org.apache.commons.collections.set
Class MapBackedSet

java.lang.Object
  |
  +--org.apache.commons.collections.set.MapBackedSet

All Implemented Interfaces:

Collection, Serializable, Set

public final class MapBackedSet

extends Object

implements Set, 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: 1.2 $ $Date: 2004/06/02 22:00:47 $

Author:

Stephen Colebourne

See Also:

Serialized Form

Field Summary

protected Object	dummyValue The dummyValue to use
protected Map	map The map being used as the backing store

Method Summary

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

Methods inherited from class java.lang.Object

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

Field Detail

map

protected final Map map

The map being used as the backing store

dummyValue

protected final Object dummyValue

The dummyValue to use

Method Detail

decorate

public static Set decorate(Map 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 Set decorate(Map map,
                           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:

IllegalArgumentException - if map is null

size

public int size()

Specified by:

size in interface Set

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Set

iterator

public Iterator iterator()

Specified by:

iterator in interface Set

contains

public boolean contains(Object obj)

Specified by:

contains in interface Set

containsAll

public boolean containsAll(Collection coll)

Specified by:

containsAll in interface Set

add

public boolean add(Object obj)

Specified by:

add in interface Set

addAll

public boolean addAll(Collection coll)

Specified by:

addAll in interface Set

remove

public boolean remove(Object obj)

Specified by:

remove in interface Set

removeAll

public boolean removeAll(Collection coll)

Specified by:

removeAll in interface Set

retainAll

public boolean retainAll(Collection coll)

Specified by:

retainAll in interface Set

clear

public void clear()

Specified by:

clear in interface Set

toArray

public Object[] toArray()

Specified by:

toArray in interface Set

toArray

public Object[] toArray(Object[] array)

Specified by:

toArray in interface Set

equals

public boolean equals(Object obj)

Specified by:

equals in interface Set

Overrides:

equals in class Object

hashCode

public int hashCode()

Specified by:

hashCode in interface Set

Overrides:

hashCode in class Object