org.apache.commons.collections.set
Class MapBackedSet

java.lang.Object
  org.apache.commons.collections.set.MapBackedSet

All Implemented Interfaces:

java.io.Serializable, java.lang.Iterable, java.util.Collection, java.util.Set

public final class MapBackedSet
extends java.lang.Object
implements java.util.Set, java.io.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: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $

Author:

Stephen Colebourne

See Also:

Serialized Form

Field Summary

protected java.lang.Object	dummyValue The dummyValue to use
protected java.util.Map	map The map being used as the backing store

Method Summary

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

Methods inherited from class java.lang.Object

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

Field Detail

map

protected final java.util.Map map

The map being used as the backing store

dummyValue

protected final java.lang.Object dummyValue

The dummyValue to use

Method Detail

decorate

public static java.util.Set decorate(java.util.Map map)

Factory method to create a set from a map.

Parameters:

map - the map to decorate, must not be null

Throws:

java.lang.IllegalArgumentException - if set is null

decorate

public static java.util.Set decorate(java.util.Map map,
                                     java.lang.Object 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:

java.lang.IllegalArgumentException - if map is null

size

public int size()

Specified by:

size in interface java.util.Collection

Specified by:

size in interface java.util.Set

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface java.util.Collection

Specified by:

isEmpty in interface java.util.Set

iterator

public java.util.Iterator iterator()

Specified by:

iterator in interface java.lang.Iterable

Specified by:

iterator in interface java.util.Collection

Specified by:

iterator in interface java.util.Set

contains

public boolean contains(java.lang.Object obj)

Specified by:

contains in interface java.util.Collection

Specified by:

contains in interface java.util.Set

containsAll

public boolean containsAll(java.util.Collection coll)

Specified by:

containsAll in interface java.util.Collection

Specified by:

containsAll in interface java.util.Set

add

public boolean add(java.lang.Object obj)

Specified by:

add in interface java.util.Collection

Specified by:

add in interface java.util.Set

addAll

public boolean addAll(java.util.Collection coll)

Specified by:

addAll in interface java.util.Collection

Specified by:

addAll in interface java.util.Set

remove

public boolean remove(java.lang.Object obj)

Specified by:

remove in interface java.util.Collection

Specified by:

remove in interface java.util.Set

removeAll

public boolean removeAll(java.util.Collection coll)

Specified by:

removeAll in interface java.util.Collection

Specified by:

removeAll in interface java.util.Set

retainAll

public boolean retainAll(java.util.Collection coll)

Specified by:

retainAll in interface java.util.Collection

Specified by:

retainAll in interface java.util.Set

clear

public void clear()

Specified by:

clear in interface java.util.Collection

Specified by:

clear in interface java.util.Set

toArray

public java.lang.Object[] toArray()

Specified by:

toArray in interface java.util.Collection

Specified by:

toArray in interface java.util.Set

toArray

public java.lang.Object[] toArray(java.lang.Object[] array)

Specified by:

toArray in interface java.util.Collection

Specified by:

toArray in interface java.util.Set

equals

public boolean equals(java.lang.Object obj)

Specified by:

equals in interface java.util.Collection

Specified by:

equals in interface java.util.Set

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Specified by:

hashCode in interface java.util.Collection

Specified by:

hashCode in interface java.util.Set

Overrides:

hashCode in class java.lang.Object