Module java.base
Package java.time.chrono

# Class JapaneseEra

java.lang.Object
java.time.chrono.JapaneseEra

All Implemented Interfaces:
  `Serializable`, `Era`, `TemporalAccessor`, `TemporalAdjuster`

public final class JapaneseEra extends Object implements Era, Serializable
An era in the Japanese Imperial calendar system.

The Japanese government defines the official name and start date of each era. Eras are consecutive and their date ranges do not overlap, so the end date of one era is always the day before the start date of the next era.

The Java SE Platform supports all eras defined by the Japanese government, beginning with the Meiji era. Each era is identified in the Platform by an integer value and a name. The `of(int)` and `valueOf(String)` methods may be used to obtain a singleton instance of `JapaneseEra` for each era. The `values()` method returns the singleton instances of all supported eras.

For convenience, this class declares a number of public static final fields that refer to singleton instances returned by the `values()` method.

API Note:
  The fields declared in this class may evolve over time, in line with the results of the `values()` method. However, there is not necessarily a 1:1 correspondence between the fields and the singleton instances., The Japanese government may announce a new era and define its start date but not its official name. In this scenario, the singleton instance that represents the new era may return a name that is not stable until the official name is defined. Developers should exercise caution when relying on the name returned by any singleton instance that does not correspond to a public static final field.
Implementation Requirements:
  This class is immutable and thread-safe.
Since:
  1.8
See Also:
  - Serialized Form

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final JapaneseEra`
  `HEISEI`
  The singleton instance for the 'Heisei' era (1989-01-08 - 2019-04-30) which has the value 2.
  `static final JapaneseEra`
  `MEIJI`
  The singleton instance for the 'Meiji' era (1868-01-01 - 1912-07-29) which has the value -1.
  `static final JapaneseEra`
  `REIWA`
  The singleton instance for the 'Reiwa' era (2019-05-01 - ) which has the value 3.
  `static final JapaneseEra`
  `SHOWA`
  The singleton instance for the 'Showa' era (1926-12-25 - 1989-01-07) which has the value 1.
  `static final JapaneseEra`
  `TAISHO`
  The singleton instance for the 'Taisho' era (1912-07-30 - 1926-12-24) which has the value 0.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `String`
  `getDisplayName(TextStyle style, Locale locale)`
  Gets the textual representation of this era.
  `int`
  `getValue()`
  Gets the numeric era `int` value.
  `static JapaneseEra`
  `of(int japaneseEra)`
  Obtains an instance of `JapaneseEra` from an `int` value.
  `ValueRange`
  `range(TemporalField field)`
  Gets the range of valid values for the specified field.
  `static JapaneseEra`
  `valueOf(String japaneseEra)`
  Returns the `JapaneseEra` with the name.
  `static JapaneseEra[]`
  `values()`
  Returns an array of JapaneseEras.

  ### Methods declared in class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

  ### Methods declared in interface java.time.chrono.Era

  `adjustInto, get, getLong, isSupported, query`

- ## Field Details

  - ### MEIJI

    public static final JapaneseEra MEIJI
    The singleton instance for the 'Meiji' era (1868-01-01 - 1912-07-29) which has the value -1.

  - ### TAISHO

    public static final JapaneseEra TAISHO
    The singleton instance for the 'Taisho' era (1912-07-30 - 1926-12-24) which has the value 0.

  - ### SHOWA

    public static final JapaneseEra SHOWA
    The singleton instance for the 'Showa' era (1926-12-25 - 1989-01-07) which has the value 1.

  - ### HEISEI

    public static final JapaneseEra HEISEI
    The singleton instance for the 'Heisei' era (1989-01-08 - 2019-04-30) which has the value 2.

  - ### REIWA

    public static final JapaneseEra REIWA
    The singleton instance for the 'Reiwa' era (2019-05-01 - ) which has the value 3. The end date of this era is not specified, unless the Japanese Government defines it.
    Since:
      13

- ## Method Details

  - ### of

    public static JapaneseEra of(int japaneseEra)
    Obtains an instance of `JapaneseEra` from an `int` value.
    - The value `1` is associated with the 'Showa' era, because it contains 1970-01-01 (ISO calendar system).
    - The values `-1` and `0` are associated with two earlier eras, Meiji and Taisho, respectively.
    - A value greater than `1` is associated with a later era, beginning with Heisei (`2`).

    Every instance of `JapaneseEra` that is returned from the `values()` method has an int value (available via `Era.getValue()` which is accepted by this method.

    Parameters:
      `japaneseEra` - the era to represent
    Returns:
      the `JapaneseEra` singleton, not null
    Throws:
      `DateTimeException` - if the value is invalid

  - ### valueOf

    public static JapaneseEra valueOf(String japaneseEra)
    Returns the `JapaneseEra` with the name.

    The string must match exactly the name of the era. (Extraneous whitespace characters are not permitted.)

    Valid era names are the names of eras returned from `values()`.

    Parameters:
      `japaneseEra` - the japaneseEra name; non-null
    Returns:
      the `JapaneseEra` singleton, never null
    Throws:
      `IllegalArgumentException` - if there is not JapaneseEra with the specified name

  - ### values

    public static JapaneseEra[] values()
    Returns an array of JapaneseEras. The array may contain eras defined by the Japanese government beyond the known era singletons.

    This method may be used to iterate over the JapaneseEras as follows:

         for (JapaneseEra c : JapaneseEra.values())
             System.out.println(c);

    Returns:
      an array of JapaneseEras

  - ### getDisplayName

    public String getDisplayName(TextStyle style, Locale locale)
    Gets the textual representation of this era.

    This returns the textual name used to identify the era, suitable for presentation to the user. The parameters control the style of the returned text and the locale.

    If no textual mapping is found then the `numeric value` is returned.

    Specified by:
      `getDisplayName` in interface `Era`
    Parameters:
      `style` - the style of the text required, not null
      `locale` - the locale to use, not null
    Returns:
      the text value of the era, not null

  - ### getValue

    public int getValue()
    Gets the numeric era `int` value.

    The `SHOWA` era that contains 1970-01-01 (ISO calendar system) has the value 1. Later eras are numbered from 2 (`HEISEI`). Earlier eras are numbered 0 (`TAISHO`), -1 (`MEIJI`)).

    Specified by:
      `getValue` in interface `Era`
    Returns:
      the era value

  - ### range

    public ValueRange range(TemporalField field)
    Gets the range of valid values for the specified field.

    The range object expresses the minimum and maximum valid values for a field. This era is used to enhance the accuracy of the returned range. If it is not possible to return the range, because the field is not supported or for some other reason, an exception is thrown.

    If the field is a `ChronoField` then the query is implemented here. The `ERA` field returns the range. All other `ChronoField` instances will throw an `UnsupportedTemporalTypeException`.

    If the field is not a `ChronoField`, then the result of this method is obtained by invoking `TemporalField.rangeRefinedBy(TemporalAccessor)` passing `this` as the argument. Whether the range can be obtained is determined by the field.

    The range of valid Japanese eras can change over time due to the nature of the Japanese calendar system.

    Specified by:
      `range` in interface `Era`
    Specified by:
      `range` in interface `TemporalAccessor`
    Parameters:
      `field` - the field to query the range for, not null
    Returns:
      the range of valid values for the field, not null
    Throws:
      `DateTimeException` - if the range for the field cannot be obtained
      `UnsupportedTemporalTypeException` - if the unit is not supported