Java Reference
In-Depth Information
24
25
// Create a panel to group two labels
26 JPanel p2 =
new
JPanel(
new
GridLayout(
1
,
2
,
5
,
5
));
27 JLabel jlblRed =
new
JLabel(
"Red"
);
28 JLabel jlblOrange =
new
JLabel(
"Orange"
);
29 jlblRed.setForeground(Color.RED);
30
31
32 jlblOrange.setFont(largeFont);
33
34 jlblOrange.setBorder(lineBorder);
35 p2.add(jlblRed);
36 p2.add(jlblOrange);
37
38
39
// Add two panels to the frame
40 setLayout(
new
GridLayout(
2
,
1
,
5
,
5
));
41 add(p1);
42 add(p2);
43 }
44
45
public static void
main(String[] args) {
46
// Create a frame and set its properties
47 JFrame frame =
new
TestSwingCommonFeatures();
48 frame.setTitle(
"TestSwingCommonFeatures"
);
49 frame.setSize(
300
,
150
);
50 frame.setLocationRelativeTo(
null
);
// Center the frame
51 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
52 frame.setVisible(
true
);
53 }
54 }
set foreground
jlblOrange.setForeground(Color.ORANGE);
jlblRed.setFont(largeFont);
set font
jlblRed.setBorder(lineBorder);
set line border
p2.setBorder(
new
TitledBorder(
"Two Labels"
));
set titled border
Note
The same property may have different default values in different components. For example,
the
visible
property in
JFrame
is
false
by default, but it is
true
in every instance of
JComponent
(e.g.,
JButton
and
JLabel
) by default. To display a
JFrame
, you have
to invoke
setVisible(true)
to set the
visible
property
true
, but you don't have
to set this property for a
JButton
or a
JLabel
, because it is already
true
. To make a
JButton
or a
JLabel
invisible, you can invoke
setVisible(false)
. Please run the
program and see the effect after inserting the following two statements in line 38:
property default values
jbtLeft.setVisible(
false
);
jlblRed.setVisible(
false
);
12.21
How do you set background color, foreground color, font, and tool tip text on a Swing
GUI component?
12.22
Why is the tool tip text not displayed in the following code?
✓
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Check
Point
1
import
javax.swing.*;
2
3
public class
Test
extends
JFrame {
4
private
JButton jbtOK =
new
JButton(
"OK"
);
5
6
public static void
main(String[] args) {
7
// Create a frame and set its properties
8 JFrame frame =
new
Test();
9 frame.setTitle(
"Logic Error"
);
10 frame.setSize(
200
,
100
);
11 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);