org.apache.commons.collections.bidimap
Class UnmodifiableBidiMap

java.lang.Object
  org.apache.commons.collections.map.AbstractMapDecorator
      org.apache.commons.collections.bidimap.AbstractBidiMapDecorator
          org.apache.commons.collections.bidimap.UnmodifiableBidiMap

All Implemented Interfaces:

java.util.Map, BidiMap, IterableMap, Unmodifiable

public final class UnmodifiableBidiMap
extends AbstractBidiMapDecorator
implements Unmodifiable

Decorates another BidiMap to ensure it can't be altered.

Since:

Commons Collections 3.0

Version:

$Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $

Author:

Stephen Colebourne

Nested Class Summary

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

java.util.Map.Entry

Field Summary

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

map

Method Summary

void	clear()
static BidiMap	decorate(BidiMap map) Factory method to create an unmodifiable map.
java.util.Set	entrySet()
BidiMap	inverseBidiMap() Gets a view of this map where the keys and values are reversed.
java.util.Set	keySet()
MapIterator	mapIterator() Obtains a MapIterator over the map.
java.lang.Object	put(java.lang.Object key, java.lang.Object value) Puts the key-value pair into the map, replacing any previous pair.
void	putAll(java.util.Map mapToCopy)
java.lang.Object	remove(java.lang.Object key)
java.lang.Object	removeValue(java.lang.Object value) Removes the key-value pair that is currently mapped to the specified value (optional operation).
java.util.Collection	values()

Methods inherited from class org.apache.commons.collections.bidimap.AbstractBidiMapDecorator

getBidiMap, getKey

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

containsKey, containsValue, equals, get, getMap, hashCode, isEmpty, size, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

containsKey, containsValue, equals, get, hashCode, isEmpty, size

Method Detail

decorate

public static BidiMap decorate(BidiMap map)

Factory method to create an unmodifiable map.

If the map passed in is already unmodifiable, it is returned.

Parameters:

map - the map to decorate, must not be null

Returns:

an unmodifiable BidiMap

Throws:

java.lang.IllegalArgumentException - if map is null

clear

public void clear()

Specified by:

clear in interface java.util.Map

Overrides:

clear in class AbstractMapDecorator

put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object value)

Description copied from interface: BidiMap

Puts the key-value pair into the map, replacing any previous pair.

When adding a key-value pair, the value may already exist in the map against a different key. That mapping is removed, to ensure that the value only occurs once in the inverse map.

  BidiMap map1 = new DualHashBidiMap();
  map.put("A","B");  // contains A mapped to B, as per Map
  map.put("A","C");  // contains A mapped to C, as per Map
 
  BidiMap map2 = new DualHashBidiMap();
  map.put("A","B");  // contains A mapped to B, as per Map
  map.put("C","B");  // contains C mapped to B, key A is removed
 

Specified by:

put in interface java.util.Map

Specified by:

put in interface BidiMap

Overrides:

put in class AbstractMapDecorator

Parameters:

key - the key to store

value - the value to store

Returns:

the previous value mapped to this key

putAll

public void putAll(java.util.Map mapToCopy)

Specified by:

putAll in interface java.util.Map

Overrides:

putAll in class AbstractMapDecorator

remove

public java.lang.Object remove(java.lang.Object key)

Specified by:

remove in interface java.util.Map

Overrides:

remove in class AbstractMapDecorator

entrySet

public java.util.Set entrySet()

Specified by:

entrySet in interface java.util.Map

Overrides:

entrySet in class AbstractMapDecorator

keySet

public java.util.Set keySet()

Specified by:

keySet in interface java.util.Map

Overrides:

keySet in class AbstractMapDecorator

values

public java.util.Collection values()

Specified by:

values in interface java.util.Map

Overrides:

values in class AbstractMapDecorator

removeValue

public java.lang.Object removeValue(java.lang.Object value)

Description copied from interface: BidiMap

Removes the key-value pair that is currently mapped to the specified value (optional operation).

If the value is not contained in the map, null is returned.

Implementations should seek to make this method perform equally as well as remove(Object).

Specified by:

removeValue in interface BidiMap

Overrides:

removeValue in class AbstractBidiMapDecorator

Parameters:

value - the value to find the key-value pair for

Returns:

the key that was removed, null if nothing removed

mapIterator

public MapIterator mapIterator()

Description copied from interface: BidiMap

Obtains a MapIterator over the map.

A map iterator is an efficient way of iterating over maps. It does not require that the map is stored using Map Entry objects which can increase performance.

 BidiMap map = new DualHashBidiMap();
 MapIterator it = map.mapIterator();
 while (it.hasNext()) {
   Object key = it.next();
   Object value = it.getValue();
   it.setValue("newValue");
 }
 

Specified by:

mapIterator in interface BidiMap

Specified by:

mapIterator in interface IterableMap

Overrides:

mapIterator in class AbstractBidiMapDecorator

Returns:

a map iterator

inverseBidiMap

public BidiMap inverseBidiMap()

Description copied from interface: BidiMap

Gets a view of this map where the keys and values are reversed.

Changes to one map will be visible in the other and vice versa. This enables both directions of the map to be accessed as a Map.

Implementations should seek to avoid creating a new object every time this method is called. See AbstractMap.values() etc. Calling this method on the inverse map should return the original.

Specified by:

inverseBidiMap in interface BidiMap

Overrides:

inverseBidiMap in class AbstractBidiMapDecorator

Returns:

an inverted bidirectional map