EventNotifier


1   package org.apache.beehive.controls.runtime.bean;
2   /*
3    * Copyright 2004 The Apache Software Foundation.
4    *
5    * Licensed under the Apache License, Version 2.0 (the "License");
6    * you may not use this file except in compliance with the License.
7    * 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   * $Header:$
18   */
19  
20  import java.util.ArrayList  ;
21  import java.util.Iterator  ;
22  
23  /**
24   * The EventNotifier class provides basic callback listener management and event delivery
25   * services for ControlBean instances. 
26   */
27  public class EventNotifier implements java.io.Serializable  
28  {
29      /**
30       * Adds a new callback event listener for this EventNotifier
31       */
32      synchronized public void addListener(Object   listener)
33      {
34          _listeners.add(listener);
35      }
36  
37      /**
38       * Remove an existing callback event listener for this EventNotifier
39       */
40      synchronized public void removeListener(Object   listener)
41      {
42          if (!_listeners.contains(listener))
43              throw new IllegalStateException  ("Invalid listener, not currently registered");
44  
45          _listeners.remove(listener);
46      }
47  
48      /**
49       * Returns an iterator over the full set of listeners
50       */
51      public Iterator   listenerIterator()
52      {
53          return _listeners.iterator();
54      }
55  
56      /**
57       * Returns the number of registered listeners
58       */
59      public int getListenerCount()
60      {
61          return _listeners.size();
62      }
63  
64      /**
65       * Returns the listener list in array form
66       */
67      public void getListeners(Object   [] listeners)
68      {
69          _listeners.toArray(listeners);
70      }
71  
72      private ArrayList   _listeners = new ArrayList  ();
73  }
74
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