Class DefaultPrimeMeridian

  • All Implemented Interfaces:
    Serializable, Deprecable, Lenient­Comparable, Prime­Meridian, Identified­Object

    public class DefaultPrimeMeridian
    extends AbstractIdentifiedObject
    implements PrimeMeridian
    Defines the origin from which longitude values are determined.
    Creating new prime meridian instances
    New instances can be created either directly by specifying all information to a factory method (choices 3 and 4 below), or indirectly by specifying the identifier of an entry in a database (choices 1 and 2 below). In particular, the EPSG database provides definitions for many prime meridians, and Apache SIS provides convenience shortcuts for some of them.

    Choice 1 in the following list is the easiest but most restrictive way to get a prime meridian. The other choices provide more freedom. Each choice delegates its work to the subsequent items (in the default configuration), so this list can been seen as top to bottom API.

    1. Create a Prime­Meridian from one of the static convenience shortcuts listed in Common­CRS​.prime­Meridian().
    2. Create a Prime­Meridian from an identifier in a database by invoking Datum­Authority­Factory​.create­Prime­Meridian(String).
    3. Create a Prime­Meridian by invoking the Datum­Factory​.create­Prime­Meridian(…) method (implemented for example by Geodetic­Object­Factory).
    4. Create a Default­Prime­Meridian by invoking the constructor.
    Example: the following code gets the Greenwich prime meridian:
    PrimeMeridian pm = CommonCRS.WGS84.primeMeridian();
    Immutability and thread safety
    This class is immutable and thus thread-safe if the property values (not necessarily the map itself) given to the constructor are also immutable. Unless otherwise noted in the javadoc, this condition holds if all components were created using only SIS factories and static constants.
    Since:
    0.4
    See Also:
    Common­CRS​.prime­Meridian(), Geodetic­Authority­Factory​.create­Prime­Meridian(String), Serialized Form

    Defined in the sis-referencing module

    • Method Detail

      • castOrCopy

        public static DefaultPrimeMeridian castOrCopy​(PrimeMeridian object)
        Returns a SIS prime meridian implementation with the same values than the given arbitrary implementation. If the given object is null, then this method returns null. Otherwise if the given object is already a SIS implementation, then the given object is returned unchanged. Otherwise a new SIS implementation is created and initialized to the attribute values of the given object.
        Parameters:
        object - the object to get as a SIS implementation, or null if none.
        Returns:
        a SIS implementation containing the values of the given object (may be the given object itself), or null if the argument was null.
      • getInterface

        public Class<? extends PrimeMeridian> getInterface()
        Returns the GeoAPI interface implemented by this class. The SIS implementation returns Prime­Meridian​.class.
        Note for implementers: Subclasses usually do not need to override this method since GeoAPI does not define Prime­Meridian sub-interface. Overriding possibility is left mostly for implementers who wish to extend GeoAPI with their own set of interfaces.
        Overrides:
        get­Interface in class Abstract­Identified­Object
        Returns:
        Prime­Meridian​.class or a user-defined sub-interface.
      • getGreenwichLongitude

        public double getGreenwichLongitude()
        Longitude of the prime meridian measured from the Greenwich meridian, positive eastward.
        Specified by:
        get­Greenwich­Longitude in interface Prime­Meridian
        Returns:
        the prime meridian Greenwich longitude, in angular unit.
      • getGreenwichLongitude

        public double getGreenwichLongitude​(Unit<Angle> unit)
        Returns the longitude value relative to the Greenwich Meridian, expressed in the specified units. This convenience method makes it easier to obtain longitude in decimal degrees using the following code, regardless of the underlying angular units of this prime meridian:
        double longitudeInDegrees = primeMeridian.getGreenwichLongitude(Units.DEGREE);
        Parameters:
        unit - the unit in which to express longitude.
        Returns:
        the Greenwich longitude in the given units.