Event Listener List : General Event « Event « Java
Event Listener List
/**
* The utillib library.
* More information is available at http://www.jinchess.com/.
* Copyright (C) 2002 Alexander Maryanovsky.
* All rights reserved.
*
* The utillib library is free software; you can redistribute
* it and/or modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* The utillib library is distributed in the hope that it will
* be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
* General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with utillib library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
import java.util.EventListener;
import java.lang.reflect.Array;
/**
* A convenient storage place for Listeners. The listeners are stored in the
* same manner as in javax.swing.event.EventListenerList.
* <STRONG>Note:</STRONG> This class is not thread safe.
*/
public class EventListenerList{
/**
* The array where we keep the listeners and their types.
*/
private Object [] listenerList = new Object[0];
/**
* Adds the given listener as a listener of the given type.
*/
public void add(Class listenerType, EventListener listener){
if (listener==null)
return;
if (!listenerType.isInstance(listener))
throw new IllegalArgumentException("The listener is not an instance of the listener class.");
Object [] tempArr = new Object[listenerList.length+2];
System.arraycopy(listenerList,0,tempArr,0,listenerList.length);
tempArr[tempArr.length-2] = listenerType;
tempArr[tempArr.length-1] = listener;
listenerList = tempArr;
}
/**
* Removes the given listener as a listener of the specified type.
*/
public void remove(Class listenerType, EventListener listener){
if (listener == null)
return;
if (!listenerType.isInstance(listener))
throw new IllegalArgumentException("The listener is not an instance of the listener class.");
for (int i=0;i<listenerList.length;i+=2){
if ((listenerList[i]==listenerType)&&(listenerList[i+1].equals(listener))){
Object [] tempArr = new Object[listenerList.length-2];
System.arraycopy(listenerList,0,tempArr,0,i);
System.arraycopy(listenerList,i+2,tempArr,i,listenerList.length-i-2);
listenerList = tempArr;
return;
}
}
}
/**
* Returns the total number of listeners for this listener list.
*/
public int getListenerCount(){
return listenerList.length;
}
/**
* Returns the amount of listeners of the specified type in this listener
* list.
*/
public int getListenerCount(Class listenerType){
int count = 0;
for (int i=0;i<listenerList.length;i+=2){
if (listenerList[i]==listenerType)
count++;
}
return count;
}
/**
* Returns an array containing all the listeners in this listener list. The
* array contains listeners and their types in the following format: the
* element at index 2*N is the type of the listener at index 2*N+1
* <B>WARNING!!!</B> Absolutely NO modification of the data contained in this array
* should be made -- if any such manipulation is necessary, it should be done on a
* copy of the array returned rather than the array itself.
*/
public Object [] getListenerList(){
return listenerList;
}
/**
* Returns an array of listeners registered as the listeners of the given
* type. Note that the returned array is an array of the actual given type
* so it can be safely casted to that type once instead of casting each of the
* listener.
*/
public EventListener [] getListeners(Class listenerType){
EventListener [] listeners = (EventListener [])Array.newInstance(listenerType,getListenerCount(listenerType));
int count = 0;
for (int i=0;i<listenerList.length;i+=2){
if (listenerType==listenerList[i])
listeners[count++] = (EventListener)listenerList[i+1];
}
return listeners;
}
}
