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).
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17 * You should have received a copy of the GNU General Public License version
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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) 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.chrono;
63
64 import static java.time.temporal.ChronoField.EPOCH_DAY;
65 import static java.time.temporal.ChronoField.ERA;
66 import static java.time.temporal.ChronoField.YEAR;
67 import static java.time.temporal.ChronoUnit.DAYS;
68
69 import java.time.DateTimeException;
70 import java.time.LocalDate;
71 import java.time.LocalTime;
72 import java.time.Period;
73 import java.time.format.DateTimeFormatter;
74 import java.time.temporal.ChronoField;
75 import java.time.temporal.ChronoUnit;
76 import java.time.temporal.Temporal;
77 import java.time.temporal.TemporalAccessor;
78 import java.time.temporal.TemporalAdjuster;
79 import java.time.temporal.TemporalAmount;
80 import java.time.temporal.TemporalField;
81 import java.time.temporal.TemporalQuery;
82 import java.time.temporal.TemporalUnit;
83 import java.time.temporal.UnsupportedTemporalTypeException;
84 import java.util.Comparator;
85 import java.util.Objects;
86
87 /**
88 * A date without time-of-day or time-zone in an arbitrary chronology, intended
89 * for advanced globalization use cases.
90 * <p>
91 * <b>Most applications should declare method signatures, fields and variables
92 * as {@link LocalDate}, not this interface.</b>
93 * <p>
94 * A {@code ChronoLocalDate} is the abstract representation of a date where the
95 * {@code Chronology chronology}, or calendar system, is pluggable.
96 * The date is defined in terms of fields expressed by {@link TemporalField},
97 * where most common implementations are defined in {@link ChronoField}.
98 * The chronology defines how the calendar system operates and the meaning of
99 * the standard fields.
100 *
101 * <h3>When to use this interface</h3>
102 * The design of the API encourages the use of {@code LocalDate} rather than this
103 * interface, even in the case where the application needs to deal with multiple
104 * calendar systems. The rationale for this is explored in the following documentation.
105 * <p>
106 * The primary use case where this interface should be used is where the generic
107 * type parameter {@code <D>} is fully defined as a specific chronology.
108 * In that case, the assumptions of that chronology are known at development
109 * time and specified in the code.
110 * <p>
111 * When the chronology is defined in the generic type parameter as ? or otherwise
112 * unknown at development time, the rest of the discussion below applies.
113 * <p>
114 * To emphasize the point, declaring a method signature, field or variable as this
115 * interface type can initially seem like the sensible way to globalize an application,
116 * however it is usually the wrong approach.
117 * As such, it should be considered an application-wide architectural decision to choose
118 * to use this interface as opposed to {@code LocalDate}.
119 *
120 * <h3>Architectural issues to consider</h3>
121 * These are some of the points that must be considered before using this interface
122 * throughout an application.
123 * <p>
124 * 1) Applications using this interface, as opposed to using just {@code LocalDate},
125 * face a significantly higher probability of bugs. This is because the calendar system
126 * in use is not known at development time. A key cause of bugs is where the developer
127 * applies assumptions from their day-to-day knowledge of the ISO calendar system
128 * to code that is intended to deal with any arbitrary calendar system.
129 * The section below outlines how those assumptions can cause problems
130 * The primary mechanism for reducing this increased risk of bugs is a strong code review process.
131 * This should also be considered a extra cost in maintenance for the lifetime of the code.
132 * <p>
133 * 2) This interface does not enforce immutability of implementations.
134 * While the implementation notes indicate that all implementations must be immutable
135 * there is nothing in the code or type system to enforce this. Any method declared
136 * to accept a {@code ChronoLocalDate} could therefore be passed a poorly or
137 * maliciously written mutable implementation.
138 * <p>
139 * 3) Applications using this interface must consider the impact of eras.
140 * {@code LocalDate} shields users from the concept of eras, by ensuring that {@code getYear()}
141 * returns the proleptic year. That decision ensures that developers can think of
142 * {@code LocalDate} instances as consisting of three fields - year, month-of-year and day-of-month.
