Java Reference
In-Depth Information
The
setVisible
Method
Many classes of Swing objects have a
setVisible
method. The
setVisible
method takes
one argument of type
boolean
. If
w
is an object, such as a
JFrame
window, that can be dis-
played on the screen, then the call
w.setVisible(
true
);
will make
w
visible. The call
w.setVisible(
false
);
will hide
w
.
SYNTAX
Object_For_Screen
.setVisible(
Boolean_Expression
);
EXAMPLE (FROM DISPLAY 17.2)
public static void
main(String[] args)
{
JFrame firstWindow =
new
JFrame();
.
.
.
firstWindow.setVisible(
true
);
}
PITFALL: Forgetting to Program the Close-Window Button
The following lines from Display 17.2 ensure that when the user clicks the close-
window button, nothing happens:
firstWindow.setDefaultCloseOperation(
JFrame.DO_NOTHING_ON_CLOSE);
If you forget to program the close-window button, then the default action is as if you
had set it the following way:
firstWindow.setDefaultCloseOperation(
JFrame.HIDE_ON_CLOSE);
