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	/*
	* Copyright (c) 2005, 2015, 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 com.sun.java.accessibility.util;

	import java.util.*;
	import java.beans.*;
	import java.awt.*;
	import java.awt.event.*;
	import javax.accessibility.*;

	/**
	* <P>The {@code AccessibilityListenerList} is a copy of the Swing
	* {@link javax.swing.event.EventListenerList EventListerList} class.
	*
	*/

	@jdk.Exported
	public class AccessibilityListenerList {
	/* A null array to be shared by all empty listener lists */
	private final static Object[] NULL_ARRAY = new Object[0];

	/**
	* The list of listener type, listener pairs
	*/
	protected transient Object[] listenerList = NULL_ARRAY;

	/**
	* Passes back the event listener list as an array of listener type, listener pairs.
	* Note that for performance reasons, this implementation passes back the actual
	* data structure in which the listener data is stored internally. This method
	* is guaranteed to pass back a non-null array, so that no null-checking
	* is required in fire methods. A zero-length array of Object is returned if
	* there are currently no listeners.
	* <p>
	* 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.
	*
	* @return an array of listener type, listener pairs.
	*/
	public Object[] getListenerList() {
	return listenerList;
	}

	/**
	* Returns the total number of listeners for this listener list.
	*
	* @return the total number of listeners for this listener list.
	*/
	public int getListenerCount() {
	return listenerList.length/2;
	}

	/**
	* Return the total number of listeners of the supplied type
	* for this listener list.
	*
	* @param t the type of the listener to be counted
	* @return the number of listeners found
	*/
	public int getListenerCount(Class t) {
	int count = 0;
	Object[] lList = listenerList;
	for (int i = 0; i < lList.length; i+=2) {
	if (t == (Class)lList[i])
	count++;
	}
	return count;
	}

	/**
	* 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(Class t, EventListener l) {
	if (!t.isInstance(l)) {
	throw new IllegalArgumentException("Listener " + l +
	" is not of type " + t);
	}
	if (l ==null) {
	throw new IllegalArgumentException("Listener " + l +
	" is null");
	}
	if (listenerList == NULL_ARRAY) {
	// if this is the first listener added,
	// initialize the lists
	listenerList = new Object[] { t, l };
	} else {
	// Otherwise copy the array and add the new listener
	int i = listenerList.length;
	Object[] tmp = new Object[i+2];
	System.arraycopy(listenerList, 0, tmp, 0, i);

	tmp[i] = t;
	tmp[i+1] = l;

	listenerList = tmp;
	}
	}

	/**
	* Remove the listener as a listener of the specified type.
	*
	* @param t the type of the listener to be removed
	* @param l the listener to be removed
	*/
	public synchronized void remove(Class t, EventListener l) {
	if (!t.isInstance(l)) {
	throw new IllegalArgumentException("Listener " + l +
	" is not of type " + t);
	}
	if (l ==null) {
	throw new IllegalArgumentException("Listener " + l +
	" is null");
	}

	// Is l on the list?
	int index = -1;
	for (int i = listenerList.length-2; i>=0; i-=2) {
	if ((listenerList[i]==t) && (listenerList[i+1] == l)) {
	index = i;
	break;
	}
	}

	// If so, remove it
	if (index != -1) {
	Object[] tmp = new Object[listenerList.length-2];
	// 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+2, tmp, index,
	tmp.length - index);
	// set the listener array to the new array or null
	listenerList = (tmp.length == 0) ? NULL_ARRAY : tmp;
	}
	}

	/**
	* Return a string representation of the {@code AccessibilityListenerList}.
	*
	* @return a string representation of the {@code AccessibilityListenerList}.
	*/
	public String toString() {
	Object[] lList = listenerList;
	String s = "EventListenerList: ";
	s += lList.length/2 + " listeners: ";
	for (int i = 0 ; i <= lList.length-2 ; i+=2) {
	s += " type " + ((Class)lList[i]).getName();
	s += " listener " + lList[i+1];
	}
	return s;
	}
	}

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