1 /* Copyright 2002-2018 CS Systèmes d'Information
2 * Licensed to CS Systèmes d'Information (CS) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * CS licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.orekit.time;
18
19 import java.io.Serializable;
20 import java.text.DecimalFormat;
21 import java.util.regex.Matcher;
22 import java.util.regex.Pattern;
23
24 import org.orekit.errors.OrekitIllegalArgumentException;
25 import org.orekit.errors.OrekitMessages;
26
27 /** Class representing a date broken up as year, month and day components.
28 * <p>This class uses the astronomical convention for calendars,
29 * which is also the convention used by <code>java.util.Date</code>:
30 * a year zero is present between years -1 and +1, and 10 days are
31 * missing in 1582. The calendar used around these special dates are:</p>
32 * <ul>
33 * <li>up to 0000-12-31 : proleptic julian calendar</li>
34 * <li>from 0001-01-01 to 1582-10-04: julian calendar</li>
35 * <li>from 1582-10-15: gregorian calendar</li>
36 * </ul>
37 * <p>Instances of this class are guaranteed to be immutable.</p>
38 * @see TimeComponents
39 * @see DateTimeComponents
40 * @author Luc Maisonobe
41 */
42 public class DateComponents implements Serializable, Comparable<DateComponents> {
43
44 /** Reference epoch for julian dates: -4712-01-01.
45 * <p>Both <code>java.util.Date</code> and {@link DateComponents} classes
46 * follow the astronomical conventions and consider a year 0 between
47 * years -1 and +1, hence this reference date lies in year -4712 and not
48 * in year -4713 as can be seen in other documents or programs that obey
49 * a different convention (for example the <code>convcal</code> utility).</p>
50 */
51 public static final DateComponents JULIAN_EPOCH;
52
53 /** Reference epoch for modified julian dates: 1858-11-17. */
54 public static final DateComponents MODIFIED_JULIAN_EPOCH;
55
56 /** Reference epoch for 1950 dates: 1950-01-01. */
57 public static final DateComponents FIFTIES_EPOCH;
58
59 /** Reference epoch for CCSDS Time Code Format (CCSDS 301.0-B-4): 1958-01-01. */
60 public static final DateComponents CCSDS_EPOCH;
61
62 /** Reference epoch for Galileo System Time: 1999-08-22. */
63 public static final DateComponents GALILEO_EPOCH;
64
65 /** Reference epoch for GPS weeks: 1980-01-06. */
66 public static final DateComponents GPS_EPOCH;
67
68 /** J2000.0 Reference epoch: 2000-01-01. */
69 public static final DateComponents J2000_EPOCH;
70
71 /** Java Reference epoch: 1970-01-01. */
72 public static final DateComponents JAVA_EPOCH;
73
74 /** Maximum supported date.
75 * <p>
76 * This is date 5881610-07-11 which corresponds to {@code Integer.MAX_VALUE}
77 * days after {@link #J2000_EPOCH}.
78 * </p>
79 * @since 9.0
80 */
81 public static final DateComponents MAX_EPOCH;
82
83 /** Maximum supported date.
84 * <p>
85 * This is date -5877490-03-03, which corresponds to {@code Integer.MIN_VALUE}
86 * days before {@link #J2000_EPOCH}.
