Java Reference
In-Depth Information
f.setResizable(false);
f.setVisible(true);
}
};
EventQueue.invokeLater(r);
}
}
Listing 7-6
presents a similar architecture to that shown in
Listing 7-2
.
However,
it also demonstrates various Swing features, including Swing components/containers,
ImageIcon
, tooltips, borders, and
setDefaultCloseOperation()
.
Because Swing component classes have similar APIs to their AWT counterparts,
you can often just prefix an AWT class name with
J
to refer to the equivalent Swing
class—don'tforgettochangetheimportstatement.Forexample,prefix
Label
with
J
to change from AWT's
Label
class to
javax.swing.JLabel
.
ImageIcon
is instantiated to load a thermometer icon image—behind the scenes
MediaTracker
isusedtoensurethattheimageiscompletelyloaded.The
ImageI-
con
instance is then passed to the constructor of each
JButton
instance so that the
button will display this icon along with its label.
Tooltips are handy for presenting small help messages that assist the user in in-
teracting with the GUI.
Listing 7-6
demonstrates this feature by invoking
setToolTipText()
on each of the
txtDegrees
and
txtResult
textfields.
Whentheusermovesthemouseoveratextfield,atooltipwillappeartorevealitshelp
message.
Listing7-6
attachesanetchedbordertothepanelsurroundingthepairofbuttons,to
setthemapartfromtheothercomponents.Becausethisborderbuttsupagainsttheframe
window,anemptyborderiscreatedandassignedtotheframe'srootpanetoleavesome
space around this window's edges.
The
setDefaultCloseOperation()
method and its
DISPOSE_ON_CLOSE
argument reduces verbosity by disposing of a window (in response to a user close re-
quest) without having to install a window listener.
You may have noticed that I've placed the
void fixGUI(Container c)
class method before the
pack()
method call, instead of placing it after
pack()
as I
pack()
because (in AWT) preferred sizes are not available until after the
pack()
methodcall,and
fixGUI()
needstoaccesspreferredsizes.InSwing,preferredsizes
