Package org.apache.sis.referencing

## Enum CommonCRS.Temporal

- Object
- - Enum<CommonCRS.Temporal>
  - - Temporal

- All Implemented Interfaces:
    `Serializable`, `Comparable<CommonCRS​.Temporal>`
  Enclosing class:
    CommonCRS

      public static enum CommonCRS.Temporal
      extends Enum<CommonCRS.Temporal>

  Frequently-used temporal CRS and datum that are guaranteed to be available in SIS.

  Referencing objects are cached after creation. Invoking the same method on the same `Temporal` instance twice will return the same `IdentifiedObject` instance, unless the internal cache has been cleared (e.g. the application is running in a container environment and some modules have been installed or uninstalled).

  Example: the following code fetches a temporal Coordinate Reference System using the Julian calendar:

  >     TemporalCRS crs = CommonCRS.Temporal.JULIAN.crs();

  Below is an alphabetical list of object names available in this enumeration:

  > Temporal objects accessible by enumeration constants
  > Name or alias | Object type | Enumeration value
  > --- | --- | ---
  > Dublin Julian | CRS, Datum | `DUBLIN_JULIAN`
  > Java time | CRS | `JAVA`
  > Julian | CRS, Datum | `JULIAN`
  > Modified Julian | CRS, Datum | `MODIFIED_JULIAN`
  > Truncated Julian | CRS, Datum | `TRUNCATED_JULIAN`
  > Unix/POSIX time | CRS, Datum | `UNIX`

  Since:
    0.4

  Defined in the `sis-referencing` module

- - ### Enum Constant Summary

    Enum Constants
    Enum Constant | Description
    --- | ---
    `DUBLIN_JULIAN` | Time measured as days since December 31, 1899 at 12:00 UTC.
    `JAVA` | Time measured as milliseconds since January 1st, 1970 at 00:00 UTC.
    `JULIAN` | Time measured as days since January 1st, 4713 BC at 12:00 UTC in proleptic Julian calendar.
    `MODIFIED_JULIAN` | Time measured as days since November 17, 1858 at 00:00 UTC.
    `TRUNCATED_JULIAN` | Time measured as days since May 24, 1968 at 00:00 UTC.
    `UNIX` | Time measured as seconds since January 1st, 1970 at 00:00 UTC.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `TemporalCRS` | `crs()` | Returns the coordinate reference system associated to this temporal object.
    `TemporalDatum` | `datum()` | Returns the datum associated to this temporal object.
    `static CommonCRS.Temporal` | `forEpoch​(Instant epoch)` | Returns the enumeration value for the given epoch, or `null` if none.
    `static CommonCRS.Temporal` | `valueOf​(String name)` | Returns the enum constant of this type with the specified name.
    `static CommonCRS.Temporal[]` | `values()` | Returns an array containing the constants of this enum type, in the order they are declared.

    - ### Methods inherited from class Enum

      `clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf`

    - ### Methods inherited from class Object

      `getClass, notify, notifyAll, wait, wait, wait`

- - ### Enum Constant Detail

    - #### JULIAN

          public static final CommonCRS.Temporal JULIAN

      Time measured as days since January 1st, 4713 BC at 12:00 UTC in proleptic Julian calendar. This epoch is equivalent to November 24, 4714 BC when expressed in the proleptic Gregorian calendar instead than the Julian one.

      Note on dates formatting: the legacy date/time formatting classes in the `java​.text` package uses the proleptic Julian calendar for dates before October 15, 1582, while the new date/time formatting classes in the `java​.time​.format` package use the ISO-8601 calendar system, which is equivalent to the proleptic Gregorian calendar for every dates. For parsing and formatting of Julian days, the `SimpleDateFormat` class is closer to the common practice (but not ISO 8601 compliant).

    - #### MODIFIED_JULIAN

          public static final CommonCRS.Temporal MODIFIED_JULIAN

      Time measured as days since November 17, 1858 at 00:00 UTC. A Modified Julian day (MJD) is defined relative to Julian day (JD) as `MJD = JD − 2400000.5`.

    - #### TRUNCATED_JULIAN

          public static final CommonCRS.Temporal TRUNCATED_JULIAN

      Time measured as days since May 24, 1968 at 00:00 UTC. This epoch was introduced by NASA for the space program. A Truncated Julian day (TJD) is defined relative to Julian day (JD) as `TJD = JD − 2440000.5`.

    - #### DUBLIN_JULIAN

          public static final CommonCRS.Temporal DUBLIN_JULIAN

      Time measured as days since December 31, 1899 at 12:00 UTC. A Dublin Julian day (DJD) is defined relative to Julian day (JD) as `DJD = JD − 2415020`.

    - #### UNIX

          public static final CommonCRS.Temporal UNIX

      Time measured as seconds since January 1st, 1970 at 00:00 UTC.

    - #### JAVA

          public static final CommonCRS.Temporal JAVA

      Time measured as milliseconds since January 1st, 1970 at 00:00 UTC.

  - ### Method Detail

    - #### values

          public static CommonCRS.Temporal[] values()

      Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

          for (CommonCRS.Temporal c : CommonCRS.Temporal.values())
              System.out.println(c);

      Returns:
        an array containing the constants of this enum type, in the order they are declared

    - #### valueOf

          public static CommonCRS.Temporal valueOf​(String name)

      Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
      Parameters:
        `name` - the name of the enum constant to be returned.
      Returns:
        the enum constant with the specified name
      Throws:
        `IllegalArgumentException` - if this enum type has no constant with the specified name
        `NullPointerException` - if the argument is null

    - #### forEpoch

          public static CommonCRS.Temporal forEpoch​(Instant epoch)

      Returns the enumeration value for the given epoch, or `null` if none. If the epoch is January 1st, 1970, then this method returns `UNIX`.
      Parameters:
        `epoch` - the epoch for which to get an enumeration value, or `null`.
      Returns:
        the enumeration value for the given epoch, or `null` if none.
      Since:
        1.0

    - #### crs

          public TemporalCRS crs()

      Returns the coordinate reference system associated to this temporal object. The following table summarizes the CRS known to this class, together with an enumeration value that can be used for fetching that CRS:

      > Commonly used temporal CRS
      > Name or alias | Enum
      > --- | ---
      > Dublin Julian | `DUBLIN_JULIAN`
      > Julian | `JULIAN`
      > Modified Julian | `MODIFIED_JULIAN`
      > Truncated Julian | `TRUNCATED_JULIAN`
      > Unix/POSIX or Java | `UNIX`

      Returns:
        the CRS associated to this enum.
      See Also:
        `DefaultTemporalCRS`

    - #### datum

          public TemporalDatum datum()

      Returns the datum associated to this temporal object. The following table summarizes the datum known to this class, together with an enumeration value that can be used for fetching that datum:

      > Commonly used temporal datum
      > Name or alias | Enum
      > --- | ---
      > Dublin Julian | `DUBLIN_JULIAN`
      > Julian | `JULIAN`
      > Modified Julian | `MODIFIED_JULIAN`
      > Truncated Julian | `TRUNCATED_JULIAN`
      > Unix/POSIX or Java | `UNIX`

      Returns:
        the datum associated to this enum.
      See Also:
        `DefaultTemporalDatum`