Java Glossary : Swing

Java definitions: 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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Sun's set of lightweight GUI components that give much fancier screen displays than the raw AWT. Since they are written in pure Java, they run the same on all platforms, unlike the AWT. They are part of the JFC. They support pluggable look and feel -- not by using the native platform's facilities but by roughly emulating them. This means you can get any supported look and feel on any platform. The disadvantage of lightweight components is slower execution. The advantage is uniform behaviour on all platforms.

The biggest gotcha is that you no longer add directly to your Swing containers. Any content inside a JFrame should be placed inside its contentPane. You must do a:

Container pane = swingContainer.getContentPane();

and add to it. Unfortunately the add method is still defined for the Swing Containers to entrap the unwary.

pane

In Swing, override JComponent.paintComponent instead of paint.

Swing's JComboBox is misnamed. It does not let you select a combination of choices. It is a combination Choice and write-in TextField allowing the user to add new possible choices on the fly. Swing classes live in package javax.swing.* . They used to live in com.sun.java.swing.*.

FormattedTextField does not verify input the way you might expect. To learn how to do that you need to read up on custom Documents and InputVerifier.

Swing Threads

Unlike the AWT, Swing is not threadsafe. You can't directly meddle with Swing components, or their backing data models from a second thread. The contract is, if you want to do anything to a Swing component that could have any effect on it's display from an application thread (not the EventDispatchThread itself), you should add it to the event dispatch thread's queue via SwingUtilities.invokeLater( Runnable ) or SwingUtilities.invokeAndWait( Runnable ) so that it will be done on the same thread that Swing itself uses. The good news is, even though you are using Runnable, you don't have the overhead of actually creating a new Thread since you are just calling the run method on the already existing Swing thread.

There are a few exceptions to this general rule, most notably it is safe to call repaint and revalidate, JTextComponent.setText and JTextArea.append from any thread.

AWT vs Swing

Which should you use, AWT or Swing?

The advantage of Swing is it gives you finer control over the look and feel of your components. You can create a prettier app. They look the same on all platforms. AWT apps tend to look amateurish and Spartan.
AWT supports Ctrl-C Ctrl-V copy/paste without any coding. In Swing, it requires page and pages of bubblegum. Further you can't do it at all in unsigned Swing JApplets.
Swing is bigger and more complicated, and is not supported by earlier JVMs.
With Swing you must deal with the infuriatingly pointless complexity of ContentPanes.
AWT uses native GUI components where Swing draws everything itself with lightweight components using high level code. AWT thus tends to be faster.
Swing has JSpinner, JSLider and JColorChooser. There are no equivalents in Swing.

Equivalent Components in AWT and Swing
Applet	JApplet
Button	JButton
Canvas	JPanel
Checkbox	JCheckBox or JRadioButton
Choice	JComboBox
Color	Color
none	JColorChooser
Component	JComponent
Container	Container
Dialog	JDialog or JOptionPane
FileDialog	JFileChooser
none	JFormattedTextField
Frame	JFrame
Label	JLabel
List	JList + JScrollPane
LayoutManager	LayoutManager
Menu	JMenu
Panel	JPanel
ScrollPane	JScrollPane
none	JSlider
none	JSpinner
TextArea	JTextArea
TextField	JTextField
Window	JWindow

Difference Between Window Types

What are the differences between a Applet, Canvas, Component, Container, Dialog, Frame, JApplet, JComponent, JContainer, JDialog, JInternalFrame, JPanel, JFrame, JWindow, Panel and Window?

When the following table suggests a Component is for AWT but not Swing, it means there is an improved Swing component. In theory you could use the old AWT component, but normally you would not want to.

When it asks if Components are visible, it means, are the visible by default when first created. Obviously you set do a setVisible( true ) later. The rule of thumb is, freestanding windows start out invisible and everything else starts out visible. Another way of looking at it is, everything derived from Window starts out invisible.

The paned refers to whether you use getContentPane.setLayout or simply setLayout.

