has the numeric value of {@code 12}.
166 */
167 DECEMBER;
168 /**
169 * Private cache of all the constants.
170 */
171 private static final Month[] ENUMS = Month.values();
172
173 //-----------------------------------------------------------------------
174 /**
175 * Obtains an instance of {@code Month} from an {@code int} value.
176 * <p>
177 * {@code Month} is an enum representing the 12 months of the year.
178 * This factory allows the enum to be obtained from the {@code int} value.
179 * The {@code int} value follows the ISO-8601 standard, from 1 (January) to 12 (December).
180 *
181 * @param month the month-of-year to represent, from 1 (January) to 12 (December)
182 * @return the month-of-year, not null
183 * @throws DateTimeException if the month-of-year is invalid
184 */
185 public static Month of(int month) {
186 if (month < 1 || month > 12) {
187 throw new DateTimeException("Invalid value for MonthOfYear: " + month);
188 }
189 return ENUMS[month - 1];
190 }
191
192 //-----------------------------------------------------------------------
193 /**
194 * Obtains an instance of {@code Month} from a temporal object.
195 * <p>
196 * This obtains a month based on the specified temporal.
197 * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
198 * which this factory converts to an instance of {@code Month}.
199 * <p>
200 * The conversion extracts the {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} field.
201 * The extraction is only permitted if the temporal object has an ISO
202 * chronology, or can be converted to a {@code LocalDate}.
203 * <p>
204 * This method matches the signature of the functional interface {@link TemporalQuery}
205 * allowing it to be used as a query via method reference, {@code Month::from}.
206 *
207 * @param temporal the temporal object to convert, not null
208 * @return the month-of-year, not null
209 * @throws DateTimeException if unable to convert to a {@code Month}
210 */
211 public static Month from(TemporalAccessor temporal) {
212 if (temporal instanceof Month) {
213 return (Month) temporal;
214 }
215 try {
216 if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) {
217 temporal = LocalDate.from(temporal);
218 }
219 return of(temporal.get(MONTH_OF_YEAR));
220 } catch (DateTimeException ex) {
221 throw new DateTimeException("Unable to obtain Month from TemporalAccessor: " +
222 temporal + " of type " + temporal.getClass().getName(), ex);
223 }
224 }
225
226 //-----------------------------------------------------------------------
227 /**
228 * Gets the month-of-year {@code int} value.
229 * <p>
230 * The values are numbered following the ISO-8601 standard,
231 * from 1 (January) to 12 (December).
232 *
233 * @return the month-of-year, from 1 (January) to 12 (December)
234 */
235 public int getValue() {
236 return ordinal() + 1;
237 }
238
239 //-----------------------------------------------------------------------
240 /**
241 * Gets the textual representation, such as 'Jan' or 'December'.
242 * <p>
243 * This returns the textual name used to identify the month-of-year,
244 * suitable for presentation to the user.
245 * The parameters control the style of the returned text and the locale.
246 * <p>
247 * If no textual mapping is found then the {@link #getValue() numeric value} is returned.
248 *
249 * @param style the length of the text required, not null
250 * @param locale the locale to use, not null
251 * @return the text value of the month-of-year, not null
252 */
253 public String getDisplayName(TextStyle style, Locale locale) {
254 return new DateTimeFormatterBuilder().appendText(MONTH_OF_YEAR, style).toFormatter(locale).format(this);
255 }
256
257 //-----------------------------------------------------------------------
258 /**
259 * Checks if the specified field is supported.
260 * <p>
261 * This checks if this month-of-year can be queried for the specified field.
262 * If false, then calling the {@link #range(TemporalField) range} and
263 * {@link #get(TemporalField) get} methods will throw an exception.
264 * <p>
265 * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then
266 * this method returns true.
267 * All other {@code ChronoField} instances will return false.
268 * <p>
269 * If the field is not a {@code ChronoField}, then the result of this method
270 * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
271 * passing {@code this} as the argument.
272 * Whether the field is supported is determined by the field.
273 *
274 * @param field the field to check, null returns false
275 * @return true if the field is supported on this month-of-year, false if not
276 */
277 @Override
278 public boolean isSupported(TemporalField field) {
279 if (field instanceof ChronoField) {
280 return field == MONTH_OF_YEAR;
281 }
282 return field != null && field.isSupportedBy(this);
283 }
284
285 /**
286 * Gets the range of valid values for the specified field.
287 * <p>
288 * The range object expresses the minimum and maximum valid values for a field.
289 * This month is used to enhance the accuracy of the returned range.
290 * If it is not possible to return the range, because the field is not supported
291 * or for some other reason, an exception is thrown.
292 * <p>
293 * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the
294 * range of the month-of-year, from 1 to 12, will be returned.
295 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
296 * <p>
297 * If the field is not a {@code ChronoField}, then the result of this method
298 * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
299 * passing {@code this} as the argument.
300 * Whether the range can be obtained is determined by the field.
