common
Class WeakHashSet

java.lang.Object
  java.util.AbstractCollection<E>
      java.util.AbstractSet
          common.WeakHashSet

All Implemented Interfaces:

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

public class WeakHashSet
extends java.util.AbstractSet

A HashSet class that uses weak references to its elements. This means that if the only reference to an object is from this set, the object will be garbage-collected and removed from this set. The current implementation is built on WeakHashMap: it's just a map where every key is mapped to Boolean.TRUE. It would be a bit more elegant (and save some memory) to write this class from scratch. But it can't be built on top of an ordinary HashSet, because we want to store WeakReference objects while using the equals and hashCode methods of their referents.

Constructor Summary

WeakHashSet()
Creates a new, empty WeakHashSet.

WeakHashSet(java.util.Collection c)
Creates a new WeakHashSet whose elements are weak references to the elements of the given collection.

Method Summary

boolean	add(java.lang.Object o)
boolean	contains(java.lang.Object o)
java.util.Iterator	iterator()
boolean	remove(java.lang.Object o)
int	size()

Methods inherited from class java.util.AbstractSet

equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection

addAll, clear, containsAll, isEmpty, retainAll, toArray, toArray, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Set

addAll, clear, containsAll, isEmpty, retainAll, toArray, toArray

Constructor Detail

WeakHashSet

public WeakHashSet()

Creates a new, empty WeakHashSet.

WeakHashSet

public WeakHashSet(java.util.Collection c)

Creates a new WeakHashSet whose elements are weak references to the elements of the given collection.

Method Detail

size

public int size()

Specified by:

size in interface java.util.Collection

Specified by:

size in interface java.util.Set

Specified by:

size in class java.util.AbstractCollection

contains

public boolean contains(java.lang.Object o)

Specified by:

contains in interface java.util.Collection

Specified by:

contains in interface java.util.Set

Overrides:

contains in class java.util.AbstractCollection

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

Specified by:

iterator in class java.util.AbstractCollection

add

public boolean add(java.lang.Object o)

Specified by:

add in interface java.util.Collection

Specified by:

add in interface java.util.Set

Overrides:

add in class java.util.AbstractCollection

remove

public boolean remove(java.lang.Object o)

Specified by:

remove in interface java.util.Collection

Specified by:

remove in interface java.util.Set

Overrides:

remove in class java.util.AbstractCollection