Package org.apache.commons.collections4.map

Class TransformedMap<K,​V>

  • Type Parameters:
    K - the type of the keys in this map
    V - the type of the values in this map
    All Implemented Interfaces:
    Serializable, Map<K,​V>, Get<K,​V>, IterableGet<K,​V>, IterableMap<K,​V>, Put<K,​V>
    Direct Known Subclasses:
    TransformedSortedMap
    public class TransformedMap<K,​V>
extends AbstractMapDecorator<K,​V>
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:
    3.0
    See Also:
    TransformedSplitMap, Serialized Form

    • Field Detail

      • keyTransformer

        protected final Transformer<? super K,​? extends K> keyTransformer
        The transformer to use for the key

      • valueTransformer

        protected final Transformer<? super V,​? extends V> valueTransformer
        The transformer to use for the value

    • Constructor Detail

      • TransformedMap

        protected TransformedMap​(Map<K,​V> map,
                         Transformer<? super K,​? extends K> keyTransformer,
                         Transformer<? super V,​? extends V> 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:
        NullPointerException - if map is null

    • Method Detail

      • transformingMap

        public static <K,​V> TransformedMap<K,​V> transformingMap​(Map<K,​V> map,
                                                                    Transformer<? super K,​? extends K> keyTransformer,
                                                                    Transformer<? super V,​? extends V> valueTransformer)
        Factory method to create a transforming map.

        If there are any elements already in the map being decorated, they are NOT transformed. Contrast this with transformedMap(Map, Transformer, Transformer).

        Type Parameters:
        K - the key type
        V - the value type
        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
        Returns:
        a new transformed map
        Throws:
        NullPointerException - if map is null
        Since:
        4.0

      • transformedMap

        public static <K,​V> TransformedMap<K,​V> transformedMap​(Map<K,​V> map,
                                                                   Transformer<? super K,​? extends K> keyTransformer,
                                                                   Transformer<? super V,​? extends V> 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. Contrast this with transformingMap(Map, Transformer, Transformer).

        Type Parameters:
        K - the key type
        V - the value type
        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
        Returns:
        a new transformed map
        Throws:
        NullPointerException - if map is null
        Since:
        4.0

      • transformKey

        protected K transformKey​(K object)
        Transforms a key.

        The transformer itself may throw an exception if necessary.

        Parameters:
        object - the object to transform
        Returns:
        the transformed object

      • transformValue

        protected V transformValue​(V object)
        Transforms a value.

        The transformer itself may throw an exception if necessary.

        Parameters:
        object - the object to transform
        Returns:
        the transformed object

      • transformMap

        protected Map<K,​V> transformMap​(Map<? extends K,​? extends V> map)
        Transforms a map.

        The transformer itself may throw an exception if necessary.

        Parameters:
        map - the map to transform
        Returns:
        the transformed object

      • checkSetValue

        protected V checkSetValue​(V value)
        Override to transform the value when using setValue.
        Parameters:
        value - the value to transform
        Returns:
        the transformed value
        Since:
        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:
        3.1

      • put

        public V put​(K key,
             V value)
        Description copied from interface: Put
        Note that the return type is Object, rather than V as in the Map interface. See the class Javadoc for further info.
        Specified by:
        put in interface Map<K,​V>
        Specified by:
        put in interface Put<K,​V>
        Overrides:
        put in class AbstractMapDecorator<K,​V>
        Parameters:
        key - key with which the specified value is to be associated
        value - value to be associated with the specified key
        Returns:
        the previous value associated with key, or null if there was no mapping for key. (A null return can also indicate that the map previously associated null with key, if the implementation supports null values.)
        See Also:
        Map.put(Object, Object)