87 * </p>
88 * @since 9.0
89 */
90 public static final DateComponents MIN_EPOCH;
91
92 /** Serializable UID. */
93 private static final long serialVersionUID = -2462694707837970938L;
94
95 /** Factory for proleptic julian calendar (up to 0000-12-31). */
96 private static final YearFactory PROLEPTIC_JULIAN_FACTORY = new ProlepticJulianFactory();
97
98 /** Factory for julian calendar (from 0001-01-01 to 1582-10-04). */
99 private static final YearFactory JULIAN_FACTORY = new JulianFactory();
100
101 /** Factory for gregorian calendar (from 1582-10-15). */
102 private static final YearFactory GREGORIAN_FACTORY = new GregorianFactory();
103
104 /** Factory for leap years. */
105 private static final MonthDayFactory LEAP_YEAR_FACTORY = new LeapYearFactory();
106
107 /** Factory for non-leap years. */
108 private static final MonthDayFactory COMMON_YEAR_FACTORY = new CommonYearFactory();
109
110 /** Format for years. */
111 private static final DecimalFormat FOUR_DIGITS = new DecimalFormat("0000");
112
113 /** Format for months and days. */
114 private static final DecimalFormat TWO_DIGITS = new DecimalFormat("00");
115
116 /** Offset between J2000 epoch and modified julian day epoch. */
117 private static final int MJD_TO_J2000 = 51544;
118
119 /** Basic and extended format calendar date. */
120 private static Pattern CALENDAR_FORMAT = Pattern.compile("^(-?\\d\\d\\d\\d)-?(\\d\\d)-?(\\d\\d)$");
121
122 /** Basic and extended format ordinal date. */
123 private static Pattern ORDINAL_FORMAT = Pattern.compile("^(-?\\d\\d\\d\\d)-?(\\d\\d\\d)$");
124
125 /** Basic and extended format week date. */
126 private static Pattern WEEK_FORMAT = Pattern.compile("^(-?\\d\\d\\d\\d)-?W(\\d\\d)-?(\\d)$");
127
128 static {
129 // this static statement makes sure the reference epoch are initialized
130 // once AFTER the various factories have been set up
131 JULIAN_EPOCH = new DateComponents(-4712, 1, 1);
132 MODIFIED_JULIAN_EPOCH = new DateComponents(1858, 11, 17);
133 FIFTIES_EPOCH = new DateComponents(1950, 1, 1);
134 CCSDS_EPOCH = new DateComponents(1958, 1, 1);
135 GALILEO_EPOCH = new DateComponents(1999, 8, 22);
136 GPS_EPOCH = new DateComponents(1980, 1, 6);
137 J2000_EPOCH = new DateComponents(2000, 1, 1);
138 JAVA_EPOCH = new DateComponents(1970, 1, 1);
139 MAX_EPOCH = new DateComponents(Integer.MAX_VALUE);
140 MIN_EPOCH = new DateComponents(Integer.MIN_VALUE);
141 }
142
143 /** Year number. */
144 private final int year;
145
146 /** Month number. */
147 private final int month;
148
149 /** Day number. */
150 private final int day;
151
152 /** Build a date from its components.
153 * @param year year number (may be 0 or negative for BC years)
154 * @param month month number from 1 to 12
155 * @param day day number from 1 to 31
156 * @exception IllegalArgumentException if inconsistent arguments
157 * are given (parameters out of range, february 29 for non-leap years,
158 * dates during the gregorian leap in 1582 ...)
159 */
160 public DateComponents(final int year, final int month, final int day)
161 throws IllegalArgumentException {
162
163 // very rough range check
164 // (just to avoid ArrayOutOfboundException in MonthDayFactory later)
165 if ((month < 1) || (month > 12)) {
166 throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_MONTH, month);
167 }
168
169 // start by trusting the parameters
170 this.year = year;
171 this.month = month;
172 this.day = day;
173
174 // build a check date from the J2000 day
175 final DateComponents check = new DateComponents(getJ2000Day());
176
177 // check the parameters for mismatch
178 // (i.e. invalid date components, like 29 february on non-leap years)
179 if ((year != check.year) || (month != check.month) || (day != check.day)) {
180 throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_YEAR_MONTH_DAY,
181 year, month, day);
182 }
183
184 }
185
186 /** Build a date from its components.
187 * @param year year number (may be 0 or negative for BC years)
188 * @param month month enumerate
189 * @param day day number from 1 to 31
190 * @exception IllegalArgumentException if inconsistent arguments
191 * are given (parameters out of range, february 29 for non-leap years,
192 * dates during the gregorian leap in 1582 ...)
193 */
194 public DateComponents(final int year, final Month month, final int day)
195 throws IllegalArgumentException {
196 this(year, month.getNumber(), day);
197 }
198
199 /** Build a date from a year and day number.
200 * @param year year number (may be 0 or negative for BC years)
201 * @param dayNumber day number in the year from 1 to 366
202 * @exception IllegalArgumentException if dayNumber is out of range
203 * with respect to year
204 */
205 public DateComponents(final int year, final int dayNumber)
206 throws IllegalArgumentException {
207 this(J2000_EPOCH, new DateComponents(year - 1, 12, 31).getJ2000Day() + dayNumber);
208 if (dayNumber != getDayOfYear()) {
209 throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_DAY_NUMBER_IN_YEAR,
210 dayNumber, year);
211 }
212 }
213
214 /** Build a date from its offset with respect to a {@link #J2000_EPOCH}.
