Package org.apache.commons.collections.functors

Class 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:
    Serialized Form

    • 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:
        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