org.apache.commons.collections.functors

Class ConstantTransformer

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: 348444 $ $Date: 2005-11-23 14:06:56 +0000 (Wed, 23 Nov 2005) $

Author: Stephen Colebourne

Field Summary
static TransformerNULL_INSTANCE
Returns null each time
Constructor Summary
ConstantTransformer(Object constantToReturn)
Constructor that performs no validation.
Method Summary
ObjectgetConstant()
Gets the constant.
static TransformergetInstance(Object constantToReturn)
Transformer method that performs validation.
Objecttransform(Object input)
Transforms the input by ignoring it and returning the stored constant instead.

Field Detail

NULL_INSTANCE

public static final Transformer NULL_INSTANCE
Returns null each time

Constructor Detail

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 Detail

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.

Parameters: input the input object which is ignored

Returns: the stored constant

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