Class JapaneseCalendar

java.lang.Object
com.ibm.icu.util.Calendar
com.ibm.icu.util.GregorianCalendar
com.ibm.icu.util.JapaneseCalendar
All Implemented Interfaces:
Serializable, Cloneable, Comparable<Calendar>
public class JapaneseCalendar extends GregorianCalendar
JapaneseCalendar is a subclass of GregorianCalendar that numbers years and eras based on the reigns of the Japanese emperors. The Japanese calendar is identical to the Gregorian calendar in all respects except for the year and era. The ascension of each emperor to the throne begins a new era, and the years of that era are numbered starting with the year of ascension as year 1.

Note that in the year of an imperial ascension, there are two possible sets of year and era values: that for the old era and for the new. For example, a new era began on January 7, 1989 AD. Strictly speaking, the first six days of that year were in the Showa era, e.g. "January 6, 64 Showa", while the rest of the year was in the Heisei era, e.g. "January 7, 1 Heisei". This class handles this distinction correctly when computing dates. However, in lenient mode either form of date is acceptable as input.

In modern times, eras have started on January 8, 1868 AD, Gregorian (Meiji), July 30, 1912 (Taisho), December 25, 1926 (Showa), and January 7, 1989 (Heisei). Constants for these eras, suitable for use in the ERA field, are provided in this class. Note that the number used for each era is more or less arbitrary. Currently, the era starting in 645 AD is era #0; however this may change in the future. Use the predefined constants rather than using actual, absolute numbers.

Since ICU4J 63, start date of each era is imported from CLDR. CLDR era data may contain tentative era in near future with placeholder names. By default, such era data is not enabled. ICU4J users who want to test the behavior of the future era can enable this by one of following settings (in the priority order):

  1. Java system property ICU_ENABLE_TENTATIVE_ERA=true.
  2. Environment variable ICU_ENABLE_TENTATIVE_ERA=true.
  3. Java system property jdk.calendar.japanese.supplemental.era=xxx. (Note: This configuration is used for specifying a new era's start date and names in OpenJDK. ICU4J implementation enables the CLDR tentative era when this property is defined, but it does not use the start date and names specified by the property value.)

This class should not be subclassed.

JapaneseCalendar usually should be instantiated using Calendar.getInstance(ULocale) passing in a ULocale with the tag "@calendar=japanese".

Author:
Laura Werner, Alan Liu
See Also:
Status:
Stable ICU 2.8.

  • Field Details

    • CURRENT_ERA

      public static final int CURRENT_ERA
      Status:
      Stable ICU 2.8.

    • MEIJI

      public static final int MEIJI
      Constant for the era starting on Sept. 8, 1868 AD.
      Status:
      Stable ICU 2.8.

    • TAISHO

      public static final int TAISHO
      Constant for the era starting on July 30, 1912 AD.
      Status:
      Stable ICU 2.8.

    • SHOWA

      public static final int SHOWA
      Constant for the era starting on Dec. 25, 1926 AD.
      Status:
      Stable ICU 2.8.

    • HEISEI

      public static final int HEISEI
      Constant for the era starting on Jan. 7, 1989 AD.
      Status:
      Stable ICU 2.8.

    • REIWA

      public static final int REIWA
      Constant for the era starting on May 1, 2019 AD.
      Status:
      Stable ICU 64.

  • Constructor Details

    • JapaneseCalendar

      public JapaneseCalendar()
      Constructs a default JapaneseCalendar using the current time in the default time zone with the default locale.
      Status:
      Stable ICU 2.8.

    • JapaneseCalendar

      public JapaneseCalendar(TimeZone zone)
      Constructs a JapaneseCalendar based on the current time in the given time zone with the default locale.
      Parameters:
      zone - the given time zone.
      Status:
      Stable ICU 2.8.

    • JapaneseCalendar

      public JapaneseCalendar(Locale aLocale)
      Constructs a JapaneseCalendar based on the current time in the default time zone with the given locale.
      Parameters:
      aLocale - the given locale.
      Status:
      Stable ICU 2.8.

