org.apache.commons.collections.bidimap
Class UnmodifiableBidiMap<K,V>

java.lang.Object
  org.apache.commons.collections.map.AbstractMapDecorator<K,V>
      org.apache.commons.collections.bidimap.AbstractBidiMapDecorator<K,V>
          org.apache.commons.collections.bidimap.UnmodifiableBidiMap<K,V>

All Implemented Interfaces:

Map<K,V>, BidiMap<K,V>, IterableMap<K,V>, Unmodifiable

public final class UnmodifiableBidiMap<K,V>
extends AbstractBidiMapDecorator<K,V>
implements Unmodifiable

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

Since:

Commons Collections 3.0

Version:

$Revision: 1.1.1.1 $ $Date: 2005/05/23 04:33:47 $

Author:

Matt Hall, John Watkinson, Stephen Colebourne

Nested Class Summary

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

Map.Entry<K,V>

Field Summary

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

map

Method Summary

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

IllegalArgumentException - if map is null

clear

public void clear()

Specified by:

clear in interface Map<K,V>

Overrides:

clear in class AbstractMapDecorator<K,V>

put

public V put(K key,
             V 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 Map<K,V>

Specified by:

put in interface BidiMap<K,V>

Overrides:

put in class AbstractMapDecorator<K,V>

Parameters:

key - the key to store

value - the value to store

Returns:

the previous value mapped to this key

putAll

public void putAll(Map<? extends K,? extends V> mapToCopy)

Specified by:

putAll in interface Map<K,V>

Overrides:

putAll in class AbstractMapDecorator<K,V>

remove

public V remove(Object key)

Specified by:

remove in interface Map<K,V>

Overrides:

remove in class AbstractMapDecorator<K,V>

entrySet

public Set<Map.Entry<K,V>> entrySet()

Specified by:

entrySet in interface Map<K,V>

Overrides:

entrySet in class AbstractMapDecorator<K,V>

keySet

public Set<K> keySet()

Specified by:

keySet in interface Map<K,V>

Overrides:

keySet in class AbstractMapDecorator<K,V>

values

public Collection<V> values()

Specified by:

values in interface Map<K,V>

Overrides:

values in class AbstractMapDecorator<K,V>

removeValue

public K removeValue(V 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<K,V>

Overrides:

removeValue in class AbstractBidiMapDecorator<K,V>

Parameters:

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

Returns:

the key that was removed, null if nothing removed

mapIterator

public MapIterator<K,V> 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<K,V>

Specified by:

mapIterator in interface IterableMap<K,V>

Overrides:

mapIterator in class AbstractBidiMapDecorator<K,V>

Returns:

a map iterator

inverseBidiMap

public BidiMap<V,K> 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<K,V>

Overrides:

inverseBidiMap in class AbstractBidiMapDecorator<K,V>

Returns:

an inverted bidirectional map