org.apache.commons.collections.functors
Class SwitchTransformer

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

All Implemented Interfaces:

java.io.Serializable, Transformer

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

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

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

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

Methods inherited from class java.lang.Object

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

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

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:

java.lang.IllegalArgumentException - if array is null

java.lang.IllegalArgumentException - if any element in the array is null

getInstance

public static Transformer getInstance(java.util.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:

java.lang.IllegalArgumentException - if the map is null

java.lang.IllegalArgumentException - if any transformer in the map is null

java.lang.ClassCastException - if the map elements are of the wrong type

transform

public java.lang.Object transform(java.lang.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

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

getDefaultTransformer

public Transformer getDefaultTransformer()

Gets the default transformer.

Returns:

the default transformer

Since:

Commons Collections 3.1