org.apache.commons.collections.functors
Class SwitchTransformer

java.lang.Object
  |
  +--org.apache.commons.collections.functors.SwitchTransformer
All Implemented Interfaces:
Serializable, Transformer

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: 1.2 $ $Date: 2004/01/14 21:43:09 $
Author:
Stephen Colebourne
See Also:
Serialized Form

Constructor Summary
SwitchTransformer(Predicate[] predicates, Transformer[] transformers, Transformer defaultTransformer)
          Constructor that performs no validation.
 
Method Summary
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.
 Object transform(Object input)
          Execute the transformer whose 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 nop
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 nop
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

transform

public Object transform(Object input)
Execute the transformer whose predicate returns true.
Specified by:
transform in interface Transformer
Following copied from interface: org.apache.commons.collections.Transformer
Parameters:
input - the object to be transformed
Returns:
a transformed object
Throws:
ClassCastException - (runtime) if the input is the wrong class
IllegalArgumentException - (runtime) if the input is invalid
FunctorException - (runtime) if the transform cannot be completed


Copyright © 2001-2004 Apache Software Foundation. All Rights Reserved.