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Java > Open Source Codes > nextapp > echo2 > app > Composite


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;
31
32 /**
33  * Generic composite component base class.
34  * This class is intended to be used as base class for composite components.
35  * This component will simply display its content without any modification to
36  * its appearance or behavior. This component may have at most one child
37  * component.
38  * <p>
39  * See the <code>Panel</code> component for a default implementation of a
40  * single-child container component.
41  * <p>
42  * This class provides no benefit if you are providing a custom client/server
43  * synchronization peer. If you wish to create a component with a custom
44  * client/server synchronization peer, <code>Component</code> itself should be
45  * derived instead of this class.
46  */
47 public abstract class Composite extends Component {
48
49     public Composite() {
50         super();
51     }
52     
53     /**
54      * Allow at most one child component.
55      *
56      * @see nextapp.echo2.app.Component#isValidChild(nextapp.echo2.app.Component)
57      */
58     public boolean isValidChild(Component child) {
59         return getComponentCount() == 0 || indexOf(child) != -1;
60     }
61 }
62
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