org.datanucleus.util

Class SoftValueMap

java.lang.Object

org.datanucleus.util.ReferenceValueMap

org.datanucleus.util.SoftValueMap

All Implemented Interfaces:

Cloneable, Map

public class SoftValueMap
extends ReferenceValueMap

A java.util.Map implementation with soft values.

The values are stored as soft references. If map entry value object is not actively being used, i.e. no other object has a strong reference to it, it may become garbage collected at the discretion of the garbage collector (typically if the VM is low on memory). If this happens, the entry in the SoftValueMap corresponding to the value object will also be removed.

See Also:

SoftReference

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

Method Summary

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

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll

Constructor Detail

SoftValueMap

public SoftValueMap()

Default Constructor

SoftValueMap

public SoftValueMap(int initialCapacity)

Constructor taking the initial capacity.

Parameters:

initialCapacity - The Initial capacity of the collection

SoftValueMap

public SoftValueMap(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

SoftValueMap

public SoftValueMap(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