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56 package org.objectstyle.cayenne.dataview;
57
58 import java.util.ArrayList  ;
59 import java.util.EventListener ;
60
61 public class EventDispatcher {
62 protected transient ArrayList listeners = new ArrayList (1);
63
64 public void dispatch(DispatchableEvent e) {
65 EventListener [] listenersCopy = null;
66 synchronized(this) {
67 if (hasListeners())
68 listenersCopy = (EventListener [])listeners.toArray(new EventListener [listeners.size()]);
69 }
70
71 if (listenersCopy != null) {
72 int count = listenersCopy.length;
73 for (int index = 0; index < count; ++index) {
74 e.dispatch(listenersCopy[index]);
75 }
76 }
77 }
78
79 public synchronized boolean hasListeners() {
80 return !listeners.isEmpty();
81 }
82
83 public synchronized int getListenerCount() {
84 return listeners.size();
85 }
86
87 public synchronized int find(EventListener listener) {
88 return listeners.indexOf(listener);
89 }
90
91 public synchronized void add(EventListener listener) {
92 if (find(listener) < 0)
93 listeners.add(listener);
94 }
95
96 public synchronized void remove(EventListener listener) {
97 listeners.remove(listener);
98 }
99
100 public synchronized void clear() {
101 listeners.clear();
102 }
103
104 public static EventDispatcher add(EventDispatcher dispatcher, EventListener listener) {
105 if (dispatcher == null)
106 dispatcher = new EventDispatcher();
107 dispatcher.add(listener);
108 return dispatcher;
109 }
110
111 public final static EventDispatcher remove(EventDispatcher dispatcher, EventListener listener) {
112 if (dispatcher != null) {
113 dispatcher.remove(listener);
114 if (!dispatcher.hasListeners())
115 dispatcher = null;
116 }
117 return dispatcher;
118 }
119 }
120 |
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