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1 | /*BEGIN_COPYRIGHT_BLOCK | |
2 | * | |
3 | * Copyright (c) 2001-2010, JavaPLT group at Rice University (drjava@rice.edu) | |
4 | * All rights reserved. | |
5 | * | |
6 | * Redistribution and use in source and binary forms, with or without | |
7 | * modification, are permitted provided that the following conditions are met: | |
8 | * * Redistributions of source code must retain the above copyright | |
9 | * notice, this list of conditions and the following disclaimer. | |
10 | * * Redistributions in binary form must reproduce the above copyright | |
11 | * notice, this list of conditions and the following disclaimer in the | |
12 | * documentation and/or other materials provided with the distribution. | |
13 | * * Neither the names of DrJava, the JavaPLT group, Rice University, nor the | |
14 | * names of its contributors may be used to endorse or promote products | |
15 | * derived from this software without specific prior written permission. | |
16 | * | |
17 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
18 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
19 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
20 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR | |
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22 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, | |
23 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR | |
24 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF | |
25 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING | |
26 | * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS | |
27 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
28 | * | |
29 | * This software is Open Source Initiative approved Open Source Software. | |
30 | * Open Source Initative Approved is a trademark of the Open Source Initiative. | |
31 | * | |
32 | * This file is part of DrJava. Download the current version of this project | |
33 | * from http://www.drjava.org/ or http://sourceforge.net/projects/drjava/ | |
34 | * | |
35 | * END_COPYRIGHT_BLOCK*/ | |
36 | ||
37 | package edu.rice.cs.util.swing; | |
38 | ||
39 | import java.awt.EventQueue; | |
40 | ||
41 | /** SwingWorker, adapted from Sun's Java Tutorial. This is the 3rd version of SwingWorker (also known as | |
42 | * SwingWorker 3), an abstract class that you subclass to perform GUI-related work in a dedicated thread. For | |
43 | * instructions on using this class, see: http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html | |
44 | * | |
45 | * Note that the API changed slightly in the 3rd version: you must now invoke start() on the SwingWorker after | |
46 | * creating it. | |
47 | * @version $Id: SwingWorker.java 5175 2010-01-20 08:46:32Z mgricken $ | |
48 | */ | |
49 | public abstract class SwingWorker { | |
50 | private volatile Object _value; // see getValue(), setValue() | |
51 | // private Thread _thread; | |
52 | ||
53 | /** Class to maintain reference to current worker thread under separate synchronization control. */ | |
54 | private static class ThreadVar { | |
55 | private volatile Thread _thread; | |
56 | 0 | ThreadVar(Thread t) { _thread = t; } |
57 | 0 | Thread get() { return _thread; } |
58 | 0 | void clear() { _thread = null; } |
59 | } | |
60 | ||
61 | private volatile ThreadVar _threadVar; | |
62 | ||
63 | /** Gets the value produced by the worker thread, or null if it hasn't been constructed yet. */ | |
64 | 0 | protected Object getValue() { return _value; } |
65 | ||
66 | /** Sets the value produced by worker thread. */ | |
67 | 0 | private void setValue(Object x) { _value = x; } |
68 | ||
69 | /** Compute the value to be returned by the <code>get</code> method. */ | |
70 | public abstract Object construct(); | |
71 | ||
72 | /** Called from the event dispatching thread (not on the worker thread) after the <code>construct</code> method | |
73 | * has returned. | |
74 | */ | |
75 | 0 | public void finished() { } |
76 | ||
77 | /** A new method that interrupts the worker thread. Call this method to force the worker to stop what it's doing. */ | |
78 | 0 | public void interrupt() { |
79 | 0 | Thread t = _threadVar.get(); |
80 | 0 | if (t != null) t.interrupt(); |
81 | 0 | _threadVar.clear(); |
82 | } | |
83 | ||
84 | /** Return the value created by the <code>construct</code> method. Returns null if either the constructing thread | |
85 | * or the current thread was interrupted before a value was produced. | |
86 | * @return the value created by the <code>construct</code> method | |
87 | */ | |
88 | 0 | public Object get() { |
89 | 0 | while (true) { |
90 | 0 | Thread t = _threadVar.get(); |
91 | 0 | if (t == null) return getValue(); |
92 | 0 | try { t.join(); } |
93 | catch (InterruptedException e) { | |
94 | 0 | Thread.currentThread().interrupt(); // propagate |
95 | 0 | return null; |
96 | } | |
97 | } | |
98 | } | |
99 | ||
100 | /** Start a thread that will call the <code>construct</code> method and then exit. */ | |
101 | 0 | public SwingWorker() { |
102 | 0 | final Runnable doFinished = new Runnable() { |
103 | 0 | public void run() { finished(); } |
104 | }; | |
105 | ||
106 | 0 | Runnable doConstruct = new Runnable() { |
107 | 0 | public void run() { |
108 | 0 | try { setValue(construct()); } |
109 | catch (final RuntimeException e) { | |
110 | // Throw the exception in the event dispatching thread. | |
111 | 0 | EventQueue.invokeLater(new Runnable() { public void run() { throw e; } }); |
112 | 0 | throw e; |
113 | } | |
114 | catch (final Error e) { | |
115 | // Throw the error in the event dispatching thread. | |
116 | 0 | EventQueue.invokeLater(new Runnable() { public void run() { throw e; } }); |
117 | 0 | throw e; |
118 | } | |
119 | 0 | finally { _threadVar.clear(); } |
120 | ||
121 | 0 | EventQueue.invokeLater(doFinished); |
122 | } | |
123 | }; | |
124 | ||
125 | 0 | Thread t = new Thread(doConstruct); |
126 | 0 | _threadVar = new ThreadVar(t); |
127 | } | |
128 | ||
129 | /** Start the worker thread. */ | |
130 | 0 | public void start() { |
131 | 0 | Thread t = _threadVar.get(); |
132 | 0 | if (t != null) t.start(); |
133 | } | |
134 | } |
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