1 /*
2 * Copyright (c) 1998, 2017, Oracle and/or its affiliates. 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 /**
27 * Provides a set of "lightweight" (all-Java language) components
28 * that, to the maximum degree possible, work the same on all platforms. For a
29 * programmer's guide to using these components, see
30 * <a href="http://docs.oracle.com/javase/tutorial/uiswing/index.html"
31 * target="_top">Creating a GUI with JFC/Swing</a>, a trail in
32 * <em>The Java Tutorial</em>. For other resources, see
33 * <a href="#related">Related Documentation</a>.
34 *
35 * <h2><a id="threading">Swing's Threading Policy</a></h2>
36 * In general Swing is not thread safe. All Swing components and related
37 * classes, unless otherwise documented, must be accessed on the event
38 * dispatching thread.
39 * <p>
40 * Typical Swing applications do processing in response to an event generated
41 * from a user gesture. For example, clicking on a {@code JButton} notifies all
42 * {@code ActionListeners} added to the {@code JButton}. As all events generated
43 * from a user gesture are dispatched on the event dispatching thread, most
44 * developers are not impacted by the restriction.
45 * <p>
46 * Where the impact lies, however, is in constructing and showing a Swing
47 * application. Calls to an application's {@code main} method, or methods in
48 * {@code Applet}, are not invoked on the event dispatching thread. As such,
49 * care must be taken to transfer control to the event dispatching thread when
50 * constructing and showing an application or applet. The preferred way to
51 * transfer control and begin working with Swing is to use {@code invokeLater}.
52 * The {@code invokeLater} method schedules a {@code Runnable} to be processed
53 * on the event dispatching thread. The following two examples work equally well
54 * for transferring control and starting up a Swing application:
55 * <pre>
56 * import javax.swing.SwingUtilities;
57 *
58 * public class MyApp implements Runnable {
59 * public void run() {
60 * // Invoked on the event dispatching thread.
61 * // Construct and show GUI.
62 * }
63 *
64 * public static void main(String[] args) {
65 * SwingUtilities.invokeLater(new MyApp());
66 * }
67 * }</pre>
68 * Or:<pre>
69 * import javax.swing.SwingUtilities;
70 *
71 * public class MyApp {
72 * MyApp(String[] args) {
73 * // Invoked on the event dispatching thread.
74 * // Do any initialization here.
75 * }
76 *
77 * public void show() {
78 * // Show the UI.
79 * }
80 *
81 * public static void main(final String[] args) {
82 * // Schedule a job for the event-dispatching thread:
83 * // creating and showing this application's GUI.
84 * SwingUtilities.invokeLater(new Runnable() {
85 * public void run() {
86 * new MyApp(args).show();
87 * }
88 * });
89 * }
90 * }</pre>
91 * This restriction also applies to models attached to Swing components. For
92 * example, if a {@code TableModel} is attached to a {@code JTable}, the
93 * {@code TableModel} should only be modified on the event dispatching thread.
94 * If you modify the model on a separate thread you run the risk of exceptions
95 * and possible display corruption.
96 * <p>
97 * As all events are delivered on the event dispatching thread, care must be
98 * taken in event processing. In particular, a long running task, such as
99 * network io or computational intensive processing, executed on the event
100 * dispatching thread blocks the event dispatching thread from dispatching any
101 * other events. While the event dispatching thread is blocked the application
102 * is completely unresponsive to user input. Refer to
103 * {@link javax.swing.SwingWorker} for the preferred way to do such processing
104 * when working with Swing.
105 * <p>
106 * More information on this topic can be found in the
107 * <a href="http://docs.oracle.com/javase/tutorial/uiswing/">Swing tutorial</a>,
108 * in particular the section on
109 * <a
110 * href="http://docs.oracle.com/javase/tutorial/uiswing/concurrency/index.html">
111 * Concurrency in Swing</a>.
112 *
113 * <h2><a id="related">Related Documentation</a></h2>
114 * For overviews, tutorials, examples, guides, and other documentation,
115 * please see:
116 * <ul>
117 * <li><a href="http://www.oracle.com/technetwork/java/javase/tech/articles-jsp-139072.html"
118 * target="_top">The Swing Connection</a></li>
119 * <li><a href="http://docs.oracle.com/javase/tutorial/"
120 * target="_top">The Java Tutorial</a></li>
121 * <li><a href="http://www.oracle.com/technetwork/java/javase/training/index.html"
122 * target="_top">Online Training</a>
123 * at the Java Developer Connection <sup>SM</sup></li>
124 * <li><a href="http://www.oracle.com/technetwork/java/javase/tech/index-jsp-142216.html"
125 * target="_top">Java Foundation Classes (JFC)</a> home page</li>
126 * </ul>
127 *
128 * @serial exclude
129 */
130 package javax.swing;