143 * By contrast, users of this interface must think of dates as consisting of four fields -
144 * era, year-of-era, month-of-year and day-of-month. The extra era field is frequently
145 * forgotten, yet it is of vital importance to dates in an arbitrary calendar system.
146 * For example, in the Japanese calendar system, the era represents the reign of an Emperor.
147 * Whenever one reign ends and another starts, the year-of-era is reset to one.
148 * <p>
149 * 4) The only agreed international standard for passing a date between two systems
150 * is the ISO-8601 standard which requires the ISO calendar system. Using this interface
151 * throughout the application will inevitably lead to the requirement to pass the date
152 * across a network or component boundary, requiring an application specific protocol or format.
153 * <p>
154 * 5) Long term persistence, such as a database, will almost always only accept dates in the
155 * ISO-8601 calendar system (or the related Julian-Gregorian). Passing around dates in other
156 * calendar systems increases the complications of interacting with persistence.
157 * <p>
158 * 6) Most of the time, passing a {@code ChronoLocalDate} throughout an application
159 * is unnecessary, as discussed in the last section below.
160 *
161 * <h3>False assumptions causing bugs in multi-calendar system code</h3>
162 * As indicated above, there are many issues to consider when try to use and manipulate a
163 * date in an arbitrary calendar system. These are some of the key issues.
164 * <p>
165 * Code that queries the day-of-month and assumes that the value will never be more than
166 * 31 is invalid. Some calendar systems have more than 31 days in some months.
167 * <p>
168 * Code that adds 12 months to a date and assumes that a year has been added is invalid.
169 * Some calendar systems have a different number of months, such as 13 in the Coptic or Ethiopic.
170 * <p>
171 * Code that adds one month to a date and assumes that the month-of-year value will increase
172 * by one or wrap to the next year is invalid. Some calendar systems have a variable number
173 * of months in a year, such as the Hebrew.
174 * <p>
175 * Code that adds one month, then adds a second one month and assumes that the day-of-month
176 * will remain close to its original value is invalid. Some calendar systems have a large difference
177 * between the length of the longest month and the length of the shortest month.
178 * For example, the Coptic or Ethiopic have 12 months of 30 days and 1 month of 5 days.
179 * <p>
180 * Code that adds seven days and assumes that a week has been added is invalid.
181 * Some calendar systems have weeks of other than seven days, such as the French Revolutionary.
182 * <p>
183 * Code that assumes that because the year of {@code date1} is greater than the year of {@code date2}
184 * then {@code date1} is after {@code date2} is invalid. This is invalid for all calendar systems
185 * when referring to the year-of-era, and especially untrue of the Japanese calendar system
186 * where the year-of-era restarts with the reign of every new Emperor.
187 * <p>
188 * Code that treats month-of-year one and day-of-month one as the start of the year is invalid.
189 * Not all calendar systems start the year when the month value is one.
190 * <p>
191 * In general, manipulating a date, and even querying a date, is wide open to bugs when the
192 * calendar system is unknown at development time. This is why it is essential that code using
193 * this interface is subjected to additional code reviews. It is also why an architectural
194 * decision to avoid this interface type is usually the correct one.
195 *
196 * <h3>Using LocalDate instead</h3>
197 * The primary alternative to using this interface throughout your application is as follows.
198 * <p><ul>
199 * <li>Declare all method signatures referring to dates in terms of {@code LocalDate}.
200 * <li>Either store the chronology (calendar system) in the user profile or lookup
201 * the chronology from the user locale
202 * <li>Convert the ISO {@code LocalDate} to and from the user's preferred calendar system during
203 * printing and parsing
204 * </ul><p>
205 * This approach treats the problem of globalized calendar systems as a localization issue
206 * and confines it to the UI layer. This approach is in keeping with other localization
207 * issues in the java platform.
208 * <p>
209 * As discussed above, performing calculations on a date where the rules of the calendar system
210 * are pluggable requires skill and is not recommended.
211 * Fortunately, the need to perform calculations on a date in an arbitrary calendar system
212 * is extremely rare. For example, it is highly unlikely that the business rules of a library
213 * book rental scheme will allow rentals to be for one month, where meaning of the month
214 * is dependent on the user's preferred calendar system.
