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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.
*
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* 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.
*
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package com.sun.java.accessibility.util;
import java.util.*;
import java.beans.*;
import java.awt.*;
import java.awt.event.*;
import javax.accessibility.*;
The AccessibilityListenerList is a copy of the Swing EventListerList class.
/**
* <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
/**
* 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.
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.
Returns: an array of listener type, listener pairs.
/**
* 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.
Returns: the total number of listeners for this listener list.
/**
* 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.
Params: - t – the type of the listener to be counted
Returns: the number of listeners found
/**
* 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.
Params: - t – the type of the listener to be added
- l – the listener to be added
/**
* 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.
Params: - t – the type of the listener to be removed
- l – the listener to be removed
/**
* 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 AccessibilityListenerList. Returns: a string representation of the AccessibilityListenerList.
/**
* 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;
}
}