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Java > Open Source Codes > org > archive > util > LRU


1 /* LRU
2 *
3 * Created on September 18, 2006
4 *
5 * Copyright (C) 2006 Internet Archive.
6 *
7 * This file is part of the Heritrix web crawler (crawler.archive.org).
8 *
9 * Heritrix is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU Lesser Public License as published by
11 * the Free Software Foundation; either version 2.1 of the License, or
12 * any later version.
13 *
14 * Heritrix is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU Lesser Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser Public License
20 * along with Heritrix; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 */
23 package org.archive.util;
24
25 import java.util.LinkedHashMap JavaDoc;
26 import java.util.Map JavaDoc;
27
28
29 /**
30  * A least-recently used cache. As new entries are added to the map, the
31  * least-recently accessed entries are removed.
32  *
33  * @author pjack
34  *
35  * @param <K> The key type of the LRU
36  * @param <V> The value type of the LRU
37  */
38 public class LRU<K,V> extends LinkedHashMap JavaDoc<K,V> {
39
40
41     /**
42      * Generated by Eclipse.
43      */
44     private static final long serialVersionUID = 1032420936705267913L;
45
46
47     /**
48      * The maximum number of entries to store in the cache.
49      */
50     private int max;
51
52
53     /**
54      * Constructor.
55      *
56      * @param max the maximum number of entries to cache
57      */
58     public LRU(int max) {
59         super(max, (float)0.75, true);
60         this.max = max;
61     }
62     
63     
64     @Override JavaDoc
65     protected boolean removeEldestEntry(Map.Entry JavaDoc<K,V> entry) {
66         return size() >= max;
67     }
68
69 }
70
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