org.castor.cache.hashbelt.container
Class WeakReferenceContainer

java.lang.Object
  org.castor.cache.hashbelt.container.WeakReferenceContainer

All Implemented Interfaces:

Container, java.util.Map

public final class WeakReferenceContainer

extends java.lang.Object

implements Container

An implementation of a container that uses weak references for storing values in the map, so that values can be removed from the map by the system when the system is under memory pressure. Keys, however, are kept strong - so contains() may well find an element, but the value may have been lost. Make sure you test for null returns from put.

Note that keys are hard references; in a situation where OutOfMemory will occur, the JVM will first wipe out all unreferenced objects whose only link is a weak reference. An out of memory will wipe all values from the maps which are currently unreferenced. The keys remain until the hashbelt containers are garbage collected, an put is called with that key or when the value should be accessed through any operation of the Container interface.

Since:

1.0

Version:

$Revision: 6907 $ $Date: 2006-04-25 16:09:10 -0600 (Tue, 25 Apr 2006) $

Author:

Gregory Block, Ralf Joachim

Nested Class Summary

Nested classes inherited from class java.util.Map

java.util.Map.Entry

Constructor Summary

WeakReferenceContainer()

Method Summary

void	clear()
boolean	containsKey(java.lang.Object key)
boolean	containsValue(java.lang.Object value)
java.util.Set	entrySet()
java.lang.Object	get(java.lang.Object key)
long	getTimestamp() Returns the timestamp of this container.
boolean	isEmpty()
java.util.Iterator	keyIterator() Returns an iterator over the keys contained in this container. If the container is modified while an iteration is in progress, the results of the iteration is not affected and vice-versa.
java.util.Set	keySet()
java.lang.Object	put(java.lang.Object key, java.lang.Object value)
void	putAll(java.util.Map map)
java.lang.Object	remove(java.lang.Object key)
int	size()
void	updateTimestamp() Set the timestamp of this container to System.currentTimeMillis().
java.util.Iterator	valueIterator() Returns an iterator over the values contained in this container. If the container is modified while an iteration is in progress, the results of the iteration is not affected and vice-versa.
java.util.Collection	values()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

equals, hashCode

Constructor Detail

WeakReferenceContainer

public WeakReferenceContainer()

Method Detail

updateTimestamp

public void updateTimestamp()

Set the timestamp of this container to System.currentTimeMillis().

Specified by:

updateTimestamp in interface Container

See Also:

Container.updateTimestamp()

getTimestamp

public long getTimestamp()

Returns the timestamp of this container.

Specified by:

getTimestamp in interface Container

Returns:

The timestamp.

See Also:

Container.getTimestamp()

keyIterator

public java.util.Iterator keyIterator()

Returns an iterator over the keys contained in this container. If the container is modified while an iteration is in progress, the results of the iteration is not affected and vice-versa.

Specified by:

keyIterator in interface Container

Returns:

An iterator over the keys currently contained in the container.

See Also:

Container.keyIterator()

valueIterator

public java.util.Iterator valueIterator()

Returns an iterator over the values contained in this container. If the container is modified while an iteration is in progress, the results of the iteration is not affected and vice-versa.

Specified by:

valueIterator in interface Container

Returns:

An iterator over the values currently contained in the container.

See Also:

Container.valueIterator()

size

public int size()

Specified by:

size in interface java.util.Map

See Also:

Map.size()

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface java.util.Map

See Also:

Map.isEmpty()

containsKey

public boolean containsKey(java.lang.Object key)

Specified by:

containsKey in interface java.util.Map

See Also:

Map.containsKey(java.lang.Object)

containsValue

public boolean containsValue(java.lang.Object value)

Specified by:

containsValue in interface java.util.Map

See Also:

Map.containsValue(java.lang.Object)

get

public java.lang.Object get(java.lang.Object key)

Specified by:

get in interface java.util.Map

See Also:

Map.get(java.lang.Object)

put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object value)

Specified by:

put in interface java.util.Map

See Also:

Map.put(java.lang.Object, java.lang.Object)

remove

public java.lang.Object remove(java.lang.Object key)

Specified by:

remove in interface java.util.Map

See Also:

Map.remove(java.lang.Object)

putAll

public void putAll(java.util.Map map)

Specified by:

putAll in interface java.util.Map

See Also:

Map.putAll(java.util.Map)

clear

public void clear()

Specified by:

clear in interface java.util.Map

See Also:

Map.clear()

keySet

public java.util.Set keySet()

Specified by:

keySet in interface java.util.Map

See Also:

Map.keySet()

values

public java.util.Collection values()

Specified by:

values in interface java.util.Map

See Also:

Map.values()

entrySet

public java.util.Set entrySet()

Specified by:

entrySet in interface java.util.Map

See Also:

Map.entrySet()