GridBagLayout why is the third column bigger?

Question

I'm trying to make the buttons equaly wide and together they should be as wide as the JTextField above them. code:

window.setLayout(new GridBagLayout());
GridBagConstraints gb = new GridBagConstraints();

gb.gridx = 0;
gb.gridy = 0;
gb.gridwidth = 3;
gb.fill = GridBagConstraints.HORIZONTAL;
gb.gridwidth = GridBagConstraints.REMAINDER;
window.add(text,gb); //adds JTextField

gb.gridwidth = 1;
gb.gridy++;
window.add(one,gb); //adds JButton
gb.gridx++;
window.add(two,gb); //adds JButton
gb.gridx++;
window.add(three,gb); //adds JButton

When I use gb.gridwidth = GridBagConstriants.RELATIVE; this happens:

Thanks in advance.

Answer 1

You can achieved this by setting GridBagConstraints.weightx = 1.0 for buttons.

Another key thing to notice is that I have added text field and buttons to a JPanel and then added that JPanel to the content pane of JFrame. I have not added text field and buttons directly to the content pane.

import javax.swing.*;
import java.awt.*;

public class EqualWidthButtons
{
  public static void main(String[] args)
  {
    JPanel panel = new JPanel();
    panel.setLayout(new GridBagLayout());

    GridBagConstraints gb = new GridBagConstraints();
    gb.gridx = 0;
    gb.gridy = 0;
    gb.gridwidth = 3;
    gb.fill = GridBagConstraints.HORIZONTAL;
    panel.add(new JTextField(20), gb);

    gb.gridwidth = 1;
    gb.gridy++;
    gb.weightx = 1.0; // This is the important line
    panel.add(new JButton("1"), gb);

    gb.gