org.cojen.util
Class WeakIdentityMap<K,V>

java.lang.Object
  java.util.AbstractMap<K,V>
      org.cojen.util.WeakIdentityMap<K,V>

All Implemented Interfaces:

Cloneable, Map<K,V>

public class WeakIdentityMap<K,V>
extends AbstractMap<K,V>
implements Map<K,V>, Cloneable

WeakIdentityMap is like WeakHashMap, except it uses a key's identity hashcode and equals methods. WeakIdentityMap is not thread-safe and must be wrapped with Collections.synchronizedMap to be made thread-safe.

The documentation for WeakHashMap states that it is intended primarily for use with key objects whose equals methods test for object identity using the == operator. Because WeakIdentityMap strictly follows this behavior, it is better suited for this purpose.

Note: Weakly referenced entries may be automatically removed during either accessor or mutator operations, possibly causing a concurrent modification to be detected. Therefore, even if multiple threads are only accessing this map, be sure to synchronize this map first. Also, do not rely on the value returned by size() when using an iterator from this map. The iterators may return less entries than the amount reported by size().

Author:

Brian S O'Neill

Constructor Summary

WeakIdentityMap()

WeakIdentityMap(int initialCapacity)

WeakIdentityMap(int initialCapacity, float loadFactor)

WeakIdentityMap(Map<? extends K,? extends V> t)

Method Summary

void	clear()
Object	clone()
boolean	containsKey(Object key)
boolean	containsValue(Object value)
Set<Map.Entry<K,V>>	entrySet()
V	get(Object key)
boolean	isEmpty()
Set<K>	keySet()
V	put(K key, V value)
void	putAll(Map<? extends K,? extends V> t)
V	remove(Object key)
int	size()
String	toString() Gets the map as a String.
Collection<V>	values()

Methods inherited from class java.util.AbstractMap

equals, hashCode

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

equals, hashCode

Constructor Detail

WeakIdentityMap

public WeakIdentityMap(int initialCapacity,
                       float loadFactor)

WeakIdentityMap

public WeakIdentityMap(int initialCapacity)

WeakIdentityMap

public WeakIdentityMap()

WeakIdentityMap

public WeakIdentityMap(Map<? extends K,? extends V> t)

Method Detail

size

public int size()

Specified by:

size in interface Map<K,V>

Overrides:

size in class AbstractMap<K,V>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<K,V>

Overrides:

isEmpty in class AbstractMap<K,V>

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map<K,V>

Overrides:

containsValue in class AbstractMap<K,V>

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map<K,V>

Overrides:

containsKey in class AbstractMap<K,V>

get

public V get(Object key)

Specified by:

get in interface Map<K,V>

Overrides:

get in class AbstractMap<K,V>

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>

putAll

public void putAll(Map<? extends K,? extends V> t)

Specified by:

putAll in interface Map<K,V>

Overrides:

putAll in class AbstractMap<K,V>

clear

public void clear()

Specified by:

clear in interface Map<K,V>

Overrides:

clear in class AbstractMap<K,V>

clone

public Object clone()

Overrides:

clone in class AbstractMap<K,V>

keySet

public Set<K> keySet()

Specified by:

keySet in interface Map<K,V>

Overrides:

keySet in class AbstractMap<K,V>

values

public Collection<V> values()

Specified by:

values in interface Map<K,V>

Overrides:

values in class AbstractMap<K,V>

entrySet

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

Specified by:

entrySet in interface Map<K,V>

Specified by:

entrySet in class AbstractMap<K,V>

toString

public String toString()

Gets the map as a String.

Overrides:

toString in class AbstractMap<K,V>

Returns:

a string version of the map