215 * @param offset offset with respect to a {@link #J2000_EPOCH}
216 * @see #getJ2000Day()
217 */
218 public DateComponents(final int offset) {
219
220 // we follow the astronomical convention for calendars:
221 // we consider a year zero and 10 days are missing in 1582
222 // from 1582-10-15: gregorian calendar
223 // from 0001-01-01 to 1582-10-04: julian calendar
224 // up to 0000-12-31 : proleptic julian calendar
225 YearFactory yFactory = GREGORIAN_FACTORY;
226 if (offset < -152384) {
227 if (offset > -730122) {
228 yFactory = JULIAN_FACTORY;
229 } else {
230 yFactory = PROLEPTIC_JULIAN_FACTORY;
231 }
232 }
233 year = yFactory.getYear(offset);
234 final int dayInYear = offset - yFactory.getLastJ2000DayOfYear(year - 1);
235
236 // handle month/day according to the year being a common or leap year
237 final MonthDayFactory mdFactory =
238 yFactory.isLeap(year) ? LEAP_YEAR_FACTORY : COMMON_YEAR_FACTORY;
239 month = mdFactory.getMonth(dayInYear);
240 day = mdFactory.getDay(dayInYear, month);
241
242 }
243
244 /** Build a date from its offset with respect to a reference epoch.
245 * <p>This constructor is mainly useful to build a date from a modified
246 * julian day (using {@link #MODIFIED_JULIAN_EPOCH}) or a GPS week number
247 * (using {@link #GPS_EPOCH}).</p>
248 * @param epoch reference epoch
249 * @param offset offset with respect to a reference epoch
250 * @see #DateComponents(int)
251 * @see #getMJD()
252 */
253 public DateComponents(final DateComponents epoch, final int offset) {
254 this(epoch.getJ2000Day() + offset);
255 }
256
257 /** Build a date from week components.
258 * <p>The calendar week number is a number between 1 and 52 or 53 depending
259 * on the year. Week 1 is defined by ISO as the one that includes the first
260 * Thursday of a year. Week 1 may therefore start the previous year and week
261 * 52 or 53 may end in the next year. As an example calendar date 1995-01-01
262 * corresponds to week date 1994-W52-7 (i.e. Sunday in the last week of 1994
263 * is in fact the first day of year 1995). This date would beAnother example is calendar date
264 * 1996-12-31 which corresponds to week date 1997-W01-2 (i.e. Tuesday in the
265 * first week of 1997 is in fact the last day of year 1996).</p>
266 * @param wYear year associated to week numbering
267 * @param week week number in year, from 1 to 52 or 53
268 * @param dayOfWeek day of week, from 1 (Monday) to 7 (Sunday)
269 * @return a builded date
270 * @exception IllegalArgumentException if inconsistent arguments
271 * are given (parameters out of range, week 53 on a 52 weeks year ...)
272 */
273 public static DateComponents createFromWeekComponents(final int wYear, final int week, final int dayOfWeek)
274 throws IllegalArgumentException {
275
276 final DateComponents firstWeekMonday = new DateComponents(getFirstWeekMonday(wYear));
277 final DateComponents d = new DateComponents(firstWeekMonday, 7 * week + dayOfWeek - 8);
278
279 // check the parameters for invalid date components
280 if ((week != d.getCalendarWeek()) || (dayOfWeek != d.getDayOfWeek())) {
281 throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_WEEK_DATE,
282 wYear, week, dayOfWeek);
283 }
284
285 return d;
286
287 }
288
289 /** Parse a string in ISO-8601 format to build a date.
290 * <p>The supported formats are:
291 * <ul>
292 * <li>basic format calendar date: YYYYMMDD</li>
293 * <li>extended format calendar date: YYYY-MM-DD</li>
294 * <li>basic format ordinal date: YYYYDDD</li>
295 * <li>extended format ordinal date: YYYY-DDD</li>
296 * <li>basic format week date: YYYYWwwD</li>
297 * <li>extended format week date: YYYY-Www-D</li>
298 * </ul>
299 *
300 * <p> As shown by the list above, only the complete representations defined in section 4.1
301 * of ISO-8601 standard are supported, neither expended representations nor representations
302 * with reduced accuracy are supported.
