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Java > Open Source Codes > org > apache > activemq > memory > LRUMap


1 /**
2  *
3  * Licensed to the Apache Software Foundation (ASF) under one or more
4  * contributor license agreements. See the NOTICE file distributed with
5  * this work for additional information regarding copyright ownership.
6  * The ASF licenses this file to You under the Apache License, Version 2.0
7  * (the "License"); you may not use this file except in compliance with
8  * the License. You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18 package org.apache.activemq.memory;
19
20 import java.util.LinkedHashMap JavaDoc;
21 import java.util.Map JavaDoc;
22
23 /**
24  * A simple least-recently-used cache of a fixed size.
25  *
26  * @version $Revision:$
27  */
28 public class LRUMap extends LinkedHashMap JavaDoc {
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 LRUMap(int maximumSize) {
37         this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, true, maximumSize);
38     }
39
40     public LRUMap(int maximumSize, boolean accessOrder) {
41         this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, accessOrder, maximumSize);
42     }
43
44     public LRUMap(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 JavaDoc eldest) {
50         return size() > maximumSize;
51     }
52 }
53
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