    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.net.util;
    019
    020import java.io.Serializable;
    021import java.util.EventListener;
    022import java.util.Iterator;
    023import java.util.concurrent.CopyOnWriteArrayList;
    024
    025/**
    026 */
    027
    028public class ListenerList implements Serializable, Iterable<EventListener>
    029{
    030    private static final long serialVersionUID = -1934227607974228213L;
    031
    032    private final CopyOnWriteArrayList<EventListener> listeners;
    033
    034    public ListenerList()
    035    {
    036        listeners = new CopyOnWriteArrayList<>();
    037    }
    038
    039    public void addListener(final EventListener listener)
    040    {
    041            listeners.add(listener);
    042    }
    043
    044    public  void removeListener(final EventListener listener)
    045    {
    046            listeners.remove(listener);
    047    }
    048
    049    public int getListenerCount()
    050    {
    051        return listeners.size();
    052    }
    053
    054    /**
    055     * Return an {@link Iterator} for the {@link EventListener} instances.
    056     *
    057     * @return an {@link Iterator} for the {@link EventListener} instances
    058     * @since 2.0
    059     * TODO Check that this is a good defensive strategy
    060     */
    061    @Override
    062    public Iterator<EventListener> iterator() {
    063            return listeners.iterator();
    064    }
    065
    066}