org.apache.commons.collections.functors

Class SwitchTransformer

Implemented Interfaces:
Serializable, Transformer

public class SwitchTransformer
extends java.lang.Object
implements Transformer, Serializable

Transformer implementation calls the transformer whose predicate returns true, like a switch statement.
Version:
$Revision: 1.5 $ $Date: 2004/05/16 11:36:31 $
Author:
Stephen Colebourne
Since:
Commons Collections 3.0

Constructor Summary

SwitchTransformer(Predicate[] predicates, Transformer[] transformers, Transformer defaultTransformer)
Constructor that performs no validation.

Method Summary

Transformer
getDefaultTransformer()
Gets the default transformer.
static Transformer
getInstance(Map predicatesAndTransformers)
Create a new Transformer that calls one of the transformers depending on the predicates.
static Transformer
getInstance(Predicate[] predicates, Transformer[] transformers, Transformer defaultTransformer)
Factory method that performs validation and copies the parameter arrays.
Predicate[]
getPredicates()
Gets the predicates, do not modify the array.
Transformer[]
getTransformers()
Gets the transformers, do not modify the array.
Object
transform(Object input)
Transforms the input to result by calling the transformer whose matching predicate returns true.

Constructor Details

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 nop

Method Details

getDefaultTransformer

public Transformer getDefaultTransformer()
Gets the default transformer.
Returns:
the default transformer
Since:
Commons Collections 3.1

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

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 nop
Returns:
the chained transformer

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.
Specified by:
transform in interface Transformer
Parameters:
input - the input object to transform
Returns:
the transformed result

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