gridwidth
This constraint identifies the number of columns that the component spans,
and its default value is 1. For example, in the screenshot below, the
button in the third row spans both columns:
The code to create this display is as follows:
import java.awt.*;
import javax.swing.*;
public class ColumnSpan {
public static void main(String[] args) {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container pane = f.getContentPane();
pane.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 1;
gbc.gridy = GridBagConstraints.RELATIVE;
pane.add(new JButton("First row, first column"), gbc);
pane.add(new JButton("Second row"), gbc);
gbc.gridwidth = 2;
pane.add(new JButton("Third row, spans two columns"), gbc);
gbc.gridwidth = 1;
gbc.gridx = GridBagConstraints.RELATIVE;
pane.add(new JButton("First row, second column"), gbc);
f.setSize(400, 300);
f.setVisible(true);
}
}
In this case, the button's size is set to its preferred width, and the
button is centered horizontally within its display area. However, it can be
made to fill both columns by setting the fill value:
import java.awt.*;
import javax.swing.*;
public class ColumnSpan {
public static void main(String[] args) {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container pane = f.getContentPane();
pane.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 1;
gbc.gridy = GridBagConstraints.RELATIVE;
pane.add(new JButton("First row, first column"), gbc);
pane.add(new JButton("Second row"), gbc);
gbc.gridwidth = 2;
gbc.fill = GridBagConstraints.HORIZONTAL;
pane.add(new JButton("Third row, spans two columns"), gbc);
gbc.gridwidth = 1;
gbc.fill = GridBagConstraints.NONE;
gbc.gridx = GridBagConstraints.RELATIVE;
pane.add(new JButton("First row, second column"), gbc);
f.setSize(400, 300);
f.setVisible(true);
}
}
With these alterations, the second being to reset the fill
value, the display now becomes:
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