Package org.apache.commons.collections4.functors

Class ConstantTransformer<I,O>

java.lang.Object
org.apache.commons.collections4.functors.ConstantTransformer<I,O>
All Implemented Interfaces:
Serializable, Transformer<I,O>
public class ConstantTransformer<I,O> extends Object implements Transformer<I,O>, 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:
3.0
See Also:

  • Field Details

  • Constructor Details

    • ConstantTransformer

      public ConstantTransformer(O constantToReturn)
      Constructor that performs no validation. Use constantTransformer if you want that.
      Parameters:
      constantToReturn - the constant to return each time

  • Method Details

    • constantTransformer

      public static <I, O> Transformer<I,O> constantTransformer(O constantToReturn)
      Transformer method that performs validation.
      Type Parameters:
      I - the input type
      O - the output type
      Parameters:
      constantToReturn - the constant object to return each time in the factory
      Returns:
      the constant factory.

    • nullTransformer

      public static <I, O> Transformer<I,O> nullTransformer()
      Gets a typed null instance.
      Type Parameters:
      I - the input type
      O - the output type
      Returns:
      Transformer<I, O> that always returns null.

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object

    • getConstant

      public O getConstant()
      Gets the constant.
      Returns:
      the constant
      Since:
      3.1

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • transform

      public O transform(I input)
      Transforms the input by ignoring it and returning the stored constant instead.
      Specified by:
      transform in interface Transformer<I,O>
      Parameters:
      input - the input object which is ignored
      Returns:
      the stored constant