Differences Between Various Types of Windows
class	What Is It	AWT	Swing	Visible	Paned	Derived From	Default Layout
Applet	represents the featureless Window provided by the browser for an Applet to run in.	Y	N	true	N	Panel	FlowLayout
Button	Not a window. It is here is an example of a Component.	Y	N	true	N	Component	n/a
Canvas	an area you can use the low level drawing tools on, rather than dropping in components placed with a LayoutManager. Raw material for creating your own components. Just a place you can draw. It cannot contain Components. For Swing, use a JPanel instead.	Y	N	true	N	Component	n/a
Component	Not a window. It is an abstract class underlying Buttons etc.	Y	N	true	N	Object	n/a
Container	These are the basis on which all the other windows are built. They manage the child Components and LayoutManager. They are missing an addNotify method to create the peer object, so can't appear on screen. You don't normally instantiate Containers directly, but some subclass of them.	Y	Y	true	N	Component	null
Dialog	A pop-up box to deliver an error message or alert. Temporary Window for displaying information or requesting keystrokes. It requires a parent Frame, thus in cannot be used inside an Applet which has no Frame. It can be modal, which means it blocks input to all other Windows until it is dismissed. It must have a Frame mentioned in the constructor.	Y	N	false	N	Window	BorderLayout
Frame	A resizable, movable window with title bar and close button. Usually it contains Panels.	Y	N	false	N	Window	BorderLayout
JApplet	represents the featureless Window provided by the browser for an Applet to run in.	N	Y	true	Y	Applet	FlowLayout
JButton	Not a window. It is here is an example of a JComponent.	N	Y	true	N	AbstractButton, JComponent	n/a
JComponent	Not a window. It is an abstract class underlying JButtons etc.	N	Y	true	N	Container, not Component, Container!	n/a
JContainer	There is no such beast! Since Containers have no on screen aspect, the ordinary AWT Container suffices.	n/a	n/a	n/a	n/a	n/a	n/a
JDialog	A pop-up box to deliver an error message or alert. Usually created with JOptionPane methods. Temporary Window for displaying information or requesting keystrokes. It requires a parent JFrame, thus in cannot be used inside an JApplet which has no JFrame. It can be modal, which means it blocks input to all other JWindows until it is dismissed. You can place complex arrays of Components on JDialogs, not just simple error messages.	N	Y	false	Y	Dialog	BorderLayout
JFrame	A resizable, movable window with title bar and close button. Usually it contains JPanels. The entire application is usually a JFrame.	N	Y	false	Y	Frame	BorderLayout
JInternalFrame	Independent windows that the user can resized and move, but only within an enclosing JFrame.	N	Y	false	Y	JComponent	BorderLayout
JOptionPane	A modal pop-up box to deliver an error message or alert. Temporary Window for displaying information or requesting keystrokes. It requires a parent JFrame, thus in cannot be used inside an JApplet which has no JFrame. Unlike a JDialog, JOptionPanes are always modal, which means they block input to all other JWindows until they are dismissed.	N	Y	false	Y	JDialog	BorderLayout
JPanel	A region internal to a JFrame or another JPanel. Used for grouping components together. Optionally bounded by a visible border. Lives inside some enclosing Container.	N	Y	true	N	JComponent	FlowLayout
JWindow	A window without a title bar or move controls. The program can move and resize it, but the user cannot. It has no border at all.	N	Y	false	Y	Window	BorderLayout
Panel	A region internal to a Frame or another Panel. Used for grouping components together. Not bounded by a visible border. You can change background colour of a panel to delimit it though. Lives inside some enclosing Container.	Y	N	true	N	Container	FlowLayout
Window	A window without a title bar or move controls. The program can move and resize it, but the user cannot. Free standing Window, not inside any other Window. It must have Frame mentioned in the constructor.	Y	N	false	N	Container	BorderLayout

Applet ¤ Canvas ¤ Container ¤ decorated ¤ Dialog ¤ Frame ¤ JApplet ¤ JDialog ¤ JFrame ¤ JInternalFrame ¤ JPanel ¤ JWindow ¤ pane ¤ Panel ¤ Window

AWT component Summary : available:

on the web at java.Sun.com
on J: in the JDK 1.4.2_04: J:\j2sdk1.4.2_04\docs\api\java\awt\package-summary.html
on J: in the JDK 1.5 beta: J:\Program Files\Java\j2sdk1.5.0\docs\api\java\awt\package-summary.html

Swing component summary : available:

on the web at java.Sun.com
on J: in the JDK 1.4.2_04: J:\j2sdk1.4.2_04\docs\api\javax\swing\package-summary.html
on J: in the JDK 1.5 beta: J:\Program Files\Java\j2sdk1.5.0\docs\api\javax\swing\package-summary.html

Books

Java Swing

1-56592-455-X

Robert Eckstein, Marc Loy and Dave Wood

John Zukowski's Definitive Guide to Swing for Java 2 with CD-ROM

1-893115-02-X

John Zukowski

very clear writer

Core Swing Advanced Programming

0-13-083292-8

Kim Topley

On reading the Amazon reviews, this book looks best for HTML rendering.

Swing, Second Edition

1-930110-88-X

Matthew Robinson, Pavel Vorobiev, David Anderson

A relatively deep book. Also covers printing.

For a great overview what is possible with Swing, see the SwingSet2 demo that comes part of the JDK download. Run it with this command:

cd J:\j2sdk1.4.2_04\demo\jfc\swingset2]
java -jar Swingset2.jar

AFC ¤ Applet ¤ AWT ¤ Canvas ¤ Christian Kaufhold's Java and Swing Know-How ¤ Container ¤ decorated ¤ Dialog ¤ Exceptions to the single-thread rule ¤ Frame ¤ IFC ¤ JApplet ¤ JButton ¤ JCheckbox ¤ JComboBox ¤ JDialog ¤ JEditorPane ¤ JFC ¤ JFrame ¤ JInternalFrame ¤ JList ¤ JPanel ¤ JRadioButton ¤ JSlider ¤ JSpinner ¤ JWindow ¤ Karsten Lentsch's Pages on Swing design ¤ LAF ¤ Metal L & F icons ¤ pane ¤ Panel ¤ sightings ¤ Swing Examples ¤ Swing tutorial ¤ Swing article index ¤ The Swing Connection (TSC) ¤ Threads And Swing ¤ Using a Swing Worker Thread ¤ Window ¤ Working with Asynchronous Models

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