Package 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: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
Author:
Stephen Colebourne
See Also:

  • 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 return null

  • Method Details

    • 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

    • 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

    • 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