215 * <p>
216 * A key use case for calculations on a date in an arbitrary calendar system is producing
217 * a month-by-month calendar for display and user interaction. Again, this is a UI issue,
218 * and use of this interface solely within a few methods of the UI layer may be justified.
219 * <p>
220 * In any other part of the system, where a date must be manipulated in a calendar system
221 * other than ISO, the use case will generally specify the calendar system to use.
222 * For example, an application may need to calculate the next Islamic or Hebrew holiday
223 * which may require manipulating the date.
224 * This kind of use case can be handled as follows:
225 * <p><ul>
226 * <li>start from the ISO {@code LocalDate} being passed to the method
227 * <li>convert the date to the alternate calendar system, which for this use case is known
228 * rather than arbitrary
229 * <li>perform the calculation
230 * <li>convert back to {@code LocalDate}
231 * </ul><p>
232 * Developers writing low-level frameworks or libraries should also avoid this interface.
233 * Instead, one of the two general purpose access interfaces should be used.
234 * Use {@link TemporalAccessor} if read-only access is required, or use {@link Temporal}
235 * if read-write access is required.
236 *
237 * @implSpec
238 * This interface must be implemented with care to ensure other classes operate correctly.
239 * All implementations that can be instantiated must be final, immutable and thread-safe.
240 * Subclasses should be Serializable wherever possible.
241 * <p>
242 * Additional calendar systems may be added to the system.
243 * See {@link Chronology} for more details.
244 *
245 * @param <D> the concrete type for the date
246 * @since 1.8
247 */
248 public interface ChronoLocalDate<D extends ChronoLocalDate<D>>
249 extends Temporal, TemporalAdjuster, Comparable<ChronoLocalDate<?>> {
250
251 /**
252 * Gets a comparator that compares {@code ChronoLocalDate} in
253 * time-line order ignoring the chronology.
254 * <p>
255 * This comparator differs from the comparison in {@link #compareTo} in that it
256 * only compares the underlying date and not the chronology.
257 * This allows dates in different calendar systems to be compared based
258 * on the position of the date on the local time-line.
259 * The underlying comparison is equivalent to comparing the epoch-day.
260 * @return a comparator that compares in time-line order ignoring the chronology
261 *
262 * @see #isAfter
263 * @see #isBefore
264 * @see #isEqual
265 */
266 static Comparator<ChronoLocalDate<?>> timeLineOrder() {
267 return Chronology.DATE_ORDER;
268 }
269
270 //-----------------------------------------------------------------------
271 /**
272 * Obtains an instance of {@code ChronoLocalDate} from a temporal object.
273 * <p>
274 * This obtains a local date based on the specified temporal.
275 * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
276 * which this factory converts to an instance of {@code ChronoLocalDate}.
277 * <p>
278 * The conversion extracts and combines the chronology and the date
279 * from the temporal object. The behavior is equivalent to using
280 * {@link Chronology#date(TemporalAccessor)} with the extracted chronology.
281 * Implementations are permitted to perform optimizations such as accessing
282 * those fields that are equivalent to the relevant objects.
283 * <p>
284 * This method matches the signature of the functional interface {@link TemporalQuery}
285 * allowing it to be used as a query via method reference, {@code ChronoLocalDate::from}.
286 *
287 * @param temporal the temporal object to convert, not null
288 * @return the date, not null
289 * @throws DateTimeException if unable to convert to a {@code ChronoLocalDate}
290 * @see Chronology#date(TemporalAccessor)
291 */
292 static ChronoLocalDate<?> from(TemporalAccessor temporal) {
293 if (temporal instanceof ChronoLocalDate) {
294 return (ChronoLocalDate<?>) temporal;
295 }
296 Chronology chrono = temporal.query(TemporalQuery.chronology());
297 if (chrono == null) {
298 throw new DateTimeException("Unable to obtain ChronoLocalDate from TemporalAccessor: " + temporal.getClass());
299 }
300 return chrono.date(temporal);
301 }
302
303 //-----------------------------------------------------------------------
304 /**
305 * Gets the chronology of this date.
306 * <p>
307 * The {@code Chronology} represents the calendar system in use.
308 * The era and other fields in {@link ChronoField} are defined by the chronology.
