Enum DummyLookup

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Comparable<DummyLookup>, Lookup

    public enum DummyLookup
    extends java.lang.Enum<DummyLookup>
    implements Lookup

    A simple dummy Lookup implementation.

    This implementation always returns null for a passed in variable indicating that it cannot resolve that variable. This is useful for instance as an application of the null object pattern.

    This class does not define any state, therefore a single instance can be shared. To enforce usage of only a single instance this class is actually an enumeration.

    Since:
    2.0
    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description
      INSTANCE
      The single instance of this class.
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.lang.Object lookup​(java.lang.String variable)
      Looks up the value of the specified variable.
      static DummyLookup valueOf​(java.lang.String name)
      Returns the enum constant of this type with the specified name.
      static DummyLookup[] values()
      Returns an array containing the constants of this enum type, in the order they are declared.
      • Methods inherited from class java.lang.Enum

        clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf
      • Methods inherited from class java.lang.Object

        getClass, notify, notifyAll, wait, wait, wait
    • Enum Constant Detail

      • INSTANCE

        public static final DummyLookup INSTANCE
        The single instance of this class.
    • Method Detail

      • values

        public static DummyLookup[] 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 (DummyLookup c : DummyLookup.values())
            System.out.println(c);
        
        Returns:
        an array containing the constants of this enum type, in the order they are declared
      • valueOf

        public static DummyLookup valueOf​(java.lang.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:
        java.lang.IllegalArgumentException - if this enum type has no constant with the specified name
        java.lang.NullPointerException - if the argument is null
      • lookup

        public java.lang.Object lookup​(java.lang.String variable)
        Looks up the value of the specified variable. This method is called by ConfigurationInterpolator with the variable name extracted from the expression to interpolate (i.e. the prefix name has already been removed). A concrete implementation has to return the value of this variable or null if the variable name is unknown. This implementation always returns null.
        Specified by:
        lookup in interface Lookup
        Parameters:
        variable - the name of the variable to be resolved
        Returns:
        the value of this variable or null