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Java > Open Source Codes > net > sf > jasperreports > engine > util > ThreadLocalStack


1 /*
2  * ============================================================================
3  * GNU Lesser General Public License
4  * ============================================================================
5  *
6  * JasperReports - Free Java report-generating library.
7  * Copyright (C) 2001-2006 JasperSoft Corporation http://www.jaspersoft.com
8  *
9  * This library is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * This library 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 GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
22  *
23  * JasperSoft Corporation
24  * 303 Second Street, Suite 450 North
25  * San Francisco, CA 94107
26  * http://www.jaspersoft.com
27  */
28 package net.sf.jasperreports.engine.util;
29
30 import java.util.LinkedList JavaDoc;
31
32
33 /**
34  * Thread local stack utility class.
35  *
36  * @author Lucian Chirita (lucianc@users.sourceforge.net)
37  * @version $Id: ThreadLocalStack.java 1253 2006-05-15 11:12:34 +0300 (Mon, 15 May 2006) lucianc $
38  */
39 public class ThreadLocalStack
40 {
41     private final ThreadLocal JavaDoc threadStack;
42     
43     public ThreadLocalStack()
44     {
45         threadStack = new ThreadLocal JavaDoc();
46     }
47     
48     public void push(Object JavaDoc o)
49     {
50         LinkedList JavaDoc stack = (LinkedList JavaDoc) threadStack.get();
51         if (stack == null)
52         {
53             stack = new LinkedList JavaDoc();
54             threadStack.set(stack);
55         }
56         stack.addFirst(o);
57     }
58     
59     public Object JavaDoc top()
60     {
61         Object JavaDoc o = null;
62         LinkedList JavaDoc stack = (LinkedList JavaDoc) threadStack.get();
63         if (stack != null && !stack.isEmpty())
64         {
65             o = stack.getFirst();
66         }
67         return o;
68     }
69     
70     public Object JavaDoc pop()
71     {
72         Object JavaDoc o = null;
73         LinkedList JavaDoc stack = (LinkedList JavaDoc) threadStack.get();
74         if (stack != null)
75         {
76             o = stack.removeFirst();
77         }
78         return o;
79     }
80     
81     public boolean empty()
82     {
83         LinkedList JavaDoc stack = (LinkedList JavaDoc) threadStack.get();
84         return stack == null || stack.isEmpty();
85     }
86 }
87
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