309 *
310 * @return the chronology, not null
311 */
312 Chronology getChronology();
313
314 /**
315 * Gets the era, as defined by the chronology.
316 * <p>
317 * The era is, conceptually, the largest division of the time-line.
318 * Most calendar systems have a single epoch dividing the time-line into two eras.
319 * However, some have multiple eras, such as one for the reign of each leader.
320 * The exact meaning is determined by the {@code Chronology}.
321 * <p>
322 * All correctly implemented {@code Era} classes are singletons, thus it
323 * is valid code to write {@code date.getEra() == SomeChrono.ERA_NAME)}.
324 * <p>
325 * This default implementation uses {@link Chronology#eraOf(int)}.
326 *
327 * @return the chronology specific era constant applicable at this date, not null
328 */
329 default Era getEra() {
330 return getChronology().eraOf(get(ERA));
331 }
332
333 /**
334 * Checks if the year is a leap year, as defined by the calendar system.
335 * <p>
336 * A leap-year is a year of a longer length than normal.
337 * The exact meaning is determined by the chronology with the constraint that
338 * a leap-year must imply a year-length longer than a non leap-year.
339 * <p>
340 * This default implementation uses {@link Chronology#isLeapYear(long)}.
341 *
342 * @return true if this date is in a leap year, false otherwise
343 */
344 default boolean isLeapYear() {
345 return getChronology().isLeapYear(getLong(YEAR));
346 }
347
348 /**
349 * Returns the length of the month represented by this date, as defined by the calendar system.
350 * <p>
351 * This returns the length of the month in days.
352 *
353 * @return the length of the month in days
354 */
355 int lengthOfMonth();
356
357 /**
358 * Returns the length of the year represented by this date, as defined by the calendar system.
359 * <p>
360 * This returns the length of the year in days.
361 * <p>
362 * The default implementation uses {@link #isLeapYear()} and returns 365 or 366.
363 *
364 * @return the length of the year in days
365 */
366 default int lengthOfYear() {
367 return (isLeapYear() ? 366 : 365);
368 }
369
370 @Override
371 default boolean isSupported(TemporalField field) {
372 if (field instanceof ChronoField) {
373 return field.isDateBased();
374 }
375 return field != null && field.isSupportedBy(this);
376 }
377
378 //-----------------------------------------------------------------------
379 // override for covariant return type
380 /**
381 * {@inheritDoc}
382 * @throws DateTimeException {@inheritDoc}
383 * @throws ArithmeticException {@inheritDoc}
384 */
385 @Override
386 default D with(TemporalAdjuster adjuster) {
387 return (D) getChronology().ensureChronoLocalDate(Temporal.super.with(adjuster));
388 }
389
390 /**
391 * {@inheritDoc}
392 * @throws DateTimeException {@inheritDoc}
393 * @throws UnsupportedTemporalTypeException {@inheritDoc}
394 * @throws ArithmeticException {@inheritDoc}
395 */
396 @Override
397 default D with(TemporalField field, long newValue) {
398 if (field instanceof ChronoField) {
399 throw new UnsupportedTemporalTypeException("Unsupported field: " + field.getName());
400 }
401 return (D) getChronology().ensureChronoLocalDate(field.adjustInto(this, newValue));
402 }
403
404 /**
405 * {@inheritDoc}
406 * @throws DateTimeException {@inheritDoc}
407 * @throws ArithmeticException {@inheritDoc}
408 */
409 @Override
410 default D plus(TemporalAmount amount) {
411 return (D) getChronology().ensureChronoLocalDate(Temporal.super.plus(amount));
412 }
413
414 /**
415 * {@inheritDoc}
416 * @throws DateTimeException {@inheritDoc}
417 * @throws ArithmeticException {@inheritDoc}
418 */
419 @Override
420 default D plus(long amountToAdd, TemporalUnit unit) {
421 if (unit instanceof ChronoUnit) {
422 throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit.getName());
423 }
424 return (D) getChronology().ensureChronoLocalDate(unit.addTo(this, amountToAdd));
425 }
426
427 /**
428 * {@inheritDoc}
429 * @throws DateTimeException {@inheritDoc}
430 * @throws ArithmeticException {@inheritDoc}
431 */
432 @Override
433 default D minus(TemporalAmount amount) {
434 return (D) getChronology().ensureChronoLocalDate(Temporal.super.minus(amount));
435 }
436
437 /**
438 * {@inheritDoc}
439 * @throws DateTimeException {@inheritDoc}
440 * @throws UnsupportedTemporalTypeException {@inheritDoc}
441 * @throws ArithmeticException {@inheritDoc}
442 */
443 @Override
444 default D minus(long amountToSubtract, TemporalUnit unit) {
445 return (D) getChronology().ensureChronoLocalDate(Temporal.super.minus(amountToSubtract, unit));
446 }
447
448 //-----------------------------------------------------------------------
449 /**
450 * Queries this date using the specified query.
