AfflictionNetworks/samskivert
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Allow subclasses to customize the reference.

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git-svn-id: https://samskivert.googlecode.com/svn/trunk@2077 6335cc39-0255-0410-8fd6-9bcaacd3b74c
This commit is contained in:
andrzej
2007-03-22 20:18:30 +00:00
parent 39b92d513f
commit 138f38c502
1 changed files with 16 additions and 8 deletions
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src/java/com/samskivert/util/SoftCache.java
+16 -8
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@@ -1,7 +1,7 @@
// //
// samskivert library - useful routines for java programs // samskivert library - useful routines for java programs
// Copyright (C) 2001-2006 Michael Bayne // Copyright (C) 2001-2006 Michael Bayne
// //
// This library is free software; you can redistribute it and/or modify it // This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published // under the terms of the GNU Lesser General Public License as published
// by the Free Software Foundation; either version 2.1 of the License, or // by the Free Software Foundation; either version 2.1 of the License, or
@@ -23,8 +23,8 @@ import java.util.HashMap;
import java.util.Map; import java.util.Map;
/** /**
* Implements a {@link SoftReference} cache wherein the values in the hashmap * Implements a {@link SoftReference} cache wherein the values in the hashmap are not prevented
* are not prevented from being garbage collected. * from being garbage collected.
*/ */
public class SoftCache<K,V> public class SoftCache<K,V>
{ {
@@ -44,8 +44,7 @@ public class SoftCache<K,V>
} }
/** /**
* Returns true if the supplied key exists in this map and is mapped to an * Returns true if the supplied key exists in this map and is mapped to an active value.
* active value.
*/ */
public boolean containsKey (K key) public boolean containsKey (K key)
{ {
@@ -73,13 +72,13 @@ public class SoftCache<K,V>
*/ */
public V put (K key, V value) public V put (K key, V value)
{ {
SoftReference<V> old = _map.put(key, new SoftReference<V>(value)); SoftReference<V> old = _map.put(key, createReference(value));
return (old == null) ? null : old.get(); return (old == null) ? null : old.get();
} }
/** /**
* Removes the specified key from the map. Returns the value to which the * Removes the specified key from the map. Returns the value to which the key was previously
* key was previously mapped or null. * mapped or null.
*/ */
public V remove (K key) public V remove (K key)
{ {
@@ -95,5 +94,14 @@ public class SoftCache<K,V>
_map.clear(); _map.clear();
} }
/**
* Creates and returns a {@link SoftReference} to the supplied value. Subclasses can override
* to return custom subclasses.
*/
protected SoftReference<V> createReference (V value)
{
return new SoftReference<V>(value);
}
protected HashMap<K,SoftReference<V>> _map; protected HashMap<K,SoftReference<V>> _map;
} }