1 /***
2 *
3 * Copyright 2005 LogicBlaze, Inc. http://www.logicblaze.com
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 **/
18 package org.logicblaze.lingo.util;
19
20 import java.util.LinkedHashMap;
21 import java.util.Map;
22
23 /***
24 * A simple least-recently-used cache of a fixed size.
25 *
26 * @version $Revision$
27 */
28 public class LRUCache extends LinkedHashMap {
29 private static final long serialVersionUID = -9179676638408888162L;
30
31 protected static final float DEFAULT_LOAD_FACTOR = (float) 0.75;
32 protected static final int DEFAULT_INITIAL_CAPACITY = 5000;
33
34 private int maximumSize;
35
36 public LRUCache(int maximumSize) {
37 this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, true, maximumSize);
38 }
39
40 public LRUCache(int maximumSize, boolean accessOrder) {
41 this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, accessOrder, maximumSize);
42 }
43
44 public LRUCache(int initialCapacity, float loadFactor, boolean accessOrder, int maximumSize) {
45 super(initialCapacity, loadFactor, accessOrder);
46 this.maximumSize = maximumSize;
47 }
48
49 protected boolean removeEldestEntry(Map.Entry eldest) {
50 return size() > maximumSize;
51 }
52 }