    • JapaneseCalendar

      public JapaneseCalendar(ULocale locale)
      Constructs a JapaneseCalendar based on the current time in the default time zone with the given locale.
      Parameters:
      locale - the given ulocale.
      Status:
      Stable ICU 3.2.

    • JapaneseCalendar

      public JapaneseCalendar(TimeZone zone, Locale aLocale)
      Constructs a JapaneseCalendar based on the current time in the given time zone with the given locale.
      Parameters:
      zone - the given time zone.
      aLocale - the given locale.
      Status:
      Stable ICU 2.8.

    • JapaneseCalendar

      public JapaneseCalendar(TimeZone zone, ULocale locale)
      Constructs a JapaneseCalendar based on the current time in the given time zone with the given locale.
      Parameters:
      zone - the given time zone.
      locale - the given ulocale.
      Status:
      Stable ICU 3.2.

    • JapaneseCalendar

      public JapaneseCalendar(Date date)
      Constructs a JapaneseCalendar with the given date set in the default time zone with the default locale.
      Parameters:
      date - The date to which the new calendar is set.
      Status:
      Stable ICU 2.8.

    • JapaneseCalendar

      public JapaneseCalendar(int era, int year, int month, int date)
      Constructs a JapaneseCalendar with the given date set in the default time zone with the default locale.
      Parameters:
      era - The imperial era used to set the calendar's ERA field. Eras are numbered starting with the Tenki era, which began in 1053 AD Gregorian, as era zero. Recent eras can be specified using the constants MEIJI (which started in 1868 AD), TAISHO (1912 AD), SHOWA (1926 AD), and HEISEI (1989 AD).
      year - The value used to set the calendar's YEAR field, in terms of the era.
      month - The value used to set the calendar's MONTH field. The value is 0-based. e.g., 0 for January.
      date - The value used to set the calendar's DATE field.
      Status:
      Stable ICU 2.8.

    • JapaneseCalendar

      public JapaneseCalendar(int year, int month, int date)
      Constructs a JapaneseCalendar with the given date set in the default time zone with the default locale.
      Parameters:
      year - The value used to set the calendar's YEAR field, in the era Heisei, the most current at the time this class was last updated.
      month - The value used to set the calendar's MONTH field. The value is 0-based. e.g., 0 for January.
      date - The value used to set the calendar's DATE field.
      Status:
      Stable ICU 2.8.

    • JapaneseCalendar

      public JapaneseCalendar(int year, int month, int date, int hour, int minute, int second)
      Constructs a JapaneseCalendar with the given date and time set for the default time zone with the default locale.
      Parameters:
      year - The value used to set the calendar's YEAR time field, in the era Heisei, the most current at the time of this writing.
      month - The value used to set the calendar's MONTH time field. The value is 0-based. e.g., 0 for January.
      date - The value used to set the calendar's DATE time field.
      hour - The value used to set the calendar's HOUR_OF_DAY time field.
      minute - The value used to set the calendar's MINUTE time field.
      second - The value used to set the calendar's SECOND time field.
      Status:
      Stable ICU 2.8.

  • Method Details

    • enableTentativeEra

      @Deprecated public static boolean enableTentativeEra()
      Deprecated.
      This API is ICU internal only.
      Check environment variable that enables use of future eras.
      Status:
      Internal. This API is ICU internal only.

    • handleGetExtendedYear

      protected int handleGetExtendedYear()
      Description copied from class: Calendar
      Returns the extended year defined by the current fields. This will use the EXTENDED_YEAR field or the YEAR and supra-year fields (such as ERA) specific to the calendar system, depending on which set of fields is newer.
      Overrides:
      handleGetExtendedYear in class GregorianCalendar
      Returns:
      the extended year
      Status:
      Stable ICU 2.8.