301 *
302 * @param field the field to query the range for, not null
303 * @return the range of valid values for the field, not null
304 * @throws DateTimeException if the range for the field cannot be obtained
305 * @throws UnsupportedTemporalTypeException if the field is not supported
306 */
307 @Override
308 public ValueRange range(TemporalField field) {
309 if (field == MONTH_OF_YEAR) {
310 return field.range();
311 }
312 return TemporalAccessor.super.range(field);
313 }
314
315 /**
316 * Gets the value of the specified field from this month-of-year as an {@code int}.
317 * <p>
318 * This queries this month for the value of the specified field.
319 * The returned value will always be within the valid range of values for the field.
320 * If it is not possible to return the value, because the field is not supported
321 * or for some other reason, an exception is thrown.
322 * <p>
323 * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the
324 * value of the month-of-year, from 1 to 12, will be returned.
325 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
326 * <p>
327 * If the field is not a {@code ChronoField}, then the result of this method
328 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
329 * passing {@code this} as the argument. Whether the value can be obtained,
330 * and what the value represents, is determined by the field.
331 *
332 * @param field the field to get, not null
333 * @return the value for the field, within the valid range of values
334 * @throws DateTimeException if a value for the field cannot be obtained or
335 * the value is outside the range of valid values for the field
336 * @throws UnsupportedTemporalTypeException if the field is not supported or
337 * the range of values exceeds an {@code int}
338 * @throws ArithmeticException if numeric overflow occurs
339 */
340 @Override
341 public int get(TemporalField field) {
342 if (field == MONTH_OF_YEAR) {
343 return getValue();
344 }
345 return TemporalAccessor.super.get(field);
346 }
347
348 /**
349 * Gets the value of the specified field from this month-of-year as a {@code long}.
350 * <p>
351 * This queries this month for the value of the specified field.
352 * If it is not possible to return the value, because the field is not supported
353 * or for some other reason, an exception is thrown.
354 * <p>
355 * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the
356 * value of the month-of-year, from 1 to 12, will be returned.
357 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
358 * <p>
359 * If the field is not a {@code ChronoField}, then the result of this method
360 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
361 * passing {@code this} as the argument. Whether the value can be obtained,
362 * and what the value represents, is determined by the field.
363 *
364 * @param field the field to get, not null
365 * @return the value for the field
366 * @throws DateTimeException if a value for the field cannot be obtained
367 * @throws UnsupportedTemporalTypeException if the field is not supported
368 * @throws ArithmeticException if numeric overflow occurs
369 */
370 @Override
371 public long getLong(TemporalField field) {
372 if (field == MONTH_OF_YEAR) {
373 return getValue();
374 } else if (field instanceof ChronoField) {
375 throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
376 }
377 return field.getFrom(this);
378 }
379
380 //-----------------------------------------------------------------------
381 /**
382 * Returns the month-of-year that is the specified number of months after this one.
383 * <p>
384 * The calculation rolls around the end of the year from December to January.
385 * The specified period may be negative.
386 * <p>
387 * This instance is immutable and unaffected by this method call.
388 *
389 * @param months the months to add, positive or negative
390 * @return the resulting month, not null
391 */
392 public Month plus(long months) {
393 int amount = (int) (months % 12);
394 return ENUMS[(ordinal() + (amount + 12)) % 12];
395 }
396
397 /**
398 * Returns the month-of-year that is the specified number of months before this one.
399 * <p>
400 * The calculation rolls around the start of the year from January to December.
401 * The specified period may be negative.
402 * <p>
403 * This instance is immutable and unaffected by this method call.
404 *
405 * @param months the months to subtract, positive or negative
406 * @return the resulting month, not null
407 */
408 public Month minus(long months) {
409 return plus(-(months % 12));
410 }
411
412 //-----------------------------------------------------------------------
413 /**
414 * Gets the length of this month in days.
415 * <p>
416 * This takes a flag to determine whether to return the length for a leap year or not.
417 * <p>
418 * February has 28 days in a standard year and 29 days in a leap year.
419 * April, June, September and November have 30 days.
420 * All other months have 31 days.
421 *
422 * @param leapYear true if the length is required for a leap year
423 * @return the length of this month in days, from 28 to 31
424 */
425 public int length(boolean leapYear) {
426 switch (this) {
427 case FEBRUARY:
428 return (leapYear ? 29 : 28);
429 case APRIL:
430 case JUNE:
431 case SEPTEMBER:
432 case NOVEMBER:
433 return 30;
434 default:
435 return 31;
436 }
437 }
438
439 /**
440 * Gets the minimum length of this month in days.
441 * <p>
442 * February has a minimum length of 28 days.
443 * April, June, September and November have 30 days.
444 * All other months have 31 days.
445 *
446 * @return the minimum length of this month in days, from 28 to 31
447 */
448 public int minLength() {
449 switch (this) {
450 case FEBRUARY:
451 return 28;
452 case APRIL:
453 case JUNE:
454 case SEPTEMBER:
455 case NOVEMBER:
456 return 30;
457 default:
458 return 31;
459 }
460 }
461
462 /**
463 * Gets the maximum length of this month in days.
