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Java > Open Source Codes > nextapp > echo2 > app > button > ButtonGroup


1 /*
2  * This file is part of the Echo Web Application Framework (hereinafter "Echo").
3  * Copyright (C) 2002-2005 NextApp, Inc.
4  *
5  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
6  *
7  * The contents of this file are subject to the Mozilla Public License Version
8  * 1.1 (the "License"); you may not use this file except in compliance with
9  * the License. You may obtain a copy of the License at
10  * http://www.mozilla.org/MPL/
11  *
12  * Software distributed under the License is distributed on an "AS IS" basis,
13  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
14  * for the specific language governing rights and limitations under the
15  * License.
16  *
17  * Alternatively, the contents of this file may be used under the terms of
18  * either the GNU General Public License Version 2 or later (the "GPL"), or
19  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
20  * in which case the provisions of the GPL or the LGPL are applicable instead
21  * of those above. If you wish to allow use of your version of this file only
22  * under the terms of either the GPL or the LGPL, and not to allow others to
23  * use your version of this file under the terms of the MPL, indicate your
24  * decision by deleting the provisions above and replace them with the notice
25  * and other provisions required by the GPL or the LGPL. If you do not delete
26  * the provisions above, a recipient may use your version of this file under
27  * the terms of any one of the MPL, the GPL or the LGPL.
28  */
29
30 package nextapp.echo2.app.button;
31
32 import java.io.Serializable JavaDoc;
33 import java.util.HashSet JavaDoc;
34 import java.util.Iterator JavaDoc;
35 import java.util.Set JavaDoc;
36
37 import nextapp.echo2.app.ApplicationInstance;
38 import nextapp.echo2.app.RenderIdSupport;
39 import nextapp.echo2.app.RadioButton;
40
41 /**
42  * A collection of radio buttons which allows the selection of only one
43  * radio button at a time.
44  */
45 public class ButtonGroup
46 implements RenderIdSupport, Serializable JavaDoc {
47     
48     private static final RadioButton[] EMPTY = new RadioButton[0];
49     
50     private String JavaDoc id = ApplicationInstance.generateSystemId();
51     private Set JavaDoc buttons;
52     
53     /**
54      * Adds a <code>RadioButton</code> to the group.
55      * Applications should use <code>RadioButton.setGroup()</code> to add
56      * buttons from a group rather than invoking this method.
57      *
58      * @param radioButton the <code>RadioButton</code> to add
59      * @see RadioButton#setGroup(ButtonGroup)
60      */
61     public void addButton(RadioButton radioButton) {
62         if (buttons == null) {
63             buttons = new HashSet JavaDoc();
64         }
65         buttons.add(radioButton);
66         updateSelection(radioButton);
67     }
68     
69     /**
70      * Returns all <code>RadioButton</code>s in the group.
71      *
72      * @return the <code>RadioButton</code>
73      */
74     public RadioButton[] getButtons() {
75         if (buttons == null) {
76             return EMPTY;
77         } else {
78             return (RadioButton[]) buttons.toArray(new RadioButton[buttons.size()]);
79         }
80     }
81     
82     /**
83      * @see nextapp.echo2.app.RenderIdSupport#getRenderId()
84      */
85     public String JavaDoc getRenderId() {
86         return id;
87     }
88     
89     /**
90      * Removes a <code>RadioButton</code> from the group.
91      * Applications should use <code>RadioButton.setGroup()</code> to remove
92      * buttons from a group rather than invoking this method.
93      *
94      * @param radioButton the <code>RadioButton</code> to remove
95      * @see RadioButton#setGroup(ButtonGroup)
96      */
97     public void removeButton(RadioButton radioButton) {
98         if (buttons != null) {
99             buttons.remove(radioButton);
100         }
101     }
102     
103     /**
104      * Notifies the <code>ButtonGroup</code> that a <code>RadioButton</code>
105      * within its domain may have changed state.
106      *
107      * @param changedButton the changed <code>RadioButton</code>
108      */
109     public void updateSelection(RadioButton changedButton) {
110         if (buttons == null || !changedButton.isSelected()) {
111             return;
112         }
113         Iterator JavaDoc buttonIt = buttons.iterator();
114         while (buttonIt.hasNext()) {
115             RadioButton button = (RadioButton) buttonIt.next();
116             if (!button.equals(changedButton)) {
117                 button.setSelected(false);
118             }
119         }
120     }
121 }
122
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