1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.net.util;
19
20 import java.io.ObjectInputStream;
21 import java.io.ObjectOutputStream;
22 import java.io.Serializable;
23 import java.util.EventListener;
24 import java.util.Iterator;
25 import java.util.concurrent.CopyOnWriteArrayList;
26
27 /**
28 */
29
30 public class ListenerList implements Serializable, Iterable<EventListener> {
31 private static final long serialVersionUID = -1934227607974228213L;
32
33 private final CopyOnWriteArrayList<EventListener> listeners;
34
35 public ListenerList() {
36 listeners = new CopyOnWriteArrayList<>();
37 }
38
39 public void addListener(final EventListener listener) {
40 listeners.add(listener);
41 }
42
43 public int getListenerCount() {
44 return listeners.size();
45 }
46
47 /**
48 * Return an {@link Iterator} for the {@link EventListener} instances.
49 *
50 * @return an {@link Iterator} for the {@link EventListener} instances
51 * @since 2.0 TODO Check that this is a good defensive strategy
52 */
53 @Override
54 public Iterator<EventListener> iterator() {
55 return listeners.iterator();
56 }
57
58 private void readObject(final ObjectInputStream in) {
59 throw new UnsupportedOperationException("Serialization is not supported");
60 }
61
62 /*
63 * Serialization is unnecessary for this class. Reject attempts to do so until such time as the Serializable attribute can be dropped.
64 */
65
66 public void removeListener(final EventListener listener) {
67 listeners.remove(listener);
68 }
69
70 private void writeObject(final ObjectOutputStream out) {
71 throw new UnsupportedOperationException("Serialization is not supported");
72 }
73
74 }