org.onemind.commons.java.lang.ref
Class SoftHashMap

java.lang.Object
  java.util.AbstractMap
      org.onemind.commons.java.lang.ref.SoftHashMap

All Implemented Interfaces:

java.util.Map

public class SoftHashMap
extends java.util.AbstractMap

Version:

$Id: SoftHashMap.java,v 1.1 2004/10/23 15:24:35 thlee Exp $ $Name: $ Credits: Article by Heinz Kabutz at http://archive.devx.com/java/free/articles/Kabutz01/Kabutz01-1.asp

Author:

TiongHiang Lee (thlee@onemindsoft.org)

Nested Class Summary

private static class

SoftHashMap.SoftValue We define our own subclass of SoftReference which contains not only the value but also the key to make it easier to find the entry in the HashMap after it's been garbage collected.

Nested classes/interfaces inherited from class java.util.AbstractMap

java.util.AbstractMap.SimpleEntry<K,V>, java.util.AbstractMap.SimpleImmutableEntry<K,V>

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

java.util.Map.Entry<K,V>

Field Summary

private int	HARD_REF_SIZE The number of "hard" references to hold internally.
private java.util.LinkedList	hardRefCache The FIFO list of hard references, order of last access.
private java.util.Map	hash The internal HashMap that will hold the SoftReference.
private java.lang.ref.ReferenceQueue	queue Reference queue for cleared SoftReference objects.

Constructor Summary

SoftHashMap()
Constructor

SoftHashMap(int hardSize)
Constructor

Method Summary

private void	_cleanCollectedValues() Go through the ReferenceQueue and remove garbage collected SoftValue objects from the HashMap
void	clear()
java.util.Set	entrySet()
java.lang.Object	get(java.lang.Object key)
java.lang.Object	put(java.lang.Object key, java.lang.Object value) Here we put the key, value pair into the HashMap using a SoftValue object.
java.lang.Object	remove(java.lang.Object key)
int	size()

Methods inherited from class java.util.AbstractMap

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

Methods inherited from class java.lang.Object

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

Field Detail

hash

private final java.util.Map hash

The internal HashMap that will hold the SoftReference.

HARD_REF_SIZE

private final int HARD_REF_SIZE

The number of "hard" references to hold internally.

hardRefCache

private final java.util.LinkedList hardRefCache

The FIFO list of hard references, order of last access.

queue

private final java.lang.ref.ReferenceQueue queue

Reference queue for cleared SoftReference objects.

Constructor Detail

SoftHashMap

public SoftHashMap()

Constructor

SoftHashMap

public SoftHashMap(int hardSize)

Constructor

Parameters:

hardSize - the hard reference size to maintain

Method Detail

get

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

Specified by:

get in interface java.util.Map

Overrides:

get in class java.util.AbstractMap

_cleanCollectedValues

private void _cleanCollectedValues()

Go through the ReferenceQueue and remove garbage collected SoftValue objects from the HashMap

put

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

Here we put the key, value pair into the HashMap using a SoftValue object.

Specified by:

put in interface java.util.Map

Overrides:

put in class java.util.AbstractMap

remove

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

Specified by:

remove in interface java.util.Map

Overrides:

remove in class java.util.AbstractMap

clear

public void clear()

Specified by:

clear in interface java.util.Map

Overrides:

clear in class java.util.AbstractMap

size

public int size()

Specified by:

size in interface java.util.Map

Overrides:

size in class java.util.AbstractMap

entrySet

public java.util.Set entrySet()

Specified by:

entrySet in interface java.util.Map

Specified by:

entrySet in class java.util.AbstractMap