DateComponents.java

  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;

  19. import java.io.Serializable;
  20. import java.text.DecimalFormat;
  21. import java.util.regex.Matcher;
  22. import java.util.regex.Pattern;

  24. import org.orekit.errors.OrekitIllegalArgumentException;
  25. import org.orekit.errors.OrekitMessages;

  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> {

  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;

  53.     /** Reference epoch for modified julian dates: 1858-11-17. */
  54.     public static final DateComponents MODIFIED_JULIAN_EPOCH;

  56.     /** Reference epoch for 1950 dates: 1950-01-01. */
  57.     public static final DateComponents FIFTIES_EPOCH;

  59.     /** Reference epoch for CCSDS Time Code Format (CCSDS 301.0-B-4): 1958-01-01. */
  60.     public static final DateComponents CCSDS_EPOCH;

  62.     /** Reference epoch for Galileo System Time: 1999-08-22. */
  63.     public static final DateComponents GALILEO_EPOCH;

  65.     /** Reference epoch for GPS weeks: 1980-01-06. */
  66.     public static final DateComponents GPS_EPOCH;

  68.     /** J2000.0 Reference epoch: 2000-01-01. */
  69.     public static final DateComponents J2000_EPOCH;

  71.     /** Java Reference epoch: 1970-01-01. */
  72.     public static final DateComponents JAVA_EPOCH;

  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;

  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;

  92.     /** Serializable UID. */
  93.     private static final long serialVersionUID = -2462694707837970938L;

  95.     /** Factory for proleptic julian calendar (up to 0000-12-31). */
  96.     private static final YearFactory PROLEPTIC_JULIAN_FACTORY = new ProlepticJulianFactory();

  98.     /** Factory for julian calendar (from 0001-01-01 to 1582-10-04). */
  99.     private static final YearFactory JULIAN_FACTORY           = new JulianFactory();

  101.     /** Factory for gregorian calendar (from 1582-10-15). */
  102.     private static final YearFactory GREGORIAN_FACTORY        = new GregorianFactory();

  104.     /** Factory for leap years. */
  105.     private static final MonthDayFactory LEAP_YEAR_FACTORY    = new LeapYearFactory();

  107.     /** Factory for non-leap years. */
  108.     private static final MonthDayFactory COMMON_YEAR_FACTORY  = new CommonYearFactory();

  110.     /** Format for years. */
  111.     private static final DecimalFormat FOUR_DIGITS = new DecimalFormat("0000");

  113.     /** Format for months and days. */
  114.     private static final DecimalFormat TWO_DIGITS  = new DecimalFormat("00");

  116.     /** Offset between J2000 epoch and modified julian day epoch. */
  117.     private static final int MJD_TO_J2000 = 51544;

  119.     /** Basic and extended format calendar date. */
  120.     private static Pattern CALENDAR_FORMAT = Pattern.compile("^(-?\\d\\d\\d\\d)-?(\\d\\d)-?(\\d\\d)$");

  122.     /** Basic and extended format ordinal date. */
  123.     private static Pattern ORDINAL_FORMAT = Pattern.compile("^(-?\\d\\d\\d\\d)-?(\\d\\d\\d)$");

  125.     /** Basic and extended format week date. */
  126.     private static Pattern WEEK_FORMAT = Pattern.compile("^(-?\\d\\d\\d\\d)-?W(\\d\\d)-?(\\d)$");

  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.     }

  143.     /** Year number. */
  144.     private final int year;

  146.     /** Month number. */
  147.     private final int month;

  149.     /** Day number. */
  150.     private final int day;

  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 {

  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.         }

  169.         // start by trusting the parameters
  170.         this.year  = year;
  171.         this.month = month;
  172.         this.day   = day;

  174.         // build a check date from the J2000 day
  175.         final DateComponents check = new DateComponents(getJ2000Day());

  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.         }

  184.     }

  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.     }

  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.     }

  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) {

  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);

  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);

  242.     }

  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.     }

  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 {

  276.         final DateComponents firstWeekMonday = new DateComponents(getFirstWeekMonday(wYear));
  277.         final DateComponents d = new DateComponents(firstWeekMonday, 7 * week + dayOfWeek - 8);

  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.         }

  285.         return d;

  287.     }

  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) {

  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.         }

  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.         }

  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.         }

  338.         throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_DATE, string);

  340.     }

  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.     }

  349.     /** Get the month.
  350.      * @return month number from 1 to 12
  351.      */
  352.     public int getMonth() {
  353.         return month;
  354.     }

  356.     /** Get the month as an enumerate.
  357.      * @return month as an enumerate
  358.      */
  359.     public Month getMonthEnum() {
  360.         return Month.getMonth(month);
  361.     }