303 *
304 * <p>
305 * Parsing a single integer as a julian day is <em>not</em> supported as it may be ambiguous
306 * with either the basic format calendar date or the basic format ordinal date depending
307 * on the number of digits.
308 * </p>
309 * @param string string to parse
310 * @return a parsed date
311 * @exception IllegalArgumentException if string cannot be parsed
312 */
313 public static DateComponents parseDate(final String string) {
314
315 // is the date a calendar date ?
316 final Matcher calendarMatcher = CALENDAR_FORMAT.matcher(string);
317 if (calendarMatcher.matches()) {
318 return new DateComponents(Integer.parseInt(calendarMatcher.group(1)),
319 Integer.parseInt(calendarMatcher.group(2)),
320 Integer.parseInt(calendarMatcher.group(3)));
321 }
322
323 // is the date an ordinal date ?
324 final Matcher ordinalMatcher = ORDINAL_FORMAT.matcher(string);
325 if (ordinalMatcher.matches()) {
326 return new DateComponents(Integer.parseInt(ordinalMatcher.group(1)),
327 Integer.parseInt(ordinalMatcher.group(2)));
328 }
329
330 // is the date a week date ?
331 final Matcher weekMatcher = WEEK_FORMAT.matcher(string);
332 if (weekMatcher.matches()) {
333 return createFromWeekComponents(Integer.parseInt(weekMatcher.group(1)),
334 Integer.parseInt(weekMatcher.group(2)),
335 Integer.parseInt(weekMatcher.group(3)));
336 }
337
338 throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_DATE, string);
339
340 }
341
342 /** Get the year number.
343 * @return year number (may be 0 or negative for BC years)
344 */
345 public int getYear() {
346 return year;
347 }
348
349 /** Get the month.
350 * @return month number from 1 to 12
351 */
352 public int getMonth() {
353 return month;
354 }
355
356 /** Get the month as an enumerate.
357 * @return month as an enumerate
358 */
359 public Month getMonthEnum() {
360 return Month.getMonth(month);
361 }
362
363 /** Get the day.
364 * @return day number from 1 to 31
365 */
366 public int getDay() {
367 return day;
368 }
369
370 /** Get the day number with respect to J2000 epoch.
371 * @return day number with respect to J2000 epoch
372 */
373 public int getJ2000Day() {
374 YearFactory yFactory = GREGORIAN_FACTORY;
375 if (year < 1583) {
376 if (year < 1) {
377 yFactory = PROLEPTIC_JULIAN_FACTORY;
378 } else if ((year < 1582) || (month < 10) || ((month < 11) && (day < 5))) {
379 yFactory = JULIAN_FACTORY;
380 }
381 }
382 final MonthDayFactory mdFactory =
383 yFactory.isLeap(year) ? LEAP_YEAR_FACTORY : COMMON_YEAR_FACTORY;
384 return yFactory.getLastJ2000DayOfYear(year - 1) +
385 mdFactory.getDayInYear(month, day);
386 }
387
388 /** Get the modified julian day.
389 * @return modified julian day
390 */
391 public int getMJD() {
392 return MJD_TO_J2000 + getJ2000Day();
393 }
394
395 /** Get the calendar week number.
396 * <p>The calendar week number is a number between 1 and 52 or 53 depending
397 * on the year. Week 1 is defined by ISO as the one that includes the first
398 * Thursday of a year. Week 1 may therefore start the previous year and week
399 * 52 or 53 may end in the next year. As an example calendar date 1995-01-01
400 * corresponds to week date 1994-W52-7 (i.e. Sunday in the last week of 1994
401 * is in fact the first day of year 1995). Another example is calendar date
402 * 1996-12-31 which corresponds to week date 1997-W01-2 (i.e. Tuesday in the
403 * first week of 1997 is in fact the last day of year 1996).</p>
404 * @return calendar week number
405 */
406 public int getCalendarWeek() {
407 final int firstWeekMonday = getFirstWeekMonday(year);
408 int daysSincefirstMonday = getJ2000Day() - firstWeekMonday;
409 if (daysSincefirstMonday < 0) {
410 // we are still in a week from previous year
411 daysSincefirstMonday += firstWeekMonday - getFirstWeekMonday(year - 1);
412 } else if (daysSincefirstMonday > 363) {
413 // up to three days at end of year may belong to first week of next year
414 // (by chance, there is no need for a specific check in year 1582 ...)
