org.datanucleus.util

Class WeakValueMap

java.lang.Object

org.datanucleus.util.ReferenceValueMap

org.datanucleus.util.WeakValueMap

All Implemented Interfaces:

Cloneable, Map

public class WeakValueMap
extends ReferenceValueMap

A java.util.Map implementation using weak reference values.

The values are stored in the map as weak references. If the garbage collector clears the reference, the corresponding key is automatically removed from the map.

See Also:

WeakReference

Nested Class Summary

Nested classes/interfaces inherited from class org.datanucleus.util.ReferenceValueMap

ReferenceValueMap.ValueReference

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

Map.Entry<K,V>

Constructor Summary

Constructors

Constructor and Description
WeakValueMap() Default Constructor
WeakValueMap(int initialCapacity) Constructor taking the initial capacity.
WeakValueMap(int initialCapacity, float loadFactor) Constructor taking the initial capacity and load factor.
WeakValueMap(Map m) Constructor taking a Map for definition.

Method Summary

Methods

Modifier and Type	Method and Description
protected ReferenceValueMap.ValueReference	newValueReference(Object key, Object value, ReferenceQueue queue) Returns a new Reference object to be inserted into the map.

Methods inherited from class org.datanucleus.util.ReferenceValueMap

clear, clone, containsKey, containsValue, entrySet, equals, get, hashCode, isEmpty, keySet, put, putAll, reap, remove, size, values

Methods inherited from class java.lang.Object

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

Constructor Detail

WeakValueMap

public WeakValueMap()

Default Constructor

WeakValueMap

public WeakValueMap(int initialCapacity)

Constructor taking the initial capacity.

Parameters:

initialCapacity - The Initial capacity of the collection

WeakValueMap

public WeakValueMap(int initialCapacity,
            float loadFactor)

Constructor taking the initial capacity and load factor.

Parameters:

initialCapacity - The Initial capacity of the collection

loadFactor - The Load Factor of the collection

WeakValueMap

public WeakValueMap(Map m)

Constructor taking a Map for definition.

Parameters:

m - The Map

Method Detail

newValueReference

protected ReferenceValueMap.ValueReference newValueReference(Object key,
                                                 Object value,
                                                 ReferenceQueue queue)

Description copied from class: ReferenceValueMap

Returns a new Reference object to be inserted into the map. Subclasses must implement this method to construct Reference objects of the desired type (e.g. SoftReference, etc.).

Specified by:

newValueReference in class ReferenceValueMap

Parameters:

key - The key that will be inserted.

value - The associated value to be referenced.

queue - The ReferenceQueue with which to register the new Reference object.

Returns:

The new ValueReference