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Java > Open Source Codes > org > netbeans > modules > web > core > jsploader > TimeReference


1 /*
2  * The contents of this file are subject to the terms of the Common Development
3  * and Distribution License (the License). You may not use this file except in
4  * compliance with the License.
5  *
6  * You can obtain a copy of the License at http://www.netbeans.org/cddl.html
7  * or http://www.netbeans.org/cddl.txt.
8  *
9  * When distributing Covered Code, include this CDDL Header Notice in each file
10  * and include the License file at http://www.netbeans.org/cddl.txt.
11  * If applicable, add the following below the CDDL Header, with the fields
12  * enclosed by brackets [] replaced by your own identifying information:
13  * "Portions Copyrighted [year] [name of copyright owner]"
14  *
15  * The Original Software is NetBeans. The Initial Developer of the Original
16  * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
17  * Microsystems, Inc. All Rights Reserved.
18  */
19
20 package org.netbeans.modules.web.core.jsploader;
21
22 /** Reference that holds a value that may expire, because it is outdated.
23  *
24  * @author Petr Jiricka
25  */
26 public class TimeReference {
27
28     private Object JavaDoc value;
29     private long timestamp;
30
31     /** Creates a new instance of TimeBasedCache */
32     public TimeReference() {
33         value = null;
34         timestamp = -1;
35     }
36
37     /** Returns the value, if it is still up to date.
38      * If the value is not set, or if it is out of date, returns null.
39      */
40     public synchronized Object JavaDoc get(long currentTimestamp) {
41         if (currentTimestamp > timestamp) {
42             // out of date
43 value = null;
44         }
45         return value;
46     }
47     
48     /** Puts the given value to the reference,
49      * or updates the value if it already exists. As the
50      * timestamp of the value it uses the supplied long value.
51      */
52     public synchronized void put(Object JavaDoc value, long newTimestamp) {
53         if (newTimestamp > timestamp) {
54             this.timestamp = newTimestamp;
55             this.value = value;
56         }
57     }
58     
59 }
60
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