/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* $Header:$
*/
package org.apache.beehive.controls.runtime.bean;
import java.util.TooManyListenersException;
/**
* The UnicastEventNotifier class provides basic callback listener management and event delivery
* services for unicast EventSets on ControlBean instances.
*/
public class UnicastEventNotifier implements java.io.Serializable
{
/**
* Adds a new callback event listener for this EventNotifier. This method will also
* perform a check to see if there is already a register listener, and throw a
* <code>java.util.TooManyListenersException</code> if there is already a registered
* listener.
*/
synchronized public void addListener(Object listener) throws TooManyListenersException
{
if (_listener != null)
throw new TooManyListenersException("Callback listener is already registered");
_listener = listener;
}
/**
* Remove an existing callback event listener for this EventNotifier
*/
synchronized public void removeListener(Object listener)
{
if (_listener != listener)
{
throw new IllegalStateException("Invalid listener, not currently registered");
}
_listener = null;
}
/**
* Returns the listener associated with this EventNotifier
*/
public Object getListener()
{
return _listener;
}
/**
* Returns the number of registered listeners
*/
public int getListenerCount()
{
return (_listener != null) ? 1 : 0;
}
/**
* Returns the listener list in array form
*/
public void getListeners(Object [] listeners)
{
if (_listener != null)
listeners[0] = _listener;
}
private Object _listener;
}