org.apache.commons.collections.set
Class MapBackedSet<K,V>

java.lang.Object
  org.apache.commons.collections.set.MapBackedSet<K,V>

All Implemented Interfaces:

Serializable, Iterable<K>, Collection<K>, Set<K>

public final class MapBackedSet<K,V>
extends Object
implements Set<K>, Serializable

Decorates a Map to obtain Set behaviour.

This class is used to create a Set with the same properties as the key set of any map. Thus, a ReferenceSet can be created by wrapping a ReferenceMap in an instance of this class.

Most map implementation can be used to create a set by passing in dummy values. Exceptions include BidiMap implementations, as they require unique values.

Since:

Commons Collections 3.1

Version:

$Revision: 1.1.1.1 $ $Date: 2005/05/23 04:36:21 $

Author:

Matt Hall, John Watkinson, Stephen Colebourne

See Also:

Serialized Form

Field Summary

protected V	dummyValue The dummyValue to use
protected Map<K,V>	map The map being used as the backing store

Method Summary

boolean	add(K obj)
boolean	addAll(Collection<? extends K> coll)
void	clear()
boolean	contains(Object obj)
boolean	containsAll(Collection<?> coll)
static <K,V> Set<K>	decorate(Map<K,V> map) Factory method to create a set from a map.
static <K,V> Set<K>	decorate(Map<K,V> map, V dummyValue) Factory method to create a set from a map.
boolean	equals(Object obj)
int	hashCode()
boolean	isEmpty()
Iterator<K>	iterator()
boolean	remove(Object obj)
boolean	removeAll(Collection<?> coll)
boolean	retainAll(Collection<?> coll)
int	size()
Object[]	toArray()
<T> T[]	toArray(T[] array)

Methods inherited from class java.lang.Object

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

Field Detail

map

protected final Map<K,V> map

The map being used as the backing store

dummyValue

protected final V dummyValue

The dummyValue to use

Method Detail

decorate

public static <K,V> Set<K> decorate(Map<K,V> map)

Factory method to create a set from a map.

Parameters:

map - the map to decorate, must not be null

Throws:

IllegalArgumentException - if set is null

decorate

public static <K,V> Set<K> decorate(Map<K,V> map,
                                    V dummyValue)

Factory method to create a set from a map.

Parameters:

map - the map to decorate, must not be null

dummyValue - the dummy value to use

Throws:

IllegalArgumentException - if map is null

size

public int size()

Specified by:

size in interface Collection<K>

Specified by:

size in interface Set<K>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Collection<K>

Specified by:

isEmpty in interface Set<K>

iterator

public Iterator<K> iterator()

Specified by:

iterator in interface Iterable<K>

Specified by:

iterator in interface Collection<K>

Specified by:

iterator in interface Set<K>

contains

public boolean contains(Object obj)

Specified by:

contains in interface Collection<K>

Specified by:

contains in interface Set<K>

containsAll

public boolean containsAll(Collection<?> coll)

Specified by:

containsAll in interface Collection<K>

Specified by:

containsAll in interface Set<K>

add

public boolean add(K obj)

Specified by:

add in interface Collection<K>

Specified by:

add in interface Set<K>

addAll

public boolean addAll(Collection<? extends K> coll)

Specified by:

addAll in interface Collection<K>

Specified by:

addAll in interface Set<K>

remove

public boolean remove(Object obj)

Specified by:

remove in interface Collection<K>

Specified by:

remove in interface Set<K>

removeAll

public boolean removeAll(Collection<?> coll)

Specified by:

removeAll in interface Collection<K>

Specified by:

removeAll in interface Set<K>

retainAll

public boolean retainAll(Collection<?> coll)

Specified by:

retainAll in interface Collection<K>

Specified by:

retainAll in interface Set<K>

clear

public void clear()

Specified by:

clear in interface Collection<K>

Specified by:

clear in interface Set<K>

toArray

public Object[] toArray()

Specified by:

toArray in interface Collection<K>

Specified by:

toArray in interface Set<K>

toArray

public <T> T[] toArray(T[] array)

Specified by:

toArray in interface Collection<K>

Specified by:

toArray in interface Set<K>

equals

public boolean equals(Object obj)

Specified by:

equals in interface Collection<K>

Specified by:

equals in interface Set<K>

Overrides:

equals in class Object

hashCode

public int hashCode()

Specified by:

hashCode in interface Collection<K>

Specified by:

hashCode in interface Set<K>

Overrides:

hashCode in class Object