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Java > Open Source Codes > org > lobobrowser > util > EventDispatch2


1 /*
2     GNU LESSER GENERAL PUBLIC LICENSE
3     Copyright (C) 2006 The Lobo Project
4
5     This library is free software; you can redistribute it and/or
6     modify it under the terms of the GNU Lesser General Public
7     License as published by the Free Software Foundation; either
8     version 2.1 of the License, or (at your option) any later version.
9
10     This library is distributed in the hope that it will be useful,
11     but WITHOUT ANY WARRANTY; without even the implied warranty of
12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13     Lesser General Public License for more details.
14
15     You should have received a copy of the GNU Lesser General Public
16     License along with this library; if not, write to the Free Software
17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18
19     Contact info: xamjadmin@users.sourceforge.net
20 */
21 /*
22  * Created on Mar 19, 2005
23  */
24 package org.lobobrowser.util;
25
26 import java.util.*;
27
28 /**
29  * @author J. H. S.
30  */
31 public abstract class EventDispatch2 {
32     private Collection listeners;
33     private static final EventListener[] EMPTY_ARRAY = new EventListener[0];
34     
35     public EventDispatch2() {
36     }
37     
38     public Collection createListenerCollection() {
39         return new ArrayList();
40     }
41     
42     public final void addListener(EventListener listener) {
43         synchronized(this) {
44             if(this.listeners == null) {
45                 this.listeners = this.createListenerCollection();
46             }
47             this.listeners.add(listener);
48         }
49     }
50     
51     public final void removeListener(EventListener listener) {
52         synchronized(this) {
53             if(this.listeners != null) {
54                 this.listeners.remove(listener);
55             }
56         }
57     }
58     
59     public final boolean fireEvent(EventObject event) {
60         EventListener[] larray;
61         synchronized(this) {
62             Collection listeners = this.listeners;
63             if(listeners == null || listeners.size() == 0) {
64                 return false;
65             }
66             larray = (EventListener[]) this.listeners.toArray(EMPTY_ARRAY);
67         }
68         int length = larray.length;
69         for(int i = 0; i < length; i++) {
70             // Call holding no locks
71 this.dispatchEvent(larray[i], event);
72         }
73         return true;
74     }
75     
76     protected abstract void dispatchEvent(EventListener listener, EventObject event);
77 }
78
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