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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
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<HTML>
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<HEAD>
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<!--
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Copyright 1998-2006 Sun Microsystems, Inc. All Rights Reserved.
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DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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This code is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License version 2 only, as
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published by the Free Software Foundation. Sun designates this
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particular file as subject to the "Classpath" exception as provided
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by Sun in the LICENSE file that accompanied this code.
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This code is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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version 2 for more details (a copy is included in the LICENSE file that
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accompanied this code).
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You should have received a copy of the GNU General Public License version
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2 along with this work; if not, write to the Free Software Foundation,
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Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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CA 95054 USA or visit www.sun.com if you need additional information or
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have any questions.
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-->
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<META NAME="Author" Content="Eric Armstrong">
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<META HTTP-EQUIV="Content-Type" CONTENT="text/html;CHARSET=iso-8859-1">
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<TITLE>swing package</TITLE>
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</HEAD>
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<BODY bgcolor="white">
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<P>Provides a set of "lightweight"
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(all-Java language) components that,
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to the maximum degree possible, work the same on all platforms.
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For a programmer's guide to using these components, see
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<a href="http://java.sun.com/docs/books/tutorial/uiswing/index.html"
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target="_top">Creating
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a GUI with JFC/Swing</a>, a trail in <em>The Java Tutorial</em>.
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For other resources, see
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<a href="#related">Related Documentation</a>.
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<H2><a name="threading">Swing's Threading Policy</a></h2>
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In general Swing is not thread safe. All Swing components and related
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classes, unless otherwise documented, must be accessed on the event
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dispatching thread.
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<p>
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Typical Swing applications do processing in response to an event
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generated from a user gesture. For example, clicking on a {@code
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JButton} notifies all {@code ActionListeners} added to the {@code
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JButton}. As all events generated from a user gesture are
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dispatched on the event dispatching thread, most developers are not
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impacted by the restriction.
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<p>
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Where the impact lies, however, is in constructing and showing a
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Swing application. Calls to an application's {@code main} method,
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or methods in {@code Applet}, are not invoked on the event
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dispatching thread. As such, care must be taken to transfer control
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to the event dispatching thread when constructing and showing an
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application or applet. The preferred way to transfer control and begin
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working with Swing is to use {@code invokeLater}. The {@code
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invokeLater} method schedules a {@code Runnable} to be processed on
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the event dispatching thread. The following two examples work equally
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well for transferring control and starting up a Swing application:
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<pre>
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public class MyApp implements Runnable {
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public void run() {
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// Invoked on the event dispatching thread.
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// Construct and show GUI.
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}
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public static void main(String[] args) {
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SwingUtilities.invokeLater(new MyApp(args));
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}
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}
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</pre>
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Or:
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<pre>
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public class MyApp {
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MyApp(String[] args) {
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// Invoked on the event dispatching thread. Do any initialization
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// here.
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}
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public void show() {
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// Show the UI.
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}
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public static void main(final String[] args) {
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// Schedule a job for the event-dispatching thread:
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// creating and showing this application's GUI.
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SwingUtilities.invokeLater(new Runnable() {
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public void run() {
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new MyApp(args).show();
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}
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});
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}
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}
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</pre>
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This restriction also applies to models attached to Swing components.
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For example, if a {@code TableModel} is attached to a {@code
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JTable}, the {@code TableModel} should only be modified on the
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event dispatching thread. If you modify the model on a separate
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thread you run the risk of exceptions and possible display
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corruption.
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<p>
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As all events are delivered on the event dispatching thread, care must
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be taken in event processing. In particular, a long running task, such
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as network io or computational intensive processing, executed on the
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event dispatching thread blocks the event dispatching thread from
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dispatching any other events. While the event dispatching thread is
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blocked the application is completely unresponsive to user
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input. Refer to {@link javax.swing.SwingWorker} for the preferred way to do such
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processing when working with Swing.
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<p>
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More information on this topic can be found in the
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<a href="http://java.sun.com/docs/books/tutorial/uiswing/">Swing tutorial</a>,
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in particular the section on
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<a href="http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html">How to Use Threads</a>.
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<H2>
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<a name="related">Related Documentation</a>
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</H2>
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<P>For overviews, tutorials, examples, guides, and other documentation, please see:
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<UL>
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<LI><A HREF="http://java.sun.com/products/jfc/tsc/"
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target="_top">The Swing Connection</A>
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<LI><A HREF="http://java.sun.com/docs/books/tutorial/"
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target="_top">The Java Tutorial</A>
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<LI><A HREF="http://developer.java.sun.com/developer/onlineTraining/"
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target="_top">Online Training</A> at the Java Developer Connection<font size=-2><sup>SM</sup></font>
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<LI><A HREF="http://java.sun.com/products/jfc/"
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target="_top">Java Foundation Classes (JFC)</A> home page
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</UL>
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@serial exclude
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</BODY>
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</HTML>
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