Class ConstantTransformer

  • All Implemented Interfaces:
    Serializable, Transformer

    public class ConstantTransformer
    extends Object
    implements Transformer, Serializable
    Transformer implementation that returns the same constant each time.

    No check is made that the object is immutable. In general, only immutable objects should use the constant factory. Mutable objects should use the prototype factory.

    Since:
    Commons Collections 3.0
    Version:
    $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
    Author:
    Stephen Colebourne
    See Also:
    Serialized Form
    • Field Detail

      • NULL_INSTANCE

        public static final Transformer NULL_INSTANCE
        Returns null each time
    • Constructor Detail

      • ConstantTransformer

        public ConstantTransformer​(Object constantToReturn)
        Constructor that performs no validation. Use getInstance if you want that.
        Parameters:
        constantToReturn - the constant to return each time
    • Method Detail

      • getInstance

        public static Transformer getInstance​(Object constantToReturn)
        Transformer method that performs validation.
        Parameters:
        constantToReturn - the constant object to return each time in the factory
        Returns:
        the constant factory.
      • transform

        public Object transform​(Object input)
        Transforms the input by ignoring it and returning the stored constant instead.
        Specified by:
        transform in interface Transformer
        Parameters:
        input - the input object which is ignored
        Returns:
        the stored constant
      • getConstant

        public Object getConstant()
        Gets the constant.
        Returns:
        the constant
        Since:
        Commons Collections 3.1