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/*******************************************************************************
* Copyright (c) 2001, 2005 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.wst.common.frameworks.internal.ui;
import java.awt.event.ActionListener;
public class ListenerList {
private final static ActionListener[] NULL_ARRAY = new ActionListener[0];
protected transient ActionListener[] listenerList = NULL_ARRAY;
/**
* Add the listener as a listener of the specified type.
*
* @param t
* the type of the listener to be added
* @param l
* the listener to be added
*/
public synchronized void add(ActionListener l) {
if (l == null)
return;
if (listenerList == NULL_ARRAY) {
// if this is the first listener added,
// initialize the lists
listenerList = new ActionListener[]{l};
} else {
// Otherwise copy the array and add the new listener
int i = listenerList.length;
ActionListener[] tmp = new ActionListener[i + 1];
System.arraycopy(listenerList, 0, tmp, 0, i);
tmp[i + 1] = l;
listenerList = tmp;
}
}
/**
* Return the total number of listeners for this listenerlist
*/
public int getListenerCount() {
return listenerList.length;
}
public ActionListener[] getListenerList() {
return listenerList;
}
public synchronized void remove(ActionListener l) {
if (l == null)
return;
int index = -1;
for (int i = listenerList.length - 1; i >= 0; i -= 1) {
if (listenerList[i].equals(l)) {
index = i;
break;
}
}
if (index != -1) {
ActionListener[] tmp = new ActionListener[listenerList.length - 1];
// Copy the list up to index
System.arraycopy(listenerList, 0, tmp, 0, index);
// Copy from two past the index, up to
// the end of tmp (which is two elements
// shorter than the old list)
if (index < tmp.length)
System.arraycopy(listenerList, index + 1, tmp, index, tmp.length - index);
// set the listener array to the new array or null
listenerList = (tmp.length == 0) ? NULL_ARRAY : tmp;
}
}
}
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