Java Reference
In-Depth Information
10
gridBagFrame.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE
);
11
gridBagFrame.setSize(
300
,
150
);
12
gridBagFrame.setVisible(
true
);
13
}
14
}
// end class GridBagDemo
Fig. 22.22
|
Test class for
GridBagFrame
. (Part 2 of 2.)
GUI Overview
The GUI contains three
JButton
s, two
JTextArea
s, a
JComboBox
and a
JTextField
. The
layout manager is
GridBagLayout
. Lines 21-22 create the
GridBagLayout
object and set
the layout manager for the
JFrame
to
layout
. Line 23 creates the
GridBagConstraints
object used to determine the location and size of each component in the grid. Lines 26-
35 create each GUI component that will be added to the content pane.
JTextArea
textArea1
Lines 39-40 configure
JTextArea
textArea1
and add it to the content pane. The values
for
weightx
and
weighty
values are not specified in
constraints
, so each has the value
zero by default. Thus, the
JTextArea
will not resize itself even if space is available. How-
ever, it spans multiple rows, so the vertical size is subject to the
weighty
values of
JButton
s
button2
and
button3
. When either button is resized vertically based on its
weighty
value,
the
JTextArea
is also resized.
Line 39 sets variable
fill
in
constraints
to
GridBagConstraints.BOTH
, causing the
JTextArea
to always fill its entire allocated area in the grid. An
anchor
value is not speci-
fied in
constraints
, so the default
CENTER
is used. We do not use variable
anchor
in this
