org.apache.commons.collections.map

## Class TransformedMap

- java.lang.Object
- - org.apache.commons.collections.map.AbstractMapDecorator
  - - org.apache.commons.collections.map.TransformedMap

- All Implemented Interfaces:
    Serializable, Map
  Direct Known Subclasses:
    TransformedSortedMap

      public class TransformedMap
      extends AbstractMapDecorator
      implements Serializable

  Decorates another `Map` to transform objects that are added.

  The Map put methods and Map.Entry setValue method are affected by this class. Thus objects must be removed or searched for using their transformed form. For example, if the transformation converts Strings to Integers, you must use the Integer form to remove objects.

  Note that TransformedMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. The simplest approach is to wrap this map using `Collections.synchronizedMap(Map)`. This class may throw exceptions when accessed by concurrent threads without synchronization.

  This class is Serializable from Commons Collections 3.1.

  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

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from interface java.util.Map

      `Map.Entry`

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected Transformer` | `keyTransformer` The transformer to use for the key
    `protected Transformer` | `valueTransformer` The transformer to use for the value

    - ### Fields inherited from class org.apache.commons.collections.map.AbstractMapDecorator

      `map`

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `TransformedMap(Map map, Transformer keyTransformer, Transformer valueTransformer)` Constructor that wraps (not copies).

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected Object` | `checkSetValue(Object value)` Override to transform the value when using `setValue`.
    `static Map` | `decorate(Map map, Transformer keyTransformer, Transformer valueTransformer)` Factory method to create a transforming map.
    `static Map` | `decorateTransform(Map map, Transformer keyTransformer, Transformer valueTransformer)` Factory method to create a transforming map that will transform existing contents of the specified map.
    `Set` | `entrySet()`
    `protected boolean` | `isSetValueChecking()` Override to only return true when there is a value transformer.
    `Object` | `put(Object key, Object value)`
    `void` | `putAll(Map mapToCopy)`
    `protected Object` | `transformKey(Object object)` Transforms a key.
    `protected Map` | `transformMap(Map map)` Transforms a map.
    `protected Object` | `transformValue(Object object)` Transforms a value.

    - ### Methods inherited from class org.apache.commons.collections.map.AbstractMapDecorator

      `clear, containsKey, containsValue, equals, get, getMap, hashCode, isEmpty, keySet, remove, size, toString, values`

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### keyTransformer

          protected final Transformer keyTransformer

      The transformer to use for the key

    - #### valueTransformer

          protected final Transformer valueTransformer

      The transformer to use for the value

  - ### Constructor Detail

    - #### TransformedMap

          protected TransformedMap(Map map,
                        Transformer keyTransformer,
                        Transformer valueTransformer)

      Constructor that wraps (not copies).

      If there are any elements already in the collection being decorated, they are NOT transformed.

      Parameters:
        `map` - the map to decorate, must not be null
        `keyTransformer` - the transformer to use for key conversion, null means no conversion
        `valueTransformer` - the transformer to use for value conversion, null means no conversion
      Throws:
        `IllegalArgumentException` - if map is null

  - ### Method Detail

    - #### decorate

          public static Map decorate(Map map,
                     Transformer keyTransformer,
                     Transformer valueTransformer)

      Factory method to create a transforming map.

      If there are any elements already in the map being decorated, they are NOT transformed. Constrast this with `decorateTransform(java.util.Map, org.apache.commons.collections.Transformer, org.apache.commons.collections.Transformer)`.

      Parameters:
        `map` - the map to decorate, must not be null
        `keyTransformer` - the transformer to use for key conversion, null means no transformation
        `valueTransformer` - the transformer to use for value conversion, null means no transformation
      Throws:
        `IllegalArgumentException` - if map is null

    - #### decorateTransform

          public static Map decorateTransform(Map map,
                              Transformer keyTransformer,
                              Transformer valueTransformer)

      Factory method to create a transforming map that will transform existing contents of the specified map.

      If there are any elements already in the map being decorated, they will be transformed by this method. Constrast this with `decorate(java.util.Map, org.apache.commons.collections.Transformer, org.apache.commons.collections.Transformer)`.

      Parameters:
        `map` - the map to decorate, must not be null
        `keyTransformer` - the transformer to use for key conversion, null means no transformation
        `valueTransformer` - the transformer to use for value conversion, null means no transformation
      Throws:
        `IllegalArgumentException` - if map is null
      Since:
        Commons Collections 3.2

    - #### transformKey

          protected Object transformKey(Object object)

      Transforms a key.

      The transformer itself may throw an exception if necessary.

      Parameters:
        `object` - the object to transform
      Throws:
        `the` - transformed object

    - #### transformValue

          protected Object transformValue(Object object)

      Transforms a value.

      The transformer itself may throw an exception if necessary.

      Parameters:
        `object` - the object to transform
      Throws:
        `the` - transformed object

    - #### transformMap

          protected Map transformMap(Map map)

      Transforms a map.

      The transformer itself may throw an exception if necessary.

      Parameters:
        `map` - the map to transform
      Throws:
        `the` - transformed object

    - #### checkSetValue

          protected Object checkSetValue(Object value)

      Override to transform the value when using `setValue`.
      Parameters:
        `value` - the value to transform
      Returns:
        the transformed value
      Since:
        Commons Collections 3.1

    - #### isSetValueChecking

          protected boolean isSetValueChecking()

      Override to only return true when there is a value transformer.
      Returns:
        true if a value transformer is in use
      Since:
        Commons Collections 3.1

    - #### put

          public Object put(Object key,
                   Object value)

      Specified by:
        `put` in interface `Map`
      Overrides:
        `put` in class `AbstractMapDecorator`

    - #### putAll

          public void putAll(Map mapToCopy)

      Specified by:
        `putAll` in interface `Map`
      Overrides:
        `putAll` in class `AbstractMapDecorator`

    - #### entrySet

          public Set entrySet()

      Specified by:
        `entrySet` in interface `Map`
      Overrides:
        `entrySet` in class `AbstractMapDecorator`

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