Classes in this File | Line Coverage | Branch Coverage | Complexity | |||||||
EODelayedObserver |
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1 | /* |
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2 | Wotonomy: OpenStep design patterns for pure Java applications. |
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3 | Copyright (C) 2000 Intersect Software Corporation |
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4 | ||
5 | This library is free software; you can redistribute it and/or |
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6 | modify it under the terms of the GNU Lesser General Public |
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7 | License as published by the Free Software Foundation; either |
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8 | version 2.1 of the License, or (at your option) any later version. |
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9 | ||
10 | This library is distributed in the hope that it will be useful, |
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11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 | Lesser General Public License for more details. |
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14 | ||
15 | You should have received a copy of the GNU Lesser General Public |
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16 | License along with this library; if not, see http://www.gnu.org |
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17 | */ |
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18 | ||
19 | package net.wotonomy.control; |
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20 | ||
21 | import java.util.Observable; |
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22 | import java.util.Observer; |
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23 | ||
24 | /** |
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25 | * This is an abstract class for receiving coalesced |
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26 | * notifications of changes from objects. |
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27 | * This class also implements Observer for greater |
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28 | * compatibility. |
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29 | * The point of EODelayedObservers is that when |
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30 | * they receive a willChange message, they |
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31 | * queue themselves with a EODelayedObserverQueue |
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32 | * so they can receive a single subjectChanged() |
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33 | * after all changes from an observed object take |
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34 | * place. |
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35 | * |
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36 | * @author michael@mpowers.net |
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37 | * @author $Author: cgruber $ |
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38 | * @version $Revision: 894 $ |
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39 | */ |
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40 | public abstract class EODelayedObserver |
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41 | implements EOObserving, Observer |
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42 | { |
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43 | /** |
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44 | * Notified immediately. |
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45 | */ |
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46 | public static final int ObserverPriorityImmediate = 0; |
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47 | public static final int ObserverPriorityFirst = 1; |
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48 | public static final int ObserverPrioritySecond = 2; |
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49 | public static final int ObserverPriorityThird = 3; |
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50 | public static final int ObserverPriorityFourth = 4; |
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51 | public static final int ObserverPriorityFifth = 5; |
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52 | public static final int ObserverPrioritySixth = 6; |
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53 | public static final int ObserverPriorityLater = 7; |
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54 | public static final int ObserverNumberOfPriorities = 8; |
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55 | ||
56 | /** |
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57 | * Default constructor. |
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58 | */ |
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59 | 0 | public EODelayedObserver () |
60 | 0 | { |
61 | 0 | } |
62 | ||
63 | /** |
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64 | * Removes this observer from the observer queue |
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65 | * for a currently pending notification. |
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66 | */ |
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67 | public void discardPendingNotification () |
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68 | { |
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69 | 0 | observerQueue().dequeueObserver( this ); |
70 | 0 | } |
71 | ||
72 | /** |
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73 | * Returns the observer queue to which this observer |
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74 | * belongs. This implementation returns the default |
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75 | * EODelayedObserverQueue. |
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76 | * Override to use a different one. |
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77 | */ |
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78 | public EODelayedObserverQueue observerQueue () |
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79 | { |
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80 | 0 | return EODelayedObserverQueue.defaultObserverQueue(); |
81 | } |
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82 | ||
83 | /** |
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84 | * Returns the priority of this observer in the queue. |
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85 | * This implementation returns ObserverPriorityThird. |
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86 | * Override to be notified before other observers. |
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87 | */ |
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88 | public int priority () |
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89 | { |
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90 | 0 | return ObserverPriorityThird; |
91 | } |
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92 | ||
93 | /** |
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94 | * Notifies observer that one or more objects that |
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95 | * it is observing have changed. The observer should |
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96 | * check all objects it is observing for changes. |
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97 | */ |
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98 | public abstract void subjectChanged (); |
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99 | ||
100 | // interface EOObserving |
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101 | ||
102 | /** |
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103 | * Called when the specified object is about to change. |
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104 | * This implementation puts this observer on a |
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105 | * notification queue. |
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106 | */ |
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107 | public void objectWillChange ( Object anObject ) |
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108 | { |
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109 | 0 | observerQueue().enqueueObserver( this ); |
110 | 0 | } |
111 | ||
112 | // interface Observer |
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113 | ||
114 | /** |
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115 | * Called when the specified object has changed, |
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116 | * with the specified argument. |
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117 | * This method is included for interacting with |
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118 | * the java.lang.Observer pattern. |
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119 | * This implementation simply objectWillChange(anObject) |
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120 | * so that the observer still gets a single subjectChanged |
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121 | * call in response to multiple changes. |
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122 | */ |
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123 | public void update ( Observable anObject, Object aValue ) |
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124 | { |
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125 | 0 | objectWillChange( anObject ); |
126 | 0 | } |
127 | ||
128 | } |
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129 | ||
130 | /* |
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131 | * $Log$ |
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132 | * Revision 1.2 2006/02/16 16:47:14 cgruber |
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133 | * Move some classes in to "internal" packages and re-work imports, etc. |
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134 | * |
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135 | * Also use UnsupportedOperationExceptions where appropriate, instead of WotonomyExceptions. |
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136 | * |
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137 | * Revision 1.1 2006/02/16 13:19:57 cgruber |
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138 | * Check in all sources in eclipse-friendly maven-enabled packages. |
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139 | * |
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140 | * Revision 1.2 2001/10/26 18:38:10 mpowers |
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141 | * Reordered priorities. |
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142 | * |
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143 | * Revision 1.1.1.1 2000/12/21 15:46:38 mpowers |
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144 | * Contributing wotonomy. |
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145 | * |
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146 | * Revision 1.3 2000/12/20 16:25:35 michael |
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147 | * Added log to all files. |
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148 | * |
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149 | * |
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150 | */ |
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151 | ||
152 |