Package org.joda.time.chrono

Class IslamicChronology

java.lang.Object
org.joda.time.Chronology
org.joda.time.chrono.BaseChronology
org.joda.time.chrono.AssembledChronology
org.joda.time.chrono.BasicChronology
org.joda.time.chrono.IslamicChronology
All Implemented Interfaces:
Serializable
public final class IslamicChronology extends BasicChronology
Implements the Islamic, or Hijri, calendar system using arithmetic rules.

This calendar is a lunar calendar with a shorter year than ISO. Year 1 in the Islamic calendar began on July 16, 622 CE (Julian), thus Islamic years do not begin at the same time as Julian years. This chronology is not proleptic, as it does not allow dates before the first Islamic year.

There are two basic forms of the Islamic calendar, the tabular and the observed. The observed form cannot easily be used by computers as it relies on human observation of the new moon. The tabular calendar, implemented here, is an arithmetical approximation of the observed form that follows relatively simple rules.

The tabular form of the calendar defines 12 months of alternately 30 and 29 days. The last month is extended to 30 days in a leap year. Leap years occur according to a 30 year cycle. There are four recognised patterns of leap years in the 30 year cycle: 

 Years 2, 5, 7, 10, 13, 15, 18, 21, 24, 26 invalid input: '&' 29 - 15-based, used by Microsoft
 Years 2, 5, 7, 10, 13, 16, 18, 21, 24, 26 invalid input: '&' 29 - 16-based, most commonly used
 Years 2, 5, 8, 10, 13, 16, 19, 21, 24, 27 invalid input: '&' 29 - Indian
 Years 2, 5, 8, 11, 13, 16, 19, 21, 24, 27 invalid input: '&' 30 - Habash al-Hasib
You can select which pattern to use via the factory methods, or use the default (16-based).

This implementation defines a day as midnight to midnight exactly as per the ISO chronology. This correct start of day is at sunset on the previous day, however this cannot readily be modelled and has been ignored.

IslamicChronology is thread-safe and immutable.

Since:
1.2
See Also:

  • Field Details

    • serialVersionUID

      private static final long serialVersionUID
      Serialization lock
      See Also:

    • AH

      public static final int AH
      Constant value for 'Anno Hegirae', equivalent to the value returned for AD/CE.
      See Also:

    • ERA_FIELD

      private static final DateTimeField ERA_FIELD
      A singleton era field.

    • LEAP_YEAR_15_BASED

      public static final IslamicChronology.LeapYearPatternType LEAP_YEAR_15_BASED
      Leap year 15-based pattern.

    • LEAP_YEAR_16_BASED

      public static final IslamicChronology.LeapYearPatternType LEAP_YEAR_16_BASED
      Leap year 16-based pattern.

    • LEAP_YEAR_INDIAN

      public static final IslamicChronology.LeapYearPatternType LEAP_YEAR_INDIAN
      Leap year Indian pattern.

    • LEAP_YEAR_HABASH_AL_HASIB

      public static final IslamicChronology.LeapYearPatternType LEAP_YEAR_HABASH_AL_HASIB
      Leap year Habash al-Hasib pattern.

    • MIN_YEAR

      private static final int MIN_YEAR
      The lowest year that can be fully supported.
      See Also:

    • MAX_YEAR

      private static final int MAX_YEAR
      The highest year that can be fully supported. Although calculateFirstDayOfYearMillis can go higher without overflowing, the getYear method overflows when it adds the approximate millis at the epoch.
      See Also:

    • MONTH_PAIR_LENGTH

      private static final int MONTH_PAIR_LENGTH
      The days in a pair of months.
      See Also:

    • LONG_MONTH_LENGTH

      private static final int LONG_MONTH_LENGTH
      The length of the long month.
      See Also:

    • SHORT_MONTH_LENGTH

      private static final int SHORT_MONTH_LENGTH
      The length of the short month.
      See Also:

    • MILLIS_PER_MONTH_PAIR

      private static final long MILLIS_PER_MONTH_PAIR
      The length of the long month in millis.
      See Also:

    • MILLIS_PER_MONTH

      private static final long MILLIS_PER_MONTH
      The length of the long month in millis.
      See Also:

    • MILLIS_PER_LONG_MONTH

      private static final long MILLIS_PER_LONG_MONTH
      The length of the long month in millis.
      See Also:

    • MILLIS_PER_YEAR

      private static final long MILLIS_PER_YEAR
      The typical millis per year.
      See Also:

    • MILLIS_PER_SHORT_YEAR

      private static final long MILLIS_PER_SHORT_YEAR
      The typical millis per year.
      See Also:

    • MILLIS_PER_LONG_YEAR

      private static final long MILLIS_PER_LONG_YEAR
      The typical millis per year.
      See Also:

    • MILLIS_YEAR_1

      private static final long MILLIS_YEAR_1
      The millis of 0001-01-01.
      See Also:

    • CYCLE

      private static final int CYCLE
      The length of the cycle of leap years.
      See Also:

    • MILLIS_PER_CYCLE

      private static final long MILLIS_PER_CYCLE
      The millis of a 30 year cycle.
      See Also:

    • cCache

      private static final ConcurrentHashMap<DateTimeZone,IslamicChronology[]> cCache
      Cache of zone to chronology arrays

    • INSTANCE_UTC

      private static final IslamicChronology INSTANCE_UTC
      Singleton instance of a UTC IslamicChronology

    • iLeapYears

      private final IslamicChronology.LeapYearPatternType iLeapYears
      The leap years to use.

  • Constructor Details

  • Method Details

    • getInstanceUTC

      public static IslamicChronology getInstanceUTC()
      Gets an instance of the IslamicChronology. The time zone of the returned instance is UTC.
      Returns:
      a singleton UTC instance of the chronology

    • getInstance

      public static IslamicChronology getInstance()
      Gets an instance of the IslamicChronology in the default time zone.
      Returns:
      a chronology in the default time zone

    • getInstance

      public static IslamicChronology getInstance(DateTimeZone zone)
      Gets an instance of the IslamicChronology in the given time zone.
      Parameters:
      zone - the time zone to get the chronology in, null is default
      Returns:
      a chronology in the specified time zone

    • getInstance

      public static IslamicChronology getInstance(DateTimeZone zone, IslamicChronology.LeapYearPatternType leapYears)
      Gets an instance of the IslamicChronology in the given time zone.
      Parameters:
      zone - the time zone to get the chronology in, null is default
      leapYears - the type defining the leap year pattern
      Returns:
      a chronology in the specified time zone

    • readResolve

      private Object readResolve()
      Serialization singleton.

    • getLeapYearPatternType

      public IslamicChronology.LeapYearPatternType getLeapYearPatternType()
      Gets the leap year pattern type.
      Returns:
      the pattern type

    • withUTC

      public Chronology withUTC()
      Gets the Chronology in the UTC time zone.
      Specified by:
      withUTC in class BaseChronology
      Returns:
      the chronology in UTC

    • withZone

      public Chronology withZone(DateTimeZone zone)
      Gets the Chronology in a specific time zone.
      Specified by:
      withZone in class BaseChronology
      Parameters:
      zone - the zone to get the chronology in, null is default
      Returns:
      the chronology
      See Also:

    • equals

      public boolean equals(Object obj)
      Checks if this chronology instance equals another.
      Overrides:
      equals in class BasicChronology
      Parameters:
      obj - the object to compare to
      Returns:
      true if equal
      Since:
      2.3

    • hashCode

      public int hashCode()
      A suitable hash code for the chronology.
      Overrides:
      hashCode in class BasicChronology
      Returns:
      the hash code
      Since:
      1.6

    • getYear

      int getYear(long instant)
      Overrides:
      getYear in class BasicChronology
      Parameters:
      instant - millis from 1970-01-01T00:00:00Z

    • setYear

      long setYear(long instant, int year)
      Description copied from class: BasicChronology
      Sets the year from an instant and year.
      Specified by:
      setYear in class BasicChronology
      Parameters:
      instant - millis from 1970-01-01T00:00:00Z
      year - the year to set
      Returns:
      the updated millis

    • getYearDifference

      long getYearDifference(long minuendInstant, long subtrahendInstant)
      Description copied from class: BasicChronology
      Gets the difference between the two instants in years.
      Specified by:
      getYearDifference in class BasicChronology
      Parameters:
      minuendInstant - the first instant
      subtrahendInstant - the second instant
      Returns:
      the difference

    • getTotalMillisByYearMonth

      long getTotalMillisByYearMonth(int year, int month)
      Description copied from class: BasicChronology
      Gets the total number of millis elapsed in this year at the start of the specified month, such as zero for month 1.
      Specified by:
      getTotalMillisByYearMonth in class BasicChronology
      Parameters:
      year - the year
      month - the month
      Returns:
      the elapsed millis at the start of the month