451 * <p>
452 * This queries this date using the specified query strategy object.
453 * The {@code TemporalQuery} object defines the logic to be used to
454 * obtain the result. Read the documentation of the query to understand
455 * what the result of this method will be.
456 * <p>
457 * The result of this method is obtained by invoking the
458 * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
459 * specified query passing {@code this} as the argument.
460 *
461 * @param <R> the type of the result
462 * @param query the query to invoke, not null
463 * @return the query result, null may be returned (defined by the query)
464 * @throws DateTimeException if unable to query (defined by the query)
465 * @throws ArithmeticException if numeric overflow occurs (defined by the query)
466 */
467 @SuppressWarnings("unchecked")
468 @Override
469 default <R> R query(TemporalQuery<R> query) {
470 if (query == TemporalQuery.zoneId() || query == TemporalQuery.zone() || query == TemporalQuery.offset()) {
471 return null;
472 } else if (query == TemporalQuery.localTime()) {
473 return null;
474 } else if (query == TemporalQuery.chronology()) {
475 return (R) getChronology();
476 } else if (query == TemporalQuery.precision()) {
477 return (R) DAYS;
478 }
479 // inline TemporalAccessor.super.query(query) as an optimization
480 // non-JDK classes are not permitted to make this optimization
481 return query.queryFrom(this);
482 }
483
484 /**
485 * Adjusts the specified temporal object to have the same date as this object.
486 * <p>
487 * This returns a temporal object of the same observable type as the input
488 * with the date changed to be the same as this.
489 * <p>
490 * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
491 * passing {@link ChronoField#EPOCH_DAY} as the field.
492 * <p>
493 * In most cases, it is clearer to reverse the calling pattern by using
494 * {@link Temporal#with(TemporalAdjuster)}:
495 * <pre>
496 * // these two lines are equivalent, but the second approach is recommended
497 * temporal = thisLocalDate.adjustInto(temporal);
498 * temporal = temporal.with(thisLocalDate);
499 * </pre>
500 * <p>
501 * This instance is immutable and unaffected by this method call.
502 *
503 * @param temporal the target object to be adjusted, not null
504 * @return the adjusted object, not null
505 * @throws DateTimeException if unable to make the adjustment
506 * @throws ArithmeticException if numeric overflow occurs
507 */
508 @Override
509 default Temporal adjustInto(Temporal temporal) {
510 return temporal.with(EPOCH_DAY, toEpochDay());
511 }
512
513 /**
514 * Calculates the amount of time until another date in terms of the specified unit.
515 * <p>
516 * This calculates the amount of time between two {@code ChronoLocalDate}
517 * objects in terms of a single {@code TemporalUnit}.
518 * The start and end points are {@code this} and the specified date.
519 * The result will be negative if the end is before the start.
520 * The {@code Temporal} passed to this method must be a
521 * {@code ChronoLocalDate} in the same chronology.
522 * The calculation returns a whole number, representing the number of
523 * complete units between the two dates.
524 * For example, the amount in days between two dates can be calculated
525 * using {@code startDate.periodUntil(endDate, DAYS)}.
526 * <p>
527 * There are two equivalent ways of using this method.
528 * The first is to invoke this method.
529 * The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:
530 * <pre>
531 * // these two lines are equivalent
532 * amount = start.periodUntil(end, MONTHS);
533 * amount = MONTHS.between(start, end);
534 * </pre>
535 * The choice should be made based on which makes the code more readable.
536 * <p>
537 * The calculation is implemented in this method for {@link ChronoUnit}.
