org.apache.commons.collections4.splitmap
Class TransformedSplitMap<J,K,U,V>

java.lang.Object
  extended by org.apache.commons.collections4.splitmap.AbstractIterableGetMapDecorator<K,V>
      extended by org.apache.commons.collections4.splitmap.TransformedSplitMap<J,K,U,V>
All Implemented Interfaces:
Serializable, Get<K,V>, IterableGet<K,V>, Put<J,U>

public class TransformedSplitMap<J,K,U,V>
extends AbstractIterableGetMapDecorator<K,V>
implements Put<J,U>, 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.

The "put" and "get" type constraints of this class are mutually independent; contrast with TransformedMap which, by virtue of its implementing Map<K, V>, must be constructed in such a way that its read and write parameters are generalized to a common (super-)type. In practice this would often mean >Object, Object>, defeating much of the usefulness of having parameterized types.

On the downside, this class is not drop-in compatible with Map but is intended to be worked with either directly or by Put and Get generalizations.

Since:
4.0
Version:
$Id: TransformedSplitMap.java 1491944 2013-06-11 20:29:22Z tn $
See Also:
SplitMapUtils.readableMap(Get), SplitMapUtils.writableMap(Put), Serialized Form

Constructor Summary
protected TransformedSplitMap(Map<K,V> map, Transformer<? super J,? extends K> keyTransformer, Transformer<? super U,? extends V> valueTransformer)
          Constructor that wraps (not copies).
 
Method Summary
protected  V checkSetValue(U value)
          Override to transform the value when using setValue.
 void clear()
           
 V put(J key, U value)
          Note that the return type is Object, rather than V as in the Map interface.
 void putAll(Map<? extends J,? extends U> mapToCopy)
           
static
<J,K,U,V> TransformedSplitMap<J,K,U,V>
transformingMap(Map<K,V> map, Transformer<? super J,? extends K> keyTransformer, Transformer<? super U,? extends V> valueTransformer)
          Factory method to create a transforming map.
protected  K transformKey(J object)
          Transforms a key.
protected  Map<K,V> transformMap(Map<? extends J,? extends U> map)
          Transforms a map.
protected  V transformValue(U object)
          Transforms a value.
 
Methods inherited from class org.apache.commons.collections4.splitmap.AbstractIterableGetMapDecorator
containsKey, containsValue, decorated, entrySet, equals, get, hashCode, isEmpty, keySet, mapIterator, remove, size, toString, values
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Constructor Detail

TransformedSplitMap

protected TransformedSplitMap(Map<K,V> map,
                              Transformer<? super J,? extends K> keyTransformer,
                              Transformer<? super U,? 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:
IllegalArgumentException - if map is null
Method Detail

transformingMap

public static <J,K,U,V> TransformedSplitMap<J,K,U,V> transformingMap(Map<K,V> map,
                                                                     Transformer<? super J,? extends K> keyTransformer,
                                                                     Transformer<? super U,? 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.

Type Parameters:
J - the input key type
K - the output key type
U - the input value type
V - the output 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:
IllegalArgumentException - if map is null

transformKey

protected K transformKey(J 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(U 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 J,? extends U> 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(U value)
Override to transform the value when using setValue.

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

put

public V put(J key,
             U 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 Put<J,U>
See Also:
Map.put(Object, Object)

putAll

public void putAll(Map<? extends J,? extends U> mapToCopy)
Specified by:
putAll in interface Put<J,U>
See Also:
Map.putAll(Map)

clear

public void clear()
Specified by:
clear in interface Put<J,U>
See Also:
Map.clear()


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