    • getDayOfMonth

      int getDayOfMonth(long millis)
      Overrides:
      getDayOfMonth in class BasicChronology
      Parameters:
      millis - from 1970-01-01T00:00:00Z

    • isLeapYear

      boolean isLeapYear(int year)
      Description copied from class: BasicChronology
      Is the specified year a leap year?
      Specified by:
      isLeapYear in class BasicChronology
      Parameters:
      year - the year to test
      Returns:
      true if leap

    • getDaysInYearMax

      int getDaysInYearMax()
      Description copied from class: BasicChronology
      Get the number of days in the year.
      Overrides:
      getDaysInYearMax in class BasicChronology
      Returns:
      366

    • getDaysInYear

      int getDaysInYear(int year)
      Description copied from class: BasicChronology
      Get the number of days in the year.
      Overrides:
      getDaysInYear in class BasicChronology
      Parameters:
      year - the year to use
      Returns:
      366 if a leap year, otherwise 365

    • getDaysInYearMonth

      int getDaysInYearMonth(int year, int month)
      Description copied from class: BasicChronology
      Gets the number of days in the specified month and year.
      Specified by:
      getDaysInYearMonth in class BasicChronology
      Parameters:
      year - the year
      month - the month
      Returns:
      the number of days

    • getDaysInMonthMax

      int getDaysInMonthMax()
      Description copied from class: BasicChronology
      Gets the maximum number of days in any month.
      Overrides:
      getDaysInMonthMax in class BasicChronology
      Returns:
      31

    • getDaysInMonthMax

      int getDaysInMonthMax(int month)
      Description copied from class: BasicChronology
      Gets the maximum days in the specified month.
      Specified by:
      getDaysInMonthMax in class BasicChronology
      Parameters:
      month - the month
      Returns:
      the max days

    • getMonthOfYear

      int getMonthOfYear(long millis, int year)
      Specified by:
      getMonthOfYear in class BasicChronology
      Parameters:
      millis - from 1970-01-01T00:00:00Z
      year - precalculated year of millis

    • getAverageMillisPerYear

      long getAverageMillisPerYear()
      Description copied from class: BasicChronology
      Gets an average value for the milliseconds per year.
      Specified by:
      getAverageMillisPerYear in class BasicChronology
      Returns:
      the millis per year

    • getAverageMillisPerYearDividedByTwo

      long getAverageMillisPerYearDividedByTwo()
      Description copied from class: BasicChronology
      Gets an average value for the milliseconds per year, divided by two.
      Specified by:
      getAverageMillisPerYearDividedByTwo in class BasicChronology
      Returns:
      the millis per year divided by two

    • getAverageMillisPerMonth

      long getAverageMillisPerMonth()
      Description copied from class: BasicChronology
      Gets an average value for the milliseconds per month.
      Specified by:
      getAverageMillisPerMonth in class BasicChronology
      Returns:
      the millis per month

    • calculateFirstDayOfYearMillis

      long calculateFirstDayOfYearMillis(int year)
      Description copied from class: BasicChronology
      Gets the millisecond value of the first day of the year.
      Specified by:
      calculateFirstDayOfYearMillis in class BasicChronology
      Returns:
      the milliseconds for the first of the year

    • getMinYear

      int getMinYear()
      Description copied from class: BasicChronology
      Gets the minimum supported year.
      Specified by:
      getMinYear in class BasicChronology
      Returns:
      the year

    • getMaxYear

      int getMaxYear()
      Description copied from class: BasicChronology
      Gets the maximum supported year.
      Specified by:
      getMaxYear in class BasicChronology
      Returns:
      the year

    • getApproxMillisAtEpochDividedByTwo

      long getApproxMillisAtEpochDividedByTwo()
      Description copied from class: BasicChronology
      Returns a constant representing the approximate number of milliseconds elapsed from year 0 of this chronology, divided by two. This constant must be defined as: 
          (yearAtEpoch * averageMillisPerYear + millisOfYearAtEpoch) / 2
      where epoch is 1970-01-01 (Gregorian).
      Specified by:
      getApproxMillisAtEpochDividedByTwo in class BasicChronology

    • assemble

      protected void assemble(AssembledChronology.Fields fields)
      Description copied from class: AssembledChronology
      Invoked by the constructor and after deserialization to allow subclasses to define all of its supported fields. All unset fields default to unsupported instances.
      Overrides:
      assemble in class BasicChronology
      Parameters:
      fields - container of fields