Row+colum

Question

How would go about accessing and changing these fields of the GridBagLayout class?
How come this is not working...
import java.awt.*;
public class GBag extends Panel {
public GBag() {
GridBagConstraints c = new GridBagConstraints();
Font f = new Font("Serif", 0, 52);
setFont(f);
GridBagLayout gbl = new GridBagLayout();
setLayout(gbl);
c.gridx = 0;
c.gridy = 0;
add(new Button("TL"), c);
c.gridx = 1;
add(new Button("Top Middle"), c);
c.gridx = 2;
add(new Button("TR"), c);
// weights
gbl.rowWeights[0] = 1; // NULL POINTER EXCEPTION!!
gbl.columnWeights[0] = 1;
public static void main(String args[]) {
Frame f = new Frame("GridBag Example");
f.add(new GBag(), BorderLayout.CENTER);
f.pack();
f.setVisible(true);

Answer 1

Hi 7tr7tr,
What I understood from your code is you are using single array. Please use double array.so double array is null by default.
Change your code:
1) gbl.rowWeights = new double[] {1.0};
2) gbl.columnWeights = new double[] {1.0};
And also your using GridBagConstraints weightX and weightY.
Here I modified your code.
mport java.awt.*;
public class GBag extends Panel {
public GBag() {
GridBagConstraints c = new GridBagConstraints();
Font f = new Font("Serif", 0, 52);
setFont(f);
GridBagLayout gbl = new GridBagLayout();
setLayout(gbl);
c.gridx = 0;
c.gridy = 0;
add(new Button("TL"), c);
c.gridx = 1;
add(new Button("Top Middle"), c);
c.gridx = 2;
add(new Button("TR"), c);
// weights
gbl.rowWeights = new double[] {1.0};
gbl.columnWeights = new double[] {1.0};
public static void main(String args[]) {
Frame f = new Frame("GridBag Example");
f.add(new GBag(), BorderLayout.CENTER);
f.pack();
f.setVisible(true);
I hope this will help you out.
Regards,
Tirumalarao
Developer Technical Support,
Sun Microsystems,
http://www.sun.com/developers/support.