Module java.base
Package java.time.chrono

Class JapaneseChronology

  • All Implemented Interfaces:
    Serializable, Comparable<Chronology>, Chronology
    public final class JapaneseChronology
extends AbstractChronology
implements Serializable
    The Japanese Imperial calendar system.

    This chronology defines the rules of the Japanese Imperial calendar system. This calendar system is primarily used in Japan. The Japanese Imperial calendar system is the same as the ISO calendar system apart from the era-based year numbering.

    Japan introduced the Gregorian calendar starting with Meiji 6. Only Meiji and later eras are supported; dates before Meiji 6, January 1 are not supported.

    The supported ChronoField instances are:

    • DAY_OF_WEEK
    • DAY_OF_MONTH
    • DAY_OF_YEAR
    • EPOCH_DAY
    • MONTH_OF_YEAR
    • PROLEPTIC_MONTH
    • YEAR_OF_ERA
    • YEAR
    • ERA
    Implementation Requirements:
    This class is immutable and thread-safe.
    Since:
    1.8
    See Also:
    Serialized Form

    • Field Detail

      • INSTANCE

        public static final JapaneseChronology INSTANCE
        Singleton instance for Japanese chronology.

    • Method Detail

      • getId

        public String getId()
        Gets the ID of the chronology - 'Japanese'.

        The ID uniquely identifies the Chronology. It can be used to lookup the Chronology using Chronology.of(String).

        Specified by:
        getId in interface Chronology
        Returns:
        the chronology ID - 'Japanese'
        See Also:
        getCalendarType()

      • getCalendarType

        public String getCalendarType()
        Gets the calendar type of the underlying calendar system - 'japanese'.

        The calendar type is an identifier defined by the Unicode Locale Data Markup Language (LDML) specification. It can be used to lookup the Chronology using Chronology.of(String). It can also be used as part of a locale, accessible via Locale.getUnicodeLocaleType(String) with the key 'ca'.

        Specified by:
        getCalendarType in interface Chronology
        Returns:
        the calendar system type - 'japanese'
        See Also:
        getId()

      • date

        public JapaneseDate date​(Era era,
                         int yearOfEra,
                         int month,
                         int dayOfMonth)
        Obtains a local date in Japanese calendar system from the era, year-of-era, month-of-year and day-of-month fields.

        The Japanese month and day-of-month are the same as those in the ISO calendar system. They are not reset when the era changes. For example: 

          6th Jan Showa 64 = ISO 1989-01-06
  7th Jan Showa 64 = ISO 1989-01-07
  8th Jan Heisei 1 = ISO 1989-01-08
  9th Jan Heisei 1 = ISO 1989-01-09
        Specified by:
        date in interface Chronology
        Parameters:
        era - the Japanese era, not null
        yearOfEra - the year-of-era
        month - the month-of-year
        dayOfMonth - the day-of-month
        Returns:
        the Japanese local date, not null
        Throws:
        DateTimeException - if unable to create the date
        ClassCastException - if the era is not a JapaneseEra

      • date

        public JapaneseDate date​(int prolepticYear,
                         int month,
                         int dayOfMonth)
        Obtains a local date in Japanese calendar system from the proleptic-year, month-of-year and day-of-month fields.

        The Japanese proleptic year, month and day-of-month are the same as those in the ISO calendar system. They are not reset when the era changes.

        Specified by:
        date in interface Chronology
        Parameters:
        prolepticYear - the proleptic-year
        month - the month-of-year
        dayOfMonth - the day-of-month
        Returns:
        the Japanese local date, not null
        Throws:
        DateTimeException - if unable to create the date

      • dateYearDay

        public JapaneseDate dateYearDay​(Era era,
                                int yearOfEra,
                                int dayOfYear)
        Obtains a local date in Japanese calendar system from the era, year-of-era and day-of-year fields.

        The day-of-year in this factory is expressed relative to the start of the year-of-era. This definition changes the normal meaning of day-of-year only in those years where the year-of-era is reset to one due to a change in the era. For example: 

          6th Jan Showa 64 = day-of-year 6
  7th Jan Showa 64 = day-of-year 7
  8th Jan Heisei 1 = day-of-year 1
  9th Jan Heisei 1 = day-of-year 2
        Specified by:
        dateYearDay in interface Chronology
        Parameters:
        era - the Japanese era, not null
        yearOfEra - the year-of-era
        dayOfYear - the day-of-year
        Returns:
        the Japanese local date, not null
        Throws:
        DateTimeException - if unable to create the date
        ClassCastException - if the era is not a JapaneseEra

      • dateYearDay

        public JapaneseDate dateYearDay​(int prolepticYear,
                                int dayOfYear)
        Obtains a local date in Japanese calendar system from the proleptic-year and day-of-year fields.

        The day-of-year in this factory is expressed relative to the start of the proleptic year. The Japanese proleptic year and day-of-year are the same as those in the ISO calendar system. They are not reset when the era changes.

        Specified by:
        dateYearDay in interface Chronology
        Parameters:
        prolepticYear - the proleptic-year
        dayOfYear - the day-of-year
        Returns:
        the Japanese local date, not null
        Throws:
        DateTimeException - if unable to create the date

      • dateEpochDay

        public JapaneseDate dateEpochDay​(long epochDay)
        Obtains a local date in the Japanese calendar system from the epoch-day.
        Specified by:
        dateEpochDay in interface Chronology
        Parameters:
        epochDay - the epoch day
        Returns:
        the Japanese local date, not null
        Throws:
        DateTimeException - if unable to create the date

      • isLeapYear

        public boolean isLeapYear​(long prolepticYear)
        Checks if the specified year is a leap year.

        Japanese calendar leap years occur exactly in line with ISO leap years. This method does not validate the year passed in, and only has a well-defined result for years in the supported range.

        Specified by:
        isLeapYear in interface Chronology
        Parameters:
        prolepticYear - the proleptic-year to check, not validated for range
        Returns:
        true if the year is a leap year