1 //----------------------------------------------------------------------
2 //
3 // PerfectJPattern: "Design patterns are good but components are better!"
4 // Subject.java Copyright (c) 2007 Giovanni Azua Garcia
5 // bravegag@hotmail.com
6 //
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License
9 // as published by the Free Software Foundation; either version 2
10 // of the License, or (at your option) any later version.
11 //
12 // This program 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
15 // GNU General Public License for more details.
16 //
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
20 // MA 02110-1301, USA.
21 //
22 //----------------------------------------------------------------------
23 package perfectjpattern.core.behavioral.observer;
24
25 import java.util.ArrayList;
26 import java.util.Arrays;
27 import java.util.Collection;
28
29 import org.apache.commons.lang.Validate;
30
31 import perfectjpattern.core.api.behavioral.observer.IObserver;
32 import perfectjpattern.core.api.behavioral.observer.ISubject;
33 import perfectjpattern.core.api.behavioral.observer.data.IEventData;
34
35 /***
36 * Base core implementation of <code>ISubject</code> interface.
37 * <br>
38 *
39 * @see ISubject
40 *
41 * @param <E> Type of event data this <code>ISubject</code>
42 * notifies with.
43 *
44 * @author <a href="mailto:bravegag@hotmail.com">Giovanni Azua</a>
45 * @version $Revision: 1.0 $ $Date: Jun 18, 2007 9:06:39 PM $
46 */
47 public
48 class Subject<E extends IEventData>
49 implements ISubject<E>
50 {
51 //------------------------------------------------------------------------
52 // public
53 //------------------------------------------------------------------------
54 /* (non-Javadoc)
55 * @see perfectjpattern.core.api.behavioral.observer.ISubject#
56 * attach(perfectjpattern.core.api.behavioral.observer.IObserver<E>[])
57 */
58 public void
59 attach(IObserver<E>... anObservers)
60 {
61 Validate.notNull(anObservers, "'anObservers' must not be null.");
62
63 theObservers.addAll(Arrays.asList(anObservers));
64 }
65
66 //------------------------------------------------------------------------
67 /* (non-Javadoc)
68 * @see perfectjpattern.core.api.behavioral.observer.
69 * ISubject#clear()
70 */
71 public void
72 clear()
73 {
74 theObservers.clear();
75 }
76
77 //------------------------------------------------------------------------
78 /* (non-Javadoc)
79 * @see perfectjpattern.core.api.behavioral.observer.ISubject#
80 * detach(perfectjpattern.core.api.behavioral.observer.IObserver<E>[])
81 */
82 public void
83 detach(IObserver<E>... anObservers)
84 {
85 Validate.notNull(anObservers, "'anObservers' must not be null.");
86
87 theObservers.removeAll(Arrays.asList(anObservers));
88 }
89
90 //------------------------------------------------------------------------
91 /* (non-Javadoc)
92 * @see perfectjpattern.core.api.behavioral.observer.ISubject#
93 * notifyObservers(perfectjpattern.core.api.behavioral.observer.data.
94 * IEventData)
95 */
96 public void
97 notifyObservers(E anEventData)
98 {
99 Validate.notNull(anEventData, "'anEventData' must not be null.");
100
101 for (IObserver<E> myObserver : theObservers)
102 {
103 myObserver.update(anEventData);
104 }
105 }
106
107 //------------------------------------------------------------------------
108 /* (non-Javadoc)
109 * @see perfectjpattern.core.api.behavioral.observer.ISubject#size()
110 */
111 public int
112 size()
113 {
114 return theObservers.size();
115 }
116
117 //------------------------------------------------------------------------
118 // members
119 //------------------------------------------------------------------------
120 /***
121 * Collection of <code>IObserver</code> instances.
122 */
123 private final Collection<IObserver<E>> theObservers =
124 new ArrayList<IObserver<E>>();
125 }