538 * The units {@code DAYS}, {@code WEEKS}, {@code MONTHS}, {@code YEARS},
539 * {@code DECADES}, {@code CENTURIES}, {@code MILLENNIA} and {@code ERAS}
540 * should be supported by all implementations.
541 * Other {@code ChronoUnit} values will throw an exception.
542 * <p>
543 * If the unit is not a {@code ChronoUnit}, then the result of this method
544 * is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
545 * passing {@code this} as the first argument and the input temporal as
546 * the second argument.
547 * <p>
548 * This instance is immutable and unaffected by this method call.
549 *
550 * @param endDate the end date, which must be a {@code ChronoLocalDate}
551 * in the same chronology, not null
552 * @param unit the unit to measure the amount in, not null
553 * @return the amount of time between this date and the end date
554 * @throws DateTimeException if the amount cannot be calculated
555 * @throws ArithmeticException if numeric overflow occurs
556 */
557 @Override // override for Javadoc
558 long periodUntil(Temporal endDate, TemporalUnit unit);
559
560 /**
561 * Calculates the period between this date and another date as a {@code Period}.
562 * <p>
563 * This calculates the period between two dates in terms of years, months and days.
564 * The start and end points are {@code this} and the specified date.
565 * The result will be negative if the end is before the start.
566 * The negative sign will be the same in each of year, month and day.
567 * <p>
568 * The calculation is performed using the chronology of this date.
569 * If necessary, the input date will be converted to match.
570 * <p>
571 * This instance is immutable and unaffected by this method call.
572 *
573 * @param endDate the end date, exclusive, which may be in any chronology, not null
574 * @return the period between this date and the end date, not null
575 * @throws DateTimeException if the period cannot be calculated
576 * @throws ArithmeticException if numeric overflow occurs
577 */
578 Period periodUntil(ChronoLocalDate<?> endDate);
579
580 /**
581 * Formats this date using the specified formatter.
582 * <p>
583 * This date will be passed to the formatter to produce a string.
584 * <p>
585 * The default implementation must behave as follows:
586 * <pre>
587 * return formatter.format(this);
588 * </pre>
589 *
590 * @param formatter the formatter to use, not null
591 * @return the formatted date string, not null
592 * @throws DateTimeException if an error occurs during printing
593 */
594 default String format(DateTimeFormatter formatter) {
595 Objects.requireNonNull(formatter, "formatter");
596 return formatter.format(this);
597 }
598
599 //-----------------------------------------------------------------------
600 /**
601 * Combines this date with a time to create a {@code ChronoLocalDateTime}.
602 * <p>
603 * This returns a {@code ChronoLocalDateTime} formed from this date at the specified time.
604 * All possible combinations of date and time are valid.
605 *
606 * @param localTime the local time to use, not null
607 * @return the local date-time formed from this date and the specified time, not null
608 */
609 default ChronoLocalDateTime<D> atTime(LocalTime localTime) {
610 return (ChronoLocalDateTime<D>)ChronoLocalDateTimeImpl.of(this, localTime);
611 }
612
613 //-----------------------------------------------------------------------
614 /**
615 * Converts this date to the Epoch Day.
616 * <p>
617 * The {@link ChronoField#EPOCH_DAY Epoch Day count} is a simple
618 * incrementing count of days where day 0 is 1970-01-01 (ISO).
619 * This definition is the same for all chronologies, enabling conversion.
620 * <p>
621 * This default implementation queries the {@code EPOCH_DAY} field.
622 *
623 * @return the Epoch Day equivalent to this date
624 */
625 default long toEpochDay() {
626 return getLong(EPOCH_DAY);
627 }
628
629 //-----------------------------------------------------------------------
630 /**
631 * Compares this date to another date, including the chronology.
632 * <p>
633 * The comparison is based first on the underlying time-line date, then
634 * on the chronology.
635 * It is "consistent with equals", as defined by {@link Comparable}.
636 * <p>
637 * For example, the following is the comparator order:
638 * <ol>
639 * <li>{@code 2012-12-03 (ISO)}</li>
640 * <li>{@code 2012-12-04 (ISO)}</li>
641 * <li>{@code 2555-12-04 (ThaiBuddhist)}</li>
642 * <li>{@code 2012-12-05 (ISO)}</li>
643 * </ol>
644 * Values #2 and #3 represent the same date on the time-line.
