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

    • serialVersionUID

      private static final long serialVersionUID
      Serial version UID
      See Also:

    • NULL_INSTANCE

      public static final Transformer NULL_INSTANCE
      Returns null each time

    • iConstant

      private final O iConstant
      The closures to call in turn

  • 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

    • nullTransformer

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

    • 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.

    • 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

    • getConstant

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

    • equals

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

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object