    • getDefaultMonthInYear

      protected int getDefaultMonthInYear(int extendedYear)
      Called by handleComputeJulianDay. Returns the default month (0-based) for the year, taking year and era into account. Defaults to 0 (JANUARY) for Gregorian.
      Overrides:
      getDefaultMonthInYear in class Calendar
      Parameters:
      extendedYear - the extendedYear, as returned by handleGetExtendedYear
      Returns:
      the default month
      See Also:
      Status:
      Draft ICU 3.6 (retain).

    • getDefaultDayInMonth

      protected int getDefaultDayInMonth(int extendedYear, int month)
      Called by handleComputeJulianDay. Returns the default day (1-based) for the month, taking currently-set year and era into account. Defaults to 1 for Gregorian.
      Overrides:
      getDefaultDayInMonth in class Calendar
      Parameters:
      extendedYear - the extendedYear, as returned by handleGetExtendedYear
      month - the month, as returned by getDefaultMonthInYear
      Returns:
      the default day of the month
      See Also:
      Status:
      Draft ICU 3.6 (retain).

    • handleComputeFields

      protected void handleComputeFields(int julianDay)
      Description copied from class: GregorianCalendar
      Override Calendar to compute several fields specific to the hybrid Gregorian-Julian calendar system. These are:
      • ERA
      • YEAR
      • MONTH
      • DAY_OF_MONTH
      • DAY_OF_YEAR
      • EXTENDED_YEAR
      Overrides:
      handleComputeFields in class GregorianCalendar
      Status:
      Stable ICU 2.8.

    • handleGetLimit

      protected int handleGetLimit(int field, int limitType)
      Override GregorianCalendar. We should really handle YEAR_WOY and EXTENDED_YEAR here too to implement the 1..5000000 range, but it's not critical.
      Overrides:
      handleGetLimit in class GregorianCalendar
      Parameters:
      field - one of the above field numbers
      limitType - one of MINIMUM, GREATEST_MINIMUM, LEAST_MAXIMUM, or MAXIMUM
      Status:
      Stable ICU 2.8.

    • getType

      public String getType()
      [icu] Returns the calendar type name string for this Calendar object. The returned string is the legacy ICU calendar attribute value, for example, "gregorian" or "japanese".

      See type="old type name" for the calendar attribute of locale IDs at http://www.unicode.org/reports/tr35/#Key_Type_Definitions

      Overrides:
      getType in class GregorianCalendar
      Returns:
      legacy calendar type name string
      Status:
      Stable ICU 3.8.

    • haveDefaultCentury

      @Deprecated public boolean haveDefaultCentury()
      Deprecated.
      This API is ICU internal only.
      Returns if two digit representation of year in this calendar type customarily implies a default century (i.e. 03 -> 2003). The default implementation returns true. A subclass may return false if such practice is not applicable (for example, Chinese calendar and Japanese calendar).
      Overrides:
      haveDefaultCentury in class Calendar
      Returns:
      true if this calendar has a default century.
      Status:
      Internal. This API is ICU internal only.

    • getActualMaximum

      public int getActualMaximum(int field)
      Return the maximum value that this field could have, given the current date. For example, with the date "Feb 3, 1997" and the DAY_OF_MONTH field, the actual maximum would be 28; for "Feb 3, 1996" it s 29. Similarly for a Hebrew calendar, for some years the actual maximum for MONTH is 12, and for others 13.
      Overrides:
      getActualMaximum in class GregorianCalendar
      Parameters:
      field - the field whose maximum is desired
      Returns:
      the maximum of the given field for the current date of this calendar
      See Also:
      Status:
      Stable ICU 4.0.

    • isEra0CountingBackward

      @Deprecated protected boolean isEra0CountingBackward()
      Deprecated.
      This API is ICU internal only.
      The year in this calendar is counting from 1 backward if the era is 0.
      Overrides:
      isEra0CountingBackward in class GregorianCalendar
      Returns:
      The year in era 0 of this calendar is counting backward from 1.
      Status:
      Internal. This API is ICU internal only.