1 /*
2 * Copyright 1995-2007 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25 package java.awt;
26
27 import javax.accessibility;
28
29 /**
30 * <code>Panel</code> is the simplest container class. A panel
31 * provides space in which an application can attach any other
32 * component, including other panels.
33 * <p>
34 * The default layout manager for a panel is the
35 * <code>FlowLayout</code> layout manager.
36 *
37 * @author Sami Shaio
38 * @see java.awt.FlowLayout
39 * @since JDK1.0
40 */
41 public class Panel extends Container implements Accessible {
42 private static final String base = "panel";
43 private static int nameCounter = 0;
44
45 /*
46 * JDK 1.1 serialVersionUID
47 */
48 private static final long serialVersionUID = -2728009084054400034L;
49
50 /**
51 * Creates a new panel using the default layout manager.
52 * The default layout manager for all panels is the
53 * <code>FlowLayout</code> class.
54 */
55 public Panel() {
56 this(new FlowLayout());
57 }
58
59 /**
60 * Creates a new panel with the specified layout manager.
61 * @param layout the layout manager for this panel.
62 * @since JDK1.1
63 */
64 public Panel(LayoutManager layout) {
65 setLayout(layout);
66 }
67
68 /**
69 * Construct a name for this component. Called by getName() when the
70 * name is null.
71 */
72 String constructComponentName() {
73 synchronized (Panel.class) {
74 return base + nameCounter++;
75 }
76 }
77
78 /**
79 * Creates the Panel's peer. The peer allows you to modify the
80 * appearance of the panel without changing its functionality.
81 */
82
83 public void addNotify() {
84 synchronized (getTreeLock()) {
85 if (peer == null)
86 peer = getToolkit().createPanel(this);
87 super.addNotify();
88 }
89 }
90
91 /////////////////
92 // Accessibility support
93 ////////////////
94
95 /**
96 * Gets the AccessibleContext associated with this Panel.
97 * For panels, the AccessibleContext takes the form of an
98 * AccessibleAWTPanel.
99 * A new AccessibleAWTPanel instance is created if necessary.
100 *
101 * @return an AccessibleAWTPanel that serves as the
102 * AccessibleContext of this Panel
103 * @since 1.3
104 */
105 public AccessibleContext getAccessibleContext() {
106 if (accessibleContext == null) {
107 accessibleContext = new AccessibleAWTPanel();
108 }
109 return accessibleContext;
110 }
111
112 /**
113 * This class implements accessibility support for the
114 * <code>Panel</code> class. It provides an implementation of the
115 * Java Accessibility API appropriate to panel user-interface elements.
116 * @since 1.3
117 */
118 protected class AccessibleAWTPanel extends AccessibleAWTContainer {
119
120 private static final long serialVersionUID = -6409552226660031050L;
121
122 /**
123 * Get the role of this object.
124 *
125 * @return an instance of AccessibleRole describing the role of the
126 * object
127 */
128 public AccessibleRole getAccessibleRole() {
129 return AccessibleRole.PANEL;
130 }
131 }
132
133 }
Save This Page