1 /*
2 * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 /*
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file:
31 *
32 * Copyright (c) 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 java.io.Serializable;
65 import java.time.Clock;
66 import java.time.DateTimeException;
67 import java.time.Instant;
68 import java.time.LocalDate;
69 import java.time.LocalDateTime;
70 import java.time.ZoneId;
71 import java.time.ZonedDateTime;
72 import java.time.temporal.ChronoField;
73 import java.time.temporal.TemporalAccessor;
74 import java.time.temporal.ValueRange;
75 import java.util.Arrays;
76 import java.util.List;
77 import java.util.Locale;
78 import java.util.Objects;
79
80 /**
81 * The ISO calendar system.
82 * <p>
83 * This chronology defines the rules of the ISO calendar system.
84 * This calendar system is based on the ISO-8601 standard, which is the
85 * <i>de facto</i> world calendar.
86 * <p>
87 * The fields are defined as follows:
88 * <p><ul>
89 * <li>era - There are two eras, 'Current Era' (CE) and 'Before Current Era' (BCE).
90 * <li>year-of-era - The year-of-era is the same as the proleptic-year for the current CE era.
91 * For the BCE era before the ISO epoch the year increases from 1 upwards as time goes backwards.
92 * <li>proleptic-year - The proleptic year is the same as the year-of-era for the
93 * current era. For the previous era, years have zero, then negative values.
94 * <li>month-of-year - There are 12 months in an ISO year, numbered from 1 to 12.
95 * <li>day-of-month - There are between 28 and 31 days in each of the ISO month, numbered from 1 to 31.
96 * Months 4, 6, 9 and 11 have 30 days, Months 1, 3, 5, 7, 8, 10 and 12 have 31 days.
97 * Month 2 has 28 days, or 29 in a leap year.
98 * <li>day-of-year - There are 365 days in a standard ISO year and 366 in a leap year.
99 * The days are numbered from 1 to 365 or 1 to 366.
100 * <li>leap-year - Leap years occur every 4 years, except where the year is divisble by 100 and not divisble by 400.
101 * </ul><p>
102 *
103 * <h3>Specification for implementors</h3>
104 * This class is immutable and thread-safe.
105 *
106 * @since 1.8
107 */
108 public final class IsoChronology extends Chronology implements Serializable {
109
110 /**
111 * Singleton instance of the ISO chronology.
112 */
113 public static final IsoChronology INSTANCE = new IsoChronology();
114 /**
115 * The singleton instance for the era BCE - 'Before Current Era'.
116 * The 'ISO' part of the name emphasizes that this differs from the BCE
117 * era in the Gregorian calendar system.
118 * This has the numeric value of {@code 0}.
119 */
120 public static final Era ERA_BCE = IsoEra.BCE;
121 /**
122 * The singleton instance for the era CE - 'Current Era'.
123 * The 'ISO' part of the name emphasizes that this differs from the CE
124 * era in the Gregorian calendar system.
125 * This has the numeric value of {@code 1}.
126 */
127 public static final Era ERA_CE = IsoEra.CE;
128
129 /**
130 * Serialization version.
131 */
132 private static final long serialVersionUID = -1440403870442975015L;
133
134 /**
135 * Restricted constructor.
136 */
137 private IsoChronology() {
138 }
139
140 /**
141 * Resolve singleton.
142 *
143 * @return the singleton instance, not null
144 */
145 private Object readResolve() {
146 return INSTANCE;
147 }
148
149 //-----------------------------------------------------------------------
150 /**
151 * Gets the ID of the chronology - 'ISO'.
152 * <p>
153 * The ID uniquely identifies the {@code Chronology}.
154 * It can be used to lookup the {@code Chronology} using {@link #of(String)}.
155 *
156 * @return the chronology ID - 'ISO'
157 * @see #getCalendarType()
158 */
159 @Override
160 public String getId() {
161 return "ISO";
162 }
163
164 /**
165 * Gets the calendar type of the underlying calendar system - 'iso8601'.
166 * <p>
167 * The calendar type is an identifier defined by the
168 * <em>Unicode Locale Data Markup Language (LDML)</em> specification.
169 * It can be used to lookup the {@code Chronology} using {@link #of(String)}.
170 * It can also be used as part of a locale, accessible via
171 * {@link Locale#getUnicodeLocaleType(String)} with the key 'ca'.