464 * <p>
465 * February has a maximum length of 29 days.
466 * April, June, September and November have 30 days.
467 * All other months have 31 days.
468 *
469 * @return the maximum length of this month in days, from 29 to 31
470 */
471 public int maxLength() {
472 switch (this) {
473 case FEBRUARY:
474 return 29;
475 case APRIL:
476 case JUNE:
477 case SEPTEMBER:
478 case NOVEMBER:
479 return 30;
480 default:
481 return 31;
482 }
483 }
484
485 //-----------------------------------------------------------------------
486 /**
487 * Gets the day-of-year corresponding to the first day of this month.
488 * <p>
489 * This returns the day-of-year that this month begins on, using the leap
490 * year flag to determine the length of February.
491 *
492 * @param leapYear true if the length is required for a leap year
493 * @return the day of year corresponding to the first day of this month, from 1 to 336
494 */
495 public int firstDayOfYear(boolean leapYear) {
496 int leap = leapYear ? 1 : 0;
497 switch (this) {
498 case JANUARY:
499 return 1;
500 case FEBRUARY:
501 return 32;
502 case MARCH:
503 return 60 + leap;
504 case APRIL:
505 return 91 + leap;
506 case MAY:
507 return 121 + leap;
508 case JUNE:
509 return 152 + leap;
510 case JULY:
511 return 182 + leap;
512 case AUGUST:
513 return 213 + leap;
514 case SEPTEMBER:
515 return 244 + leap;
516 case OCTOBER:
517 return 274 + leap;
518 case NOVEMBER:
519 return 305 + leap;
520 case DECEMBER:
521 default:
522 return 335 + leap;
523 }
524 }
525
526 /**
527 * Gets the month corresponding to the first month of this quarter.
528 * <p>
529 * The year can be divided into four quarters.
530 * This method returns the first month of the quarter for the base month.
531 * January, February and March return January.
532 * April, May and June return April.
533 * July, August and September return July.
534 * October, November and December return October.
535 *
536 * @return the first month of the quarter corresponding to this month, not null
537 */
538 public Month firstMonthOfQuarter() {
539 return ENUMS[(ordinal() / 3) * 3];
540 }
541
542 //-----------------------------------------------------------------------
543 /**
544 * Queries this month-of-year using the specified query.
545 * <p>
546 * This queries this month-of-year using the specified query strategy object.
547 * The {@code TemporalQuery} object defines the logic to be used to
548 * obtain the result. Read the documentation of the query to understand
549 * what the result of this method will be.
550 * <p>
551 * The result of this method is obtained by invoking the
552 * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
553 * specified query passing {@code this} as the argument.
554 *
555 * @param <R> the type of the result
556 * @param query the query to invoke, not null
557 * @return the query result, null may be returned (defined by the query)
558 * @throws DateTimeException if unable to query (defined by the query)
559 * @throws ArithmeticException if numeric overflow occurs (defined by the query)
560 */
561 @SuppressWarnings("unchecked")
562 @Override
563 public <R> R query(TemporalQuery<R> query) {
564 if (query == TemporalQueries.chronology()) {
565 return (R) IsoChronology.INSTANCE;
566 } else if (query == TemporalQueries.precision()) {
567 return (R) MONTHS;
568 }
569 return TemporalAccessor.super.query(query);
570 }
571
572 /**
573 * Adjusts the specified temporal object to have this month-of-year.
574 * <p>
575 * This returns a temporal object of the same observable type as the input
576 * with the month-of-year changed to be the same as this.
577 * <p>
578 * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
579 * passing {@link ChronoField#MONTH_OF_YEAR} as the field.
580 * If the specified temporal object does not use the ISO calendar system then
581 * a {@code DateTimeException} is thrown.
582 * <p>
583 * In most cases, it is clearer to reverse the calling pattern by using
584 * {@link Temporal#with(TemporalAdjuster)}:
585 * <pre>
586 * // these two lines are equivalent, but the second approach is recommended
587 * temporal = thisMonth.adjustInto(temporal);
588 * temporal = temporal.with(thisMonth);
589 * </pre>
590 * <p>
591 * For example, given a date in May, the following are output:
592 * <pre>
593 * dateInMay.with(JANUARY); // four months earlier
594 * dateInMay.with(APRIL); // one months earlier
595 * dateInMay.with(MAY); // same date
596 * dateInMay.with(JUNE); // one month later
597 * dateInMay.with(DECEMBER); // seven months later
598 * </pre>
599 * <p>
600 * This instance is immutable and unaffected by this method call.
601 *
602 * @param temporal the target object to be adjusted, not null
603 * @return the adjusted object, not null
604 * @throws DateTimeException if unable to make the adjustment
605 * @throws ArithmeticException if numeric overflow occurs
606 */
607 @Override
608 public Temporal adjustInto(Temporal temporal) {
609 if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) {
610 throw new DateTimeException("Adjustment only supported on ISO date-time");
611 }
612 return temporal.with(MONTH_OF_YEAR, getValue());
613 }
614
615 }
616