Package org.apache.commons.collections.functors

Class ConstantTransformer

java.lang.Object
org.apache.commons.collections.functors.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:

  • Field Details

    • NULL_INSTANCE

      public static final Transformer NULL_INSTANCE
      Returns null each time

  • Constructor Details

    • 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 Details

    • 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