172 *
173 * @return the calendar system type - 'iso8601'
174 * @see #getId()
175 */
176 @Override
177 public String getCalendarType() {
178 return "iso8601";
179 }
180
181 //-----------------------------------------------------------------------
182 /**
183 * Obtains an ISO local date from the era, year-of-era, month-of-year
184 * and day-of-month fields.
185 *
186 * @param era the ISO era, not null
187 * @param yearOfEra the ISO year-of-era
188 * @param month the ISO month-of-year
189 * @param dayOfMonth the ISO day-of-month
190 * @return the ISO local date, not null
191 * @throws DateTimeException if unable to create the date
192 */
193 @Override // override with covariant return type
194 public LocalDate date(Era era, int yearOfEra, int month, int dayOfMonth) {
195 return date(prolepticYear(era, yearOfEra), month, dayOfMonth);
196 }
197
198 /**
199 * Obtains an ISO local date from the proleptic-year, month-of-year
200 * and day-of-month fields.
201 * <p>
202 * This is equivalent to {@link LocalDate#of(int, int, int)}.
203 *
204 * @param prolepticYear the ISO proleptic-year
205 * @param month the ISO month-of-year
206 * @param dayOfMonth the ISO day-of-month
207 * @return the ISO local date, not null
208 * @throws DateTimeException if unable to create the date
209 */
210 @Override // override with covariant return type
211 public LocalDate date(int prolepticYear, int month, int dayOfMonth) {
212 return LocalDate.of(prolepticYear, month, dayOfMonth);
213 }
214
215 /**
216 * Obtains an ISO local date from the era, year-of-era and day-of-year fields.
217 *
218 * @param era the ISO era, not null
219 * @param yearOfEra the ISO year-of-era
220 * @param dayOfYear the ISO day-of-year
221 * @return the ISO local date, not null
222 * @throws DateTimeException if unable to create the date
223 */
224 @Override // override with covariant return type
225 public LocalDate dateYearDay(Era era, int yearOfEra, int dayOfYear) {
226 return dateYearDay(prolepticYear(era, yearOfEra), dayOfYear);
227 }
228
229 /**
230 * Obtains an ISO local date from the proleptic-year and day-of-year fields.
231 * <p>
232 * This is equivalent to {@link LocalDate#ofYearDay(int, int)}.
233 *
234 * @param prolepticYear the ISO proleptic-year
235 * @param dayOfYear the ISO day-of-year
236 * @return the ISO local date, not null
237 * @throws DateTimeException if unable to create the date
238 */
239 @Override // override with covariant return type
240 public LocalDate dateYearDay(int prolepticYear, int dayOfYear) {
241 return LocalDate.ofYearDay(prolepticYear, dayOfYear);
242 }
243
244 //-----------------------------------------------------------------------
245 /**
246 * Obtains an ISO local date from another date-time object.
247 * <p>
248 * This is equivalent to {@link LocalDate#from(TemporalAccessor)}.
249 *
250 * @param temporal the date-time object to convert, not null
251 * @return the ISO local date, not null
252 * @throws DateTimeException if unable to create the date
253 */
254 @Override // override with covariant return type
255 public LocalDate date(TemporalAccessor temporal) {
256 return LocalDate.from(temporal);
257 }
258
259 /**
260 * Obtains an ISO local date-time from another date-time object.
261 * <p>
262 * This is equivalent to {@link LocalDateTime#from(TemporalAccessor)}.
263 *
264 * @param temporal the date-time object to convert, not null
265 * @return the ISO local date-time, not null
266 * @throws DateTimeException if unable to create the date-time
267 */
268 @Override // override with covariant return type
269 public LocalDateTime localDateTime(TemporalAccessor temporal) {
270 return LocalDateTime.from(temporal);
271 }
272
273 /**
274 * Obtains an ISO zoned date-time from another date-time object.
275 * <p>
276 * This is equivalent to {@link ZonedDateTime#from(TemporalAccessor)}.
277 *
278 * @param temporal the date-time object to convert, not null
279 * @return the ISO zoned date-time, not null
280 * @throws DateTimeException if unable to create the date-time
281 */
282 @Override // override with covariant return type
283 public ZonedDateTime zonedDateTime(TemporalAccessor temporal) {
284 return ZonedDateTime.from(temporal);
285 }
286
287 /**
288 * Obtains an ISO zoned date-time in this chronology from an {@code Instant}.