  363.     /** Get the day.
  364.      * @return day number from 1 to 31
  365.      */
  366.     public int getDay() {
  367.         return day;
  368.     }

  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.     }

  388.     /** Get the modified julian day.
  389.      * @return modified julian day
  390.      */
  391.     public int getMJD() {
  392.         return MJD_TO_J2000 + getJ2000Day();
  393.     }

  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.     }

  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.     }

  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.     }

  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.     }

  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.     }

  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.     }

  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.     }

  485.     /** {@inheritDoc} */
  486.     public int hashCode() {
  487.         return (year << 16) ^ (month << 8) ^ day;
  488.     }

  490.     /** Interface for dealing with years sequences according to some calendar. */
  491.     private interface YearFactory {

  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);

  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);

  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);

  511.     }

  513.     /** Class providing a years sequence compliant with the proleptic Julian calendar. */
  514.     private static class ProlepticJulianFactory implements YearFactory {

  516.         /** {@inheritDoc} */
  517.         public int getYear(final int j2000Day) {
  518.             return  (int) -((-4l * j2000Day - 2920488l) / 1461l);
  519.         }

  521.         /** {@inheritDoc} */
  522.         public int getLastJ2000DayOfYear(final int year) {
  523.             return 365 * year + (year + 1) / 4 - 730123;
  524.         }

  526.         /** {@inheritDoc} */
  527.         public boolean isLeap(final int year) {
  528.             return (year % 4) == 0;
  529.         }

  531.     }

  533.     /** Class providing a years sequence compliant with the Julian calendar. */
  534.     private static class JulianFactory implements YearFactory {

  536.         /** {@inheritDoc} */
  537.         public int getYear(final int j2000Day) {
  538.             return  (int) ((4l * j2000Day + 2921948l) / 1461l);
  539.         }

  541.         /** {@inheritDoc} */
  542.         public int getLastJ2000DayOfYear(final int year) {
  543.             return 365 * year + year / 4 - 730122;
  544.         }

  546.         /** {@inheritDoc} */
  547.         public boolean isLeap(final int year) {
  548.             return (year % 4) == 0;
  549.         }

  551.     }

  553.     /** Class providing a years sequence compliant with the Gregorian calendar. */
  554.     private static class GregorianFactory implements YearFactory {

  556.         /** {@inheritDoc} */
  557.         public int getYear(final int j2000Day) {

  559.             // year estimate
  560.             int year = (int) ((400l * j2000Day + 292194288l) / 146097l);

  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.             }

  568.             // exact year
  569.             return year;

  571.         }

  573.         /** {@inheritDoc} */
  574.         public int getLastJ2000DayOfYear(final int year) {
  575.             return 365 * year + year / 4 - year / 100 + year / 400 - 730120;
  576.         }

  578.         /** {@inheritDoc} */
  579.         public boolean isLeap(final int year) {
  580.             return ((year % 4) == 0) && (((year % 400) == 0) || ((year % 100) != 0));
  581.         }

  583.     }

  585.     /** Interface for dealing with months sequences according to leap/common years. */
  586.     private interface MonthDayFactory {

  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);

  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);

  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);

  608.     }

  610.     /** Class providing the months sequence for leap years. */
  611.     private static class LeapYearFactory implements MonthDayFactory {

  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.         };

  618.         /** {@inheritDoc} */
  619.         public int getMonth(final int dayInYear) {
  620.             return (dayInYear < 32) ? 1 : (10 * dayInYear + 313) / 306;
  621.         }

  623.         /** {@inheritDoc} */
  624.         public int getDay(final int dayInYear, final int month) {
  625.             return dayInYear - PREVIOUS_MONTH_END_DAY[month];
  626.         }

  628.         /** {@inheritDoc} */
  629.         public int getDayInYear(final int month, final int day) {
  630.             return day + PREVIOUS_MONTH_END_DAY[month];
  631.         }

  633.     }

  635.     /** Class providing the months sequence for common years. */
  636.     private static class CommonYearFactory implements MonthDayFactory {

  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.         };

  643.         /** {@inheritDoc} */
  644.         public int getMonth(final int dayInYear) {
  645.             return (dayInYear < 32) ? 1 : (10 * dayInYear + 323) / 306;
  646.         }

  648.         /** {@inheritDoc} */
  649.         public int getDay(final int dayInYear, final int month) {
  650.             return dayInYear - PREVIOUS_MONTH_END_DAY[month];
  651.         }

  653.         /** {@inheritDoc} */
  654.         public int getDayInYear(final int month, final int day) {
  655.             return day + PREVIOUS_MONTH_END_DAY[month];
  656.         }

  658.     }

  660. }
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