01: /*
02: * This file is part of the Echo Web Application Framework (hereinafter "Echo").
03: * Copyright (C) 2002-2005 NextApp, Inc.
04: *
05: * Version: MPL 1.1/GPL 2.0/LGPL 2.1
06: *
07: * The contents of this file are subject to the Mozilla Public License Version
08: * 1.1 (the "License"); you may not use this file except in compliance with
09: * 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: }
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