289 * <p>
290 * This is equivalent to {@link ZonedDateTime#ofInstant(Instant, ZoneId)}.
291 *
292 * @param instant the instant to create the date-time from, not null
293 * @param zone the time-zone, not null
294 * @return the zoned date-time, not null
295 * @throws DateTimeException if the result exceeds the supported range
296 */
297 @Override
298 public ZonedDateTime zonedDateTime(Instant instant, ZoneId zone) {
299 return ZonedDateTime.ofInstant(instant, zone);
300 }
301
302 //-----------------------------------------------------------------------
303 /**
304 * Obtains the current ISO local date from the system clock in the default time-zone.
305 * <p>
306 * This will query the {@link Clock#systemDefaultZone() system clock} in the default
307 * time-zone to obtain the current date.
308 * <p>
309 * Using this method will prevent the ability to use an alternate clock for testing
310 * because the clock is hard-coded.
311 *
312 * @return the current ISO local date using the system clock and default time-zone, not null
313 * @throws DateTimeException if unable to create the date
314 */
315 @Override // override with covariant return type
316 public LocalDate dateNow() {
317 return dateNow(Clock.systemDefaultZone());
318 }
319
320 /**
321 * Obtains the current ISO local date from the system clock in the specified time-zone.
322 * <p>
323 * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current date.
324 * Specifying the time-zone avoids dependence on the default time-zone.
325 * <p>
326 * Using this method will prevent the ability to use an alternate clock for testing
327 * because the clock is hard-coded.
328 *
329 * @return the current ISO local date using the system clock, not null
330 * @throws DateTimeException if unable to create the date
331 */
332 @Override // override with covariant return type
333 public LocalDate dateNow(ZoneId zone) {
334 return dateNow(Clock.system(zone));
335 }
336
337 /**
338 * Obtains the current ISO local date from the specified clock.
339 * <p>
340 * This will query the specified clock to obtain the current date - today.
341 * Using this method allows the use of an alternate clock for testing.
342 * The alternate clock may be introduced using {@link Clock dependency injection}.
343 *
344 * @param clock the clock to use, not null
345 * @return the current ISO local date, not null
346 * @throws DateTimeException if unable to create the date
347 */
348 @Override // override with covariant return type
349 public LocalDate dateNow(Clock clock) {
350 Objects.requireNonNull(clock, "clock");
351 return date(LocalDate.now(clock));
352 }
353
354 //-----------------------------------------------------------------------
355 /**
356 * Checks if the year is a leap year, according to the ISO proleptic
357 * calendar system rules.
358 * <p>
359 * This method applies the current rules for leap years across the whole time-line.
360 * In general, a year is a leap year if it is divisible by four without
361 * remainder. However, years divisible by 100, are not leap years, with
362 * the exception of years divisible by 400 which are.
363 * <p>
364 * For example, 1904 is a leap year it is divisible by 4.
365 * 1900 was not a leap year as it is divisible by 100, however 2000 was a
366 * leap year as it is divisible by 400.
367 * <p>
368 * The calculation is proleptic - applying the same rules into the far future and far past.
369 * This is historically inaccurate, but is correct for the ISO-8601 standard.
370 *
371 * @param prolepticYear the ISO proleptic year to check
372 * @return true if the year is leap, false otherwise
373 */
374 @Override
375 public boolean isLeapYear(long prolepticYear) {
376 return ((prolepticYear & 3) == 0) && ((prolepticYear % 100) != 0 || (prolepticYear % 400) == 0);
377 }
378
379 @Override
380 public int prolepticYear(Era era, int yearOfEra) {
381 if (era instanceof IsoEra == false) {
382 throw new DateTimeException("Era must be IsoEra");
383 }
384 return (era == IsoEra.CE ? yearOfEra : 1 - yearOfEra);
385 }
386
387 @Override
388 public Era eraOf(int eraValue) {
389 return IsoEra.of(eraValue);
390 }
391
392 @Override
393 public List<Era> eras() {
394 return Arrays.<Era>asList(IsoEra.values());
395 }
396
397 //-----------------------------------------------------------------------
398 @Override
399 public ValueRange range(ChronoField field) {
400 return field.range();
401 }
402
403 }