Java Reference
In-Depth Information
(where possible). With GridBagLayout , elements can have different sizes and can occupy
multiple rows or columns.
There is only the no-argument constructor for GridBagLayout :
public GridBagLayout()
The position and behavior of each element is specified by an instance of the
GridBagConstraints class. By properly constraining the elements, you can specify the number
of rows and columns a component occupies, which component grows when additional screen
real estate is available, and various other restrictions. The actual grid size is based on the
number of components within the GridBagLayout and the GridBagConstraints of those objects.
For example, Figure 10-5 shows a GridBagLayout with seven components, arranged in a 3×3 grid.
Figure 10-5. GridBagLayout with seven components in a 3×3 grid
Note The maximum capacity of a screen using GridBagLayout is 512 rows by 512 columns. This is
specified by the protected MAXGRIDSIZE constant of the layout manager.
The code used to create Figure 10-5 is shown in Listing 10-1.
Listing 10-1. Seven-Button GridBagLayout
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.*;
public class GridBagButtons {
private static final Insets insets = new Insets(0,0,0,0);
public static void main(final String args[]) {
Runnable runner = new Runnable() {
public void run() {
final JFrame frame = new JFrame("GridBagLayout");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridBagLayout());
JButton button;
 
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