1 /**
2  * The utillib library.
3  * More information is available at http://www.jinchess.com/.
4  * Copyright (C) 2002 Alexander Maryanovsky.
5  * All rights reserved.
6  *
7  * The utillib library is free software; you can redistribute
8  * it and/or modify it under the terms of the GNU Lesser General Public License
9  * as published by the Free Software Foundation; either version 2 of the
10  * License, or (at your option) any later version.
11  *
12  * The utillib library is distributed in the hope that it will
13  * be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser
15  * General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public License
18  * along with utillib library; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20  */
21 
22 package free.util;
23 
24 import java.util.EventListener;
25 import java.lang.reflect.Array;
26 
27 
28 /**
29  * A convenient storage place for Listeners. The listeners are stored in the
30  * same manner as in javax.swing.event.EventListenerList.
31  * <STRONG>Note:</STRONG> This class is not thread safe.
32  */
33 
34 public class EventListenerList{
35 
36 
37   /**
38    * The array where we keep the listeners and their types.
39    */
40 
41   private Object [] listenerList = new Object[0];
42 
43 
44 
45   /**
46    * Adds the given listener as a listener of the given type.
47    */
48 
add(Class listenerType, EventListener listener)49   public void add(Class listenerType, EventListener listener){
50     if (listener==null)
51       return;
52     if (!listenerType.isInstance(listener))
53       throw new IllegalArgumentException("The listener is not an instance of the listener class.");
54 
55     Object [] tempArr = new Object[listenerList.length+2];
56     System.arraycopy(listenerList,0,tempArr,0,listenerList.length);
57 
58     tempArr[tempArr.length-2] = listenerType;
59     tempArr[tempArr.length-1] = listener;
60 
61     listenerList = tempArr;
62   }
63 
64 
65 
66 
67   /**
68    * Removes the given listener as a listener of the specified type.
69    */
70 
remove(Class listenerType, EventListener listener)71   public void remove(Class listenerType, EventListener listener){
72     if (listener == null)
73       return;
74     if (!listenerType.isInstance(listener))
75       throw new IllegalArgumentException("The listener is not an instance of the listener class.");
76 
77     for (int i=0;i<listenerList.length;i+=2){
78       if ((listenerList[i]==listenerType)&&(listenerList[i+1].equals(listener))){
79         Object [] tempArr = new Object[listenerList.length-2];
80         System.arraycopy(listenerList,0,tempArr,0,i);
81         System.arraycopy(listenerList,i+2,tempArr,i,listenerList.length-i-2);
82         listenerList = tempArr;
83         return;
84       }
85     }
86   }
87 
88 
89 
90   /**
91    * Returns the total number of listeners for this listener list.
92    */
93 
getListenerCount()94   public int getListenerCount(){
95     return listenerList.length;
96   }
97 
98 
99 
100   /**
101    * Returns the amount of listeners of the specified type in this listener
102    * list.
103    */
104 
getListenerCount(Class listenerType)105   public int getListenerCount(Class listenerType){
106     int count = 0;
107     for (int i=0;i<listenerList.length;i+=2){
108       if (listenerList[i]==listenerType)
109         count++;
110     }
111     return count;
112   }
113 
114 
115 
116   /**
117    * Returns an array containing all the listeners in this listener list. The
118    * array contains listeners and their types in the following format: the
119    * element at index 2*N is the type of the listener at index 2*N+1
120    * <B>WARNING!!!</B> Absolutely NO modification of the data contained in this array
121    * should be made -- if any such manipulation is necessary, it should be done on a
122    * copy of the array returned rather than the array itself.
123    */
124 
getListenerList()125   public Object [] getListenerList(){
126     return listenerList;
127   }
128 
129 
130 
131   /**
132    * Returns an array of listeners registered as the listeners of the given
133    * type. Note that the returned array is an array of the actual given type
134    * so it can be safely casted to that type once instead of casting each of the
135    * listener.
136    */
137 
getListeners(Class listenerType)138   public EventListener [] getListeners(Class listenerType){
139     EventListener [] listeners = (EventListener [])Array.newInstance(listenerType,getListenerCount(listenerType));
140     int count = 0;
141     for (int i=0;i<listenerList.length;i+=2){
142       if (listenerType==listenerList[i])
143         listeners[count++] = (EventListener)listenerList[i+1];
144     }
145     return listeners;
146   }
147 
148 
149 }
150