org.apache.commons.collections.functors

Class ConstantTransformer

Implemented Interfaces:
Serializable, Transformer

public class ConstantTransformer
extends java.lang.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.

Version:
$Revision: 1.5 $ $Date: 2004/05/16 11:36:31 $
Author:
Stephen Colebourne
Since:
Commons Collections 3.0

Field Summary

static Transformer
NULL_INSTANCE
Returns null each time

Constructor Summary

ConstantTransformer(Object constantToReturn)
Constructor that performs no validation.

Method Summary

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

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

getConstant

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

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

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