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Java > Open Source Codes > org > objectweb > jac > util > SharedMap


1 /*
2   Copyright (C) 2001 Laurent Martelli
3
4   This program is free software; you can redistribute it and/or modify
5   it under the terms of the GNU Lesser General Public License as
6   published by the Free Software Foundation; either version 2 of the
7   License, or (at your option) any later version.
8
9   This program is distributed in the hope that it will be useful,
10   but WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12   GNU Lesser General Public License for more details.
13
14   You should have received a copy of the GNU Lesser General Public License
15   along with this program; if not, write to the Free Software
16   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
17
18 package org.objectweb.jac.util;
19
20 import java.util.HashMap JavaDoc;
21
22
23 /**
24  * Implements a map whose data may be shared between several
25  * instances. It has the benefit of having a fast clone() method which
26  * only duplicates the data when needed.
27  */
28 public class SharedMap implements Cloneable JavaDoc {
29    HashMap JavaDoc map;
30    boolean shared=false;
31    public SharedMap() {
32       map = new HashMap JavaDoc();
33    }
34    public SharedMap(HashMap JavaDoc map) {
35       this.map = map;
36    }
37    SharedMap(HashMap JavaDoc map, boolean shared) {
38       this.map = map;
39       this.shared = shared;
40    }
41    public Object JavaDoc clone() {
42       shared = true;
43       return new SharedMap(map,true);
44    }
45    public Object JavaDoc get(Object JavaDoc key) {
46       return map.get(key);
47    }
48    public synchronized void put(Object JavaDoc key, Object JavaDoc value) {
49       if (shared) {
50          //System.out.println("cloning shared map");
51 map = (HashMap JavaDoc)map.clone();
52          shared = false;
53       }
54       map.put(key,value);
55    }
56 }
57
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