/
AccessibilityListenerList.java
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/
AccessibilityListenerList.java
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/*
* Copyright (c) 2005, 2020, 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.
*
*/
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;
/**
* Constructs an {@code AccessibilityListenerList}.
*/
public AccessibilityListenerList() {}
/**
* 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<? extends EventListener> 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<? extends EventListener> 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<? extends EventListener> 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;
}
}