Java Reference
In-Depth Information
■
Note
If you use the static creation methods of
JOptionPane
, the
JDialog
windows it creates automat-
ically have the Escape key registered to close the dialog.
Extending JDialog
If you need to extend
JDialog
, the class has two
protected
methods of importance:
protected void dialogInit()
protected JRootPane createRootPane()
The latter method is demonstrated in the previous example in Listing 8-4.
JApplet Class
The
JApplet
class is an extension to the AWT
Applet
class. For event handling to work properly
within applets that use Swing components, your applets must subclass
JApplet
instead of
Applet
.
The
JApplet
works the same as the other high-level containers by implementing the
RootPaneContainer
interface. One important difference between
JApplet
and
Applet
is the default
layout manager. Because you add components to the content pane of a
JApplet
, its default
layout manager is
BorderLayout
. This is unlike the default layout manager of
Applet
, which is
FlowLayout
. In addition, Swing applets can also have a menu bar, or more specifically a
JMenuBar
,
which is just another attribute of the
JRootPane
of the applet.
If you plan to deploy an applet that uses the Swing components, it is best to use the Java
Plug-in from Sun Microsystems, because that will install the Swing libraries with the runtime.
Tip
To make sure you are running the Java Plug-in under Internet Explorer, select Internet Options from
the Tools menu, and then choose the Advanced tab. Scroll down to the Java section immediately above
Microsoft VM and make sure Use JRE [VERSION] for <applet> (requires restart) is selected. If [VERSION] isn't
recent enough, you'll need to get a newer version from Sun at
http://www.java.com
.
■
If you need to extend the
JApplet
class, it has only one
protected
method of importance:
protected JRootPane createRootPane()
Working with a Desktop
Swing provides for the management of a set of frames within a common window or desktop. As
discussed in Chapter 1, this management is commonly called MDI. The frames can be layered
on top of one another or dragged around, and their appearance is specific to the current
look and feel. The frames are instances of the
JInternalFrame
class, whereas the desktop is a
specialized
JLayeredPane
called
JDesktopPane
. The management of the frames within a desktop
is the responsibility of a
DesktopManager
, in which the default implementation that's provided
is
DefaultDesktopManager
. The iconified form of a
JInternalFrame
on the desktop is represented
