org.apache.commons.collections.functors
Class ConstantTransformer

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

All Implemented Interfaces:

java.io.Serializable, Transformer

public class ConstantTransformer
extends java.lang.Object
implements Transformer, java.io.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 13:33:15 +0100 (Thu, 10 Apr 2008) $

Author:

Stephen Colebourne

See Also:

Serialized Form

Field Summary

static Transformer

NULL_INSTANCE Returns null each time

Constructor Summary

ConstantTransformer(java.lang.Object constantToReturn)
Constructor that performs no validation.

Method Summary

java.lang.Object	getConstant() Gets the constant.
static Transformer	getInstance(java.lang.Object constantToReturn) Transformer method that performs validation.
java.lang.Object	transform(java.lang.Object input) Transforms the input by ignoring it and returning the stored constant instead.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NULL_INSTANCE

public static final Transformer NULL_INSTANCE

Returns null each time

Constructor Detail

ConstantTransformer

public ConstantTransformer(java.lang.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(java.lang.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 java.lang.Object transform(java.lang.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 java.lang.Object getConstant()

Gets the constant.

Returns:

the constant

Since:

Commons Collections 3.1