org.jboss.util.collection
Class WeakSet

java.lang.Object
  java.util.AbstractCollection
      java.util.AbstractSet
          org.jboss.util.collection.WeakSet

All Implemented Interfaces:

Collection, Set

public class WeakSet

extends AbstractSet

implements Set

A Set implementation with weak elements. An entry in a WeakSet will automatically be removed when the element is no longer in ordinary use. More precisely, the presence of an given element will not prevent the element from being discarded by the garbage collector, that is, made finalizable, finalized, and then reclaimed.

Version:

$Revision: 1.1 $

Author:

Jason Dillon

Field Summary

protected ReferenceQueue	queue The reference queue used to get object removal notifications.
protected Set	set The Set which will be used for element storage.

Constructor Summary

WeakSet()
Construct a WeakSet based on a HashSet.

WeakSet(Set set)
Construct a WeakSet.

Method Summary

boolean	add(Object obj) Add an element to the set.
void	clear() Removes all of the elements from this set.
Object	clone() Returns a shallow copy of this WeakSet instance: the elements themselves are not cloned.
boolean	contains(Object obj) Returns true if this set contains the specified element.
boolean	isEmpty() Returns true if this set contains no elements.
Iterator	iterator() Return an iteration over the elements in the set.
protected void	maintain() Maintain the elements in the set.
boolean	remove(Object obj) Removes the given element from this set if it is present.
int	size() Return the size of the set.

Methods inherited from class java.util.AbstractSet

equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection

addAll, containsAll, retainAll, toArray, toArray, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Set

addAll, containsAll, equals, hashCode, removeAll, retainAll, toArray, toArray

Field Detail

queue

protected final ReferenceQueue queue

The reference queue used to get object removal notifications.

set

protected final Set set

The Set which will be used for element storage.

Constructor Detail

WeakSet

public WeakSet(Set set)

Construct a WeakSet. Any elements in the given set will be wrapped in WeakObject references.

Parameters:

set - The Set which will be used for element storage.

Throws:

NullArgumentException - Set is null.

WeakSet

public WeakSet()

Construct a WeakSet based on a HashSet.

Method Detail

maintain

protected final void maintain()

Maintain the elements in the set. Removes objects from the set that have been reclaimed due to GC.

size

public int size()

Return the size of the set.

Specified by:

size in interface Set

Returns:

The size of the set.

iterator

public Iterator iterator()

Return an iteration over the elements in the set.

Specified by:

iterator in interface Set

Returns:

An iteration over the elements in the set.

add

public boolean add(Object obj)

Add an element to the set.

Specified by:

add in interface Set

Parameters:

obj - Element to add to the set.

Returns:

True if the element was added.

isEmpty

public boolean isEmpty()

Returns true if this set contains no elements.

Specified by:

isEmpty in interface Set

Returns:

true if this set contains no elements.

contains

public boolean contains(Object obj)

Returns true if this set contains the specified element.

Specified by:

contains in interface Set

Parameters:

obj - Element whose presence in this set is to be tested.

Returns:

true if this set contains the specified element.

remove

public boolean remove(Object obj)

Removes the given element from this set if it is present.

Specified by:

remove in interface Set

Parameters:

obj - Object to be removed from this set, if present.

Returns:

true if the set contained the specified element.

clear

public void clear()

Removes all of the elements from this set.

Specified by:

clear in interface Set

clone

public Object clone()

Returns a shallow copy of this WeakSet instance: the elements themselves are not cloned.

Returns:

A shallow copy of this set.