001/*
002 *                    BioJava development code
003 *
004 * This code may be freely distributed and modified under the
005 * terms of the GNU Lesser General Public Licence.  This should
006 * be distributed with the code.  If you do not have a copy,
007 * see:
008 *
009 *      http://www.gnu.org/copyleft/lesser.html
010 *
011 * Copyright for this code is held jointly by the individual
012 * authors.  These should be listed in @author doc comments.
013 *
014 * For more information on the BioJava project and its aims,
015 * or to join the biojava-l mailing list, visit the home page
016 * at:
017 *
018 *      http://www.biojava.org/
019 *
020 */
021
022
023package org.biojava.utils.cache;
024
025import java.lang.ref.ReferenceQueue;
026import java.lang.ref.WeakReference;
027
028/**
029 * Subclass of WeakReference which includes and extra field (the key)
030 * which can be used to help cleanup once this reference has been
031 * enqueued.
032 *
033 * @author Thomas Down
034 * @since 1.3
035 */
036
037public class KeyedWeakReference extends WeakReference {
038    private Object key;
039
040    public KeyedWeakReference(Object key, Object ref) {
041        super(ref);
042        this.key = key;
043    }
044
045    public KeyedWeakReference(Object key, Object ref, ReferenceQueue queue) {
046        super(ref, queue);
047        this.key = key;
048    }
049
050    public Object getKey() {
051        return key;
052    }
053}