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Java > Open Source Codes > org > jboss > aspects > patterns > observable > SubjectImpl


1 /*
2   * JBoss, Home of Professional Open Source
3   * Copyright 2005, JBoss Inc., and individual contributors as indicated
4   * by the @authors tag. See the copyright.txt in the distribution for a
5   * full listing of individual contributors.
6   *
7   * This is free software; you can redistribute it and/or modify it
8   * under the terms of the GNU Lesser General Public License as
9   * published by the Free Software Foundation; either version 2.1 of
10   * the License, or (at your option) any later version.
11   *
12   * This software is distributed in the hope that it will be useful,
13   * but WITHOUT ANY WARRANTY; without even the implied warranty of
14   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15   * Lesser General Public License for more details.
16   *
17   * You should have received a copy of the GNU Lesser General Public
18   * License along with this software; if not, write to the Free
19   * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20   * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
21   */
22 package org.jboss.aspects.patterns.observable;
23
24 import java.util.Collections JavaDoc;
25 import java.util.HashSet JavaDoc;
26 import java.util.Iterator JavaDoc;
27 import java.util.Set JavaDoc;
28
29 /**
30  * The subject implementation.
31  *
32  * @author <a HREF="adrian@jboss.com">Adrian Brock</a>
33  * @version $Revision: 37406 $
34  */
35 public class SubjectImpl implements Subject
36 {
37    /** The observers */
38    private Set JavaDoc observers = Collections.synchronizedSet(new HashSet JavaDoc());
39    
40    /** The subject */
41    private Object JavaDoc subject;
42
43    public SubjectImpl(Object JavaDoc subject)
44    {
45       this.subject = subject;
46    }
47    
48    public void addObserver(Observer observer)
49    {
50       if(observers.contains(observer))
51          return; // return right away since we have that already.
52 observers.add(observer);
53    }
54    
55    public void removeObserver(Observer observer)
56    {
57       observers.remove(observer);
58    }
59    
60    public void notifyObservers()
61    {
62       Subject obj = (Subject) subject;
63       
64       synchronized (observers)
65       {
66          for (Iterator JavaDoc i = observers.iterator(); i.hasNext();)
67          {
68             Observer observer = (Observer) i.next();
69             observer.fireChange(obj);
70          }
71       }
72    }
73 }
74
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