1 | //////////////////////////////////////////////////////////////////////// |
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2 | // |
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3 | // This file SwingWorker.java is part of SURFEX. |
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4 | // |
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5 | //////////////////////////////////////////////////////////////////////// |
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6 | |
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7 | //////////////////////////////////////////////////////////////////////// |
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8 | // |
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9 | // SURFEX version 0.90.00 |
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10 | // ================= |
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11 | // |
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12 | // Saarland University at Saarbruecken, Germany |
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13 | // Department of Mathematics and Computer Science |
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14 | // |
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15 | // SURFEX on the web: www.surfex.AlgebraicSurface.net |
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16 | // |
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17 | // Authors: Oliver Labs (2001-2008), Stephan Holzer (2004-2005) |
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18 | // |
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19 | // Copyright (C) 2001-2008 |
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20 | // |
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21 | // |
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22 | // *NOTICE* |
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23 | // ======== |
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24 | // |
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25 | // This program is free software; you can redistribute it and/or modify it |
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26 | // under the terms of the GNU General Public License as published by the |
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27 | // Free Software Foundation ( version 3 or later of the License ). |
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28 | // |
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29 | // See LICENCE.TXT for details. |
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30 | // |
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31 | ///////////////////////////////////////////////////////////////////////// |
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32 | |
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33 | import javax.swing.SwingUtilities; |
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34 | |
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35 | /** |
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36 | * This file is an adaption of the following: |
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37 | * |
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38 | * This is the 3rd version of SwingWorker (also known as |
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39 | * SwingWorker 3), an abstract class that you subclass to |
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40 | * perform GUI-related work in a dedicated thread. For |
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41 | * instructions on and examples of using this class, see: |
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42 | * |
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43 | * http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html |
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44 | * |
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45 | * Note that the API changed slightly in the 3rd version: |
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46 | * You must now invoke start() on the SwingWorker after |
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47 | * creating it. |
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48 | */ |
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49 | public abstract class SwingWorker { |
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50 | private Object value; // see getValue(), setValue() |
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51 | |
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52 | /** |
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53 | * Class to maintain reference to current worker thread |
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54 | * under separate synchronization control. |
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55 | */ |
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56 | private static class ThreadVar { |
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57 | private Thread thread; |
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58 | ThreadVar(Thread t) { thread = t; } |
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59 | synchronized Thread get() { return thread; } |
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60 | synchronized void clear() { thread = null; } |
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61 | } |
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62 | |
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63 | private ThreadVar threadVar; |
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64 | |
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65 | /** |
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66 | * Get the value produced by the worker thread, or null if it |
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67 | * hasn't been constructed yet. |
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68 | */ |
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69 | protected synchronized Object getValue() { |
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70 | return value; |
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71 | } |
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72 | |
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73 | /** |
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74 | * Set the value produced by worker thread |
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75 | */ |
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76 | private synchronized void setValue(Object x) { |
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77 | value = x; |
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78 | } |
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79 | |
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80 | /** |
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81 | * Compute the value to be returned by the <code>get</code> method. |
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82 | */ |
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83 | public abstract Object construct(); |
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84 | |
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85 | /** |
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86 | * Called on the event dispatching thread (not on the worker thread) |
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87 | * after the <code>construct</code> method has returned. |
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88 | */ |
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89 | public void finished() { |
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90 | } |
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91 | |
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92 | /** |
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93 | * A new method that interrupts the worker thread. Call this method |
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94 | * to force the worker to stop what it's doing. |
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95 | */ |
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96 | public void interrupt() { |
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97 | Thread t = threadVar.get(); |
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98 | if (t != null) { |
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99 | t.interrupt(); |
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100 | } |
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101 | threadVar.clear(); |
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102 | } |
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103 | |
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104 | /** |
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105 | * Return the value created by the <code>construct</code> method. |
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106 | * Returns null if either the constructing thread or the current |
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107 | * thread was interrupted before a value was produced. |
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108 | * |
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109 | * @return the value created by the <code>construct</code> method |
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110 | */ |
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111 | public Object get() { |
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112 | while (true) { |
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113 | Thread t = threadVar.get(); |
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114 | if (t == null) { |
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115 | return getValue(); |
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116 | } |
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117 | try { |
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118 | t.join(); |
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119 | } |
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120 | catch (InterruptedException e) { |
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121 | Thread.currentThread().interrupt(); // propagate |
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122 | return null; |
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123 | } |
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124 | } |
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125 | } |
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126 | |
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127 | |
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128 | /** |
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129 | * Start a thread that will call the <code>construct</code> method |
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130 | * and then exit. |
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131 | */ |
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132 | public SwingWorker() { |
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133 | final Runnable doFinished = new Runnable() { |
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134 | public void run() { finished(); } |
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135 | }; |
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136 | |
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137 | Runnable doConstruct = new Runnable() { |
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138 | public void run() { |
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139 | try { |
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140 | setValue(construct()); |
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141 | } |
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142 | finally { |
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143 | threadVar.clear(); |
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144 | } |
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145 | |
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146 | SwingUtilities.invokeLater(doFinished); |
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147 | } |
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148 | }; |
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149 | |
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150 | Thread t = new Thread(doConstruct); |
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151 | threadVar = new ThreadVar(t); |
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152 | } |
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153 | |
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154 | /** |
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155 | * Start the worker thread. |
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156 | */ |
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157 | public void start() { |
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158 | Thread t = threadVar.get(); |
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159 | if (t != null) { |
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160 | t.start(); |
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161 | } |
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162 | } |
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163 | } |
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164 | |
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