org.apache.commons.collections.functors

Class SwitchTransformer

public class SwitchTransformer extends Object implements Transformer, Serializable

Transformer implementation calls the transformer whose predicate returns true, like a switch statement.

Since: Commons Collections 3.0

Version: $Revision: 393105 $ $Date: 2006-04-10 23:23:11 +0100 (Mon, 10 Apr 2006) $

Author: Stephen Colebourne

Constructor Summary
SwitchTransformer(Predicate[] predicates, Transformer[] transformers, Transformer defaultTransformer)
Constructor that performs no validation.
Method Summary
TransformergetDefaultTransformer()
Gets the default transformer.
static TransformergetInstance(Predicate[] predicates, Transformer[] transformers, Transformer defaultTransformer)
Factory method that performs validation and copies the parameter arrays.
static TransformergetInstance(Map predicatesAndTransformers)
Create a new Transformer that calls one of the transformers depending on the predicates.
Predicate[]getPredicates()
Gets the predicates, do not modify the array.
Transformer[]getTransformers()
Gets the transformers, do not modify the array.
Objecttransform(Object input)
Transforms the input to result by calling the transformer whose matching predicate returns true.

Constructor Detail

SwitchTransformer

public SwitchTransformer(Predicate[] predicates, Transformer[] transformers, Transformer defaultTransformer)
Constructor that performs no validation. Use getInstance if you want that.

Parameters: predicates array of predicates, not cloned, no nulls transformers matching array of transformers, not cloned, no nulls defaultTransformer the transformer to use if no match, null means return null

Method Detail

getDefaultTransformer

public Transformer getDefaultTransformer()
Gets the default transformer.

Returns: the default transformer

Since: Commons Collections 3.1

getInstance

public static Transformer getInstance(Predicate[] predicates, Transformer[] transformers, Transformer defaultTransformer)
Factory method that performs validation and copies the parameter arrays.

Parameters: predicates array of predicates, cloned, no nulls transformers matching array of transformers, cloned, no nulls defaultTransformer the transformer to use if no match, null means return null

Returns: the chained transformer

Throws: IllegalArgumentException if array is null IllegalArgumentException if any element in the array is null

getInstance

public static Transformer getInstance(Map predicatesAndTransformers)
Create a new Transformer that calls one of the transformers depending on the predicates.

The Map consists of Predicate keys and Transformer values. A transformer is called if its matching predicate returns true. Each predicate is evaluated until one returns true. If no predicates evaluate to true, the default transformer is called. The default transformer is set in the map with a null key. The ordering is that of the iterator() method on the entryset collection of the map.

Parameters: predicatesAndTransformers a map of predicates to transformers

Returns: the switch transformer

Throws: IllegalArgumentException if the map is null IllegalArgumentException if any transformer in the map is null ClassCastException if the map elements are of the wrong type

getPredicates

public Predicate[] getPredicates()
Gets the predicates, do not modify the array.

Returns: the predicates

Since: Commons Collections 3.1

getTransformers

public Transformer[] getTransformers()
Gets the transformers, do not modify the array.

Returns: the transformers

Since: Commons Collections 3.1

transform

public Object transform(Object input)
Transforms the input to result by calling the transformer whose matching predicate returns true.

Parameters: input the input object to transform

Returns: the transformed result

Copyright © 2001-2008 Apache Software Foundation. All Rights Reserved.