Java Reference
In-Depth Information
The
GridLayout
layout manager divides the container into a
grid
so that components can
be placed in
rows
and
columns
. Class
GridLayout
inherits directly from class
Object
and
implements interface
LayoutManager
. Every
Component
in a
GridLayout
has the
same
width and height. Components are added to a
GridLayout
starting at the top-left cell of
the grid and proceeding left to right until the row is full. Then the process continues left
to right on the next row of the grid, and so on. The application of Figs. 12.43-12.44 dem-
onstrates the
GridLayout
layout manager by using six
JButton
s.
1
// Fig. 12.43: GridLayoutFrame.java
2
// GridLayout containing six buttons.
3
import
java.awt.GridLayout;
4
import
java.awt.Container;
5
import
java.awt.event.ActionListener;
6
import
java.awt.event.ActionEvent;
7
import
javax.swing.JFrame;
8
import
javax.swing.JButton;
9
10
public
class
GridLayoutFrame
extends
JFrame
implements
ActionListener
11
{
12
private final
JButton[] buttons;
// array of buttons
13
private
static final
String[] names =
14
{
"one"
,
"two"
,
"three"
,
"four"
,
"five"
,
"six"
};
15
private
boolean
toggle =
true
;
// toggle between two layouts
16
private final
Container container;
// frame container
17
private final
GridLayout gridLayout1;
// first gridlayout
private final
GridLayout gridLayout2;
// second gridlayout
18
19
20
// no-argument constructor
21
public
GridLayoutFrame()
22
{
23
super
(
"GridLayout Demo"
);
24
gridLayout1 =
new
GridLayout(
2
,
3
,
5
,
5
);
// 2 by 3; gaps of 5
gridLayout2 =
new
GridLayout(
3
,
2
);
// 3 by 2; no gaps
25
26
container = getContentPane();
27
setLayout(gridLayout1);
28
buttons =
new
JButton[names.length];
29
30
for
(
int
count =
0
; count < names.length; count++)
31
{
32
buttons[count] =
new
JButton(names[count]);
33
buttons[count].addActionListener(
this
);
// register listener
34
add(buttons[count]);
// add button to JFrame
35
}
36
}
37
38
// handle button events by toggling between layouts
39
@Override
40
public
void
actionPerformed(ActionEvent event)
41
{
Fig. 12.43
|
GridLayout
containing six buttons. (Part 1 of 2.)