645 * When two values represent the same date, the chronology ID is compared to distinguish them.
646 * This step is needed to make the ordering "consistent with equals".
647 * <p>
648 * If all the date objects being compared are in the same chronology, then the
649 * additional chronology stage is not required and only the local date is used.
650 * To compare the dates of two {@code TemporalAccessor} instances, including dates
651 * in two different chronologies, use {@link ChronoField#EPOCH_DAY} as a comparator.
652 * <p>
653 * This default implementation performs the comparison defined above.
654 *
655 * @param other the other date to compare to, not null
656 * @return the comparator value, negative if less, positive if greater
657 */
658 @Override
659 default int compareTo(ChronoLocalDate<?> other) {
660 int cmp = Long.compare(toEpochDay(), other.toEpochDay());
661 if (cmp == 0) {
662 cmp = getChronology().compareTo(other.getChronology());
663 }
664 return cmp;
665 }
666
667 /**
668 * Checks if this date is after the specified date ignoring the chronology.
669 * <p>
670 * This method differs from the comparison in {@link #compareTo} in that it
671 * only compares the underlying date and not the chronology.
672 * This allows dates in different calendar systems to be compared based
673 * on the time-line position.
674 * This is equivalent to using {@code date1.toEpochDay() > date2.toEpochDay()}.
675 * <p>
676 * This default implementation performs the comparison based on the epoch-day.
677 *
678 * @param other the other date to compare to, not null
679 * @return true if this is after the specified date
680 */
681 default boolean isAfter(ChronoLocalDate<?> other) {
682 return this.toEpochDay() > other.toEpochDay();
683 }
684
685 /**
686 * Checks if this date is before the specified date ignoring the chronology.
687 * <p>
688 * This method differs from the comparison in {@link #compareTo} in that it
689 * only compares the underlying date and not the chronology.
690 * This allows dates in different calendar systems to be compared based
691 * on the time-line position.
692 * This is equivalent to using {@code date1.toEpochDay() < date2.toEpochDay()}.
693 * <p>
694 * This default implementation performs the comparison based on the epoch-day.
695 *
696 * @param other the other date to compare to, not null
697 * @return true if this is before the specified date
698 */
699 default boolean isBefore(ChronoLocalDate<?> other) {
700 return this.toEpochDay() < other.toEpochDay();
701 }
702
703 /**
704 * Checks if this date is equal to the specified date ignoring the chronology.
705 * <p>
706 * This method differs from the comparison in {@link #compareTo} in that it
707 * only compares the underlying date and not the chronology.
708 * This allows dates in different calendar systems to be compared based
709 * on the time-line position.
710 * This is equivalent to using {@code date1.toEpochDay() == date2.toEpochDay()}.
711 * <p>
712 * This default implementation performs the comparison based on the epoch-day.
713 *
714 * @param other the other date to compare to, not null
715 * @return true if the underlying date is equal to the specified date
716 */
717 default boolean isEqual(ChronoLocalDate<?> other) {
718 return this.toEpochDay() == other.toEpochDay();
719 }
720
721 //-----------------------------------------------------------------------
722 /**
723 * Checks if this date is equal to another date, including the chronology.
724 * <p>
725 * Compares this date with another ensuring that the date and chronology are the same.
726 * <p>
727 * To compare the dates of two {@code TemporalAccessor} instances, including dates
728 * in two different chronologies, use {@link ChronoField#EPOCH_DAY} as a comparator.
729 *
730 * @param obj the object to check, null returns false
731 * @return true if this is equal to the other date
732 */
733 @Override
734 boolean equals(Object obj);
735
736 /**
737 * A hash code for this date.
738 *
739 * @return a suitable hash code
740 */
741 @Override
742 int hashCode();
743
744 //-----------------------------------------------------------------------
745 /**
746 * Outputs this date as a {@code String}.
747 * <p>
748 * The output will include the full local date.
749 *
750 * @return the formatted date, not null
751 */
752 @Override
753 String toString();
754
755 }