rwth.i2.ltlrv.data
Class WeakValuesHashMap<K,V>

java.lang.Object
  java.util.AbstractMap<K,V>
      rwth.i2.ltlrv.data.WeakValuesHashMap<K,V>

Type Parameters:

K - type parameter for key type

V - type parameter for value type

All Implemented Interfaces:

Serializable, Map<K,V>, WeakValuesMap<K,V>

public class WeakValuesHashMap<K,V>
extends AbstractMap<K,V>
implements WeakValuesMap<K,V>, Serializable

HashMap with weak keys. Bugfixed by Eric Bodden to make equals/hashCode work again. Eric Bodden also added locking.
The implementation is not very efficient, because an entrySet is generated for almost any operation. This is quite expensive.

Author:

Dr. Heinz M. Kabutz, Eric Bodden

See Also:

javaspecialists.co.za, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface rwth.i2.ltlrv.data.WeakValuesMap

WeakValuesMap.Util

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Field Summary

private Map<K,WeakReference<V>>	hash The internal HashMap that will hold the WeakReference.
protected int	hashCode
protected boolean	hashCodeDirty
private boolean	locked If true, this map may not be modified any more.
private ReferenceQueue<V>	queue Reference queue for cleared WeakReference objects.
private Map<WeakReference<V>,K>	reverseLookup
private static long	serialVersionUID Generated SUID.
protected int	size
protected boolean	sizeDirty

Constructor Summary

WeakValuesHashMap()

Method Summary

void	clear()
protected void	dirty() Marks hashCode and size as dirty.
Set<Map.Entry<K,V>>	entrySet() Returns a copy of the key/values in the map at the point of calling.
private void	expungeStaleEntries() Removes stale entries from the map.
V	get(Object key)
int	hashCode()
boolean	isLocked() Returns if this map is locked.
void	lock() Locks the map, so that no modifications are allowed any more.
V	put(K key, V value)
V	remove(Object key)
int	size()
String	toString()

Methods inherited from class java.util.AbstractMap

clone, containsKey, containsValue, equals, isEmpty, keySet, putAll, values

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

containsKey, containsValue, equals, isEmpty, keySet, putAll, values

Field Detail

serialVersionUID

private static final long serialVersionUID

Generated SUID.

See Also:

Constant Field Values

hash

private final Map<K,WeakReference<V>> hash

The internal HashMap that will hold the WeakReference.

reverseLookup

private final Map<WeakReference<V>,K> reverseLookup

queue

private final ReferenceQueue<V> queue

Reference queue for cleared WeakReference objects.

locked

private boolean locked

If true, this map may not be modified any more.

size

protected int size

sizeDirty

protected boolean sizeDirty

hashCode

protected int hashCode

hashCodeDirty

protected boolean hashCodeDirty

Constructor Detail

WeakValuesHashMap

public WeakValuesHashMap()

Method Detail

get

public V get(Object key)

Specified by:

get in interface Map<K,V>

Overrides:

get in class AbstractMap<K,V>

expungeStaleEntries

private void expungeStaleEntries()

Removes stale entries from the map.

put

public V put(K key,
             V value)

Specified by:

put in interface Map<K,V>

Overrides:

put in class AbstractMap<K,V>

remove

public V remove(Object key)

Specified by:

remove in interface Map<K,V>

Overrides:

remove in class AbstractMap<K,V>

clear

public void clear()

Specified by:

clear in interface Map<K,V>

Overrides:

clear in class AbstractMap<K,V>

size

public int size()

Specified by:

size in interface Map<K,V>

Overrides:

size in class AbstractMap<K,V>

lock

public void lock()

Locks the map, so that no modifications are allowed any more. When a modifying method is called, a RuntimeException will be thrown.

Specified by:

lock in interface WeakValuesMap<K,V>

isLocked

public boolean isLocked()

Returns if this map is locked. When it is locked and a modifying method is called, a RuntimeException will be thrown.

Specified by:

isLocked in interface WeakValuesMap<K,V>

Returns:

true if the map is locked

entrySet

public Set<Map.Entry<K,V>> entrySet()

Returns a copy of the key/values in the map at the point of calling. However, setValue still sets the value in the actual WeakValuesHashMap.

Specified by:

entrySet in interface Map<K,V>

Specified by:

entrySet in class AbstractMap<K,V>

Returns:

the entry set

hashCode

public int hashCode()

Specified by:

hashCode in interface Map<K,V>

Overrides:

hashCode in class AbstractMap<K,V>

dirty

protected void dirty()

Marks hashCode and size as dirty.

toString

public String toString()

Overrides:

toString in class AbstractMap<K,V>