415 final int weekYearLength = getFirstWeekMonday(year + 1) - firstWeekMonday;
416 if (daysSincefirstMonday >= weekYearLength) {
417 daysSincefirstMonday -= weekYearLength;
418 }
419 }
420 return 1 + daysSincefirstMonday / 7;
421 }
422
423 /** Get the monday of a year first week.
424 * @param year year to consider
425 * @return day of the monday of the first weak of year
426 */
427 private static int getFirstWeekMonday(final int year) {
428 final int yearFirst = new DateComponents(year, 1, 1).getJ2000Day();
429 final int offsetToMonday = 4 - (yearFirst + 2) % 7;
430 return yearFirst + offsetToMonday + ((offsetToMonday > 3) ? -7 : 0);
431 }
432
433 /** Get the day of week.
434 * <p>Day of week is a number between 1 (Monday) and 7 (Sunday).</p>
435 * @return day of week
436 */
437 public int getDayOfWeek() {
438 final int dow = (getJ2000Day() + 6) % 7; // result is between -6 and +6
439 return (dow < 1) ? (dow + 7) : dow;
440 }
441
442 /** Get the day number in year.
443 * <p>Day number in year is between 1 (January 1st) and either 365 or
444 * 366 inclusive depending on year.</p>
445 * @return day number in year
446 */
447 public int getDayOfYear() {
448 return getJ2000Day() - new DateComponents(year - 1, 12, 31).getJ2000Day();
449 }
450
451 /** Get a string representation (ISO-8601) of the date.
452 * @return string representation of the date.
453 */
454 public String toString() {
455 return new StringBuffer().
456 append(FOUR_DIGITS.format(year)).append('-').
457 append(TWO_DIGITS.format(month)).append('-').
458 append(TWO_DIGITS.format(day)).
459 toString();
460 }
461
462 /** {@inheritDoc} */
463 public int compareTo(final DateComponents other) {
464 final int j2000Day = getJ2000Day();
465 final int otherJ2000Day = other.getJ2000Day();
466 if (j2000Day < otherJ2000Day) {
467 return -1;
468 } else if (j2000Day > otherJ2000Day) {
469 return 1;
470 }
471 return 0;
472 }
473
474 /** {@inheritDoc} */
475 public boolean equals(final Object other) {
476 try {
477 final DateComponents otherDate = (DateComponents) other;
478 return (otherDate != null) && (year == otherDate.year) &&
479 (month == otherDate.month) && (day == otherDate.day);
480 } catch (ClassCastException cce) {
481 return false;
482 }
483 }
484
485 /** {@inheritDoc} */
486 public int hashCode() {
487 return (year << 16) ^ (month << 8) ^ day;
488 }
489
490 /** Interface for dealing with years sequences according to some calendar. */
491 private interface YearFactory {
492
493 /** Get the year number for a given day number with respect to J2000 epoch.
494 * @param j2000Day day number with respect to J2000 epoch
495 * @return year number
496 */
497 int getYear(int j2000Day);
498
499 /** Get the day number with respect to J2000 epoch for new year's Eve.
500 * @param year year number
501 * @return day number with respect to J2000 epoch for new year's Eve
502 */
503 int getLastJ2000DayOfYear(int year);
504
505 /** Check if a year is a leap or common year.
