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	/*
	* Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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 General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package sun.awt;

	import java.lang.reflect.Array;
	import java.util.EventListener;


	/**
	* A class that assists in managing {@link java.util.EventListener}s of
	* the specified type. Its instance holds an array of listeners of the same
	* type and allows to perform the typical operations on the listeners.
	* This class is thread-safe.
	*
	* @author Alexander Gerasimov
	*
	* @since 1.5
	*/
	public class EventListenerAggregate {

	private EventListener[] listenerList;

	/**
	* Constructs an <code>EventListenerAggregate</code> object.
	*
	* @param listenerClass the type of the listeners to be managed by this object
	*
	* @throws NullPointerException if <code>listenerClass</code> is
	* <code>null</code>
	* @throws ClassCastException if <code>listenerClass</code> is not
	* assignable to <code>java.util.EventListener</code>
	*/
	public EventListenerAggregate(Class<? extends EventListener> listenerClass) {
	if (listenerClass == null) {
	throw new NullPointerException("listener class is null");
	}

	listenerList = (EventListener[])Array.newInstance(listenerClass, 0);
	}

	private Class<?> getListenerClass() {
	return listenerList.getClass().getComponentType();
	}

	/**
	* Adds the listener to this aggregate.
	*
	* @param listener the listener to be added
	*
	* @throws ClassCastException if <code>listener</code> is not
	* an instatce of <code>listenerClass</code> specified
	* in the constructor
	*/
	public synchronized void add(EventListener listener) {
	Class<?> listenerClass = getListenerClass();

	if (!listenerClass.isInstance(listener)) { // null is not an instance of any class
	throw new ClassCastException("listener " + listener + " is not " +
	"an instance of listener class " + listenerClass);
	}

	EventListener[] tmp = (EventListener[])Array.newInstance(listenerClass, listenerList.length + 1);
	System.arraycopy(listenerList, 0, tmp, 0, listenerList.length);
	tmp[listenerList.length] = listener;
	listenerList = tmp;
	}

	/**
	* Removes a listener that is equal to the given one from this aggregate.
	* <code>equals()</code> method is used to compare listeners.
	*
	* @param listener the listener to be removed
	*
	* @return <code>true</code> if this aggregate contained the specified
	* <code>listener</code>; <code>false</code> otherwise
	*
	* @throws ClassCastException if <code>listener</code> is not
	* an instatce of <code>listenerClass</code> specified
	* in the constructor
	*/
	public synchronized boolean remove(EventListener listener) {
	Class<?> listenerClass = getListenerClass();

	if (!listenerClass.isInstance(listener)) { // null is not an instance of any class
	throw new ClassCastException("listener " + listener + " is not " +
	"an instance of listener class " + listenerClass);
	}

	for (int i = 0; i < listenerList.length; i++) {
	if (listenerList[i].equals(listener)) {
	EventListener[] tmp = (EventListener[])Array.newInstance(listenerClass,
	listenerList.length - 1);
	System.arraycopy(listenerList, 0, tmp, 0, i);
	System.arraycopy(listenerList, i + 1, tmp, i, listenerList.length - i - 1);
	listenerList = tmp;

	return true;
	}
	}

	return false;
	}

	/**
	* Returns an array of all the listeners contained in this aggregate.
	* The array is the data structure in which listeners are stored internally.
	* The runtime type of the returned array is "array of <code>listenerClass</code>"
	* (<code>listenerClass</code> has been specified as a parameter to
	* the constructor of this class).
	*
	* @return all the listeners contained in this aggregate (an empty
	* array if there are no listeners)
	*/
	public synchronized EventListener[] getListenersInternal() {
	return listenerList;
	}

	/**
	* Returns an array of all the listeners contained in this aggregate.
	* The array is a copy of the data structure in which listeners are stored
	* internally.
	* The runtime type of the returned array is "array of <code>listenerClass</code>"
	* (<code>listenerClass</code> has been specified as a parameter to
	* the constructor of this class).
	*
	* @return a copy of all the listeners contained in this aggregate (an empty
	* array if there are no listeners)
	*/
	public synchronized EventListener[] getListenersCopy() {
	return (listenerList.length == 0) ? listenerList : listenerList.clone();
	}

	/**
	* Returns the number of lisetners in this aggregate.
	*
	* @return the number of lisetners in this aggregate
	*/
	public synchronized int size() {
	return listenerList.length;
	}

	/**
	* Returns <code>true</code> if this aggregate contains no listeners,
	* <code>false</code> otherwise.
	*
	* @return <code>true</code> if this aggregate contains no listeners,
	* <code>false</code> otherwise
	*/
	public synchronized boolean isEmpty() {
	return listenerList.length == 0;
	}
	}

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