506 * @param year year number
507 * @return true if year is a leap year
508 */
509 boolean isLeap(int year);
510
511 }
512
513 /** Class providing a years sequence compliant with the proleptic Julian calendar. */
514 private static class ProlepticJulianFactory implements YearFactory {
515
516 /** {@inheritDoc} */
517 public int getYear(final int j2000Day) {
518 return (int) -((-4l * j2000Day - 2920488l) / 1461l);
519 }
520
521 /** {@inheritDoc} */
522 public int getLastJ2000DayOfYear(final int year) {
523 return 365 * year + (year + 1) / 4 - 730123;
524 }
525
526 /** {@inheritDoc} */
527 public boolean isLeap(final int year) {
528 return (year % 4) == 0;
529 }
530
531 }
532
533 /** Class providing a years sequence compliant with the Julian calendar. */
534 private static class JulianFactory implements YearFactory {
535
536 /** {@inheritDoc} */
537 public int getYear(final int j2000Day) {
538 return (int) ((4l * j2000Day + 2921948l) / 1461l);
539 }
540
541 /** {@inheritDoc} */
542 public int getLastJ2000DayOfYear(final int year) {
543 return 365 * year + year / 4 - 730122;
544 }
545
546 /** {@inheritDoc} */
547 public boolean isLeap(final int year) {
548 return (year % 4) == 0;
549 }
550
551 }
552
553 /** Class providing a years sequence compliant with the Gregorian calendar. */
554 private static class GregorianFactory implements YearFactory {
555
556 /** {@inheritDoc} */
557 public int getYear(final int j2000Day) {
558
559 // year estimate
560 int year = (int) ((400l * j2000Day + 292194288l) / 146097l);
561
562 // the previous estimate is one unit too high in some rare cases
563 // (240 days in the 400 years gregorian cycle, about 0.16%)
564 if (j2000Day <= getLastJ2000DayOfYear(year - 1)) {
565 --year;
566 }
567
568 // exact year
569 return year;
570
571 }
572
573 /** {@inheritDoc} */
574 public int getLastJ2000DayOfYear(final int year) {
575 return 365 * year + year / 4 - year / 100 + year / 400 - 730120;
576 }
577
578 /** {@inheritDoc} */
579 public boolean isLeap(final int year) {
580 return ((year % 4) == 0) && (((year % 400) == 0) || ((year % 100) != 0));
581 }
582
583 }
584
585 /** Interface for dealing with months sequences according to leap/common years. */
586 private interface MonthDayFactory {
587
588 /** Get the month number for a given day number within year.
589 * @param dayInYear day number within year
590 * @return month number
591 */
592 int getMonth(int dayInYear);
593
594 /** Get the day number for given month and day number within year.
595 * @param dayInYear day number within year
596 * @param month month number
597 * @return day number
598 */
599 int getDay(int dayInYear, int month);
600
601 /** Get the day number within year for given month and day numbers.
602 * @param month month number
603 * @param day day number
604 * @return day number within year
605 */
606 int getDayInYear(int month, int day);
607
608 }
609
610 /** Class providing the months sequence for leap years. */
611 private static class LeapYearFactory implements MonthDayFactory {
612
613 /** Months succession definition. */
614 private static final int[] PREVIOUS_MONTH_END_DAY = {
615 0, 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335
616 };
617
618 /** {@inheritDoc} */
619 public int getMonth(final int dayInYear) {
620 return (dayInYear < 32) ? 1 : (10 * dayInYear + 313) / 306;
621 }
622
623 /** {@inheritDoc} */
624 public int getDay(final int dayInYear, final int month) {
625 return dayInYear - PREVIOUS_MONTH_END_DAY[month];
626 }
627
628 /** {@inheritDoc} */
629 public int getDayInYear(final int month, final int day) {
630 return day + PREVIOUS_MONTH_END_DAY[month];
631 }
632
633 }
634
635 /** Class providing the months sequence for common years. */
636 private static class CommonYearFactory implements MonthDayFactory {
637
638 /** Months succession definition. */
639 private static final int[] PREVIOUS_MONTH_END_DAY = {
640 0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
641 };
642
643 /** {@inheritDoc} */
644 public int getMonth(final int dayInYear) {
645 return (dayInYear < 32) ? 1 : (10 * dayInYear + 323) / 306;
646 }
647
648 /** {@inheritDoc} */
649 public int getDay(final int dayInYear, final int month) {
650 return dayInYear - PREVIOUS_MONTH_END_DAY[month];
651 }
652
653 /** {@inheritDoc} */
654 public int getDayInYear(final int month, final int day) {
655 return day + PREVIOUS_MONTH_END_DAY[month];
656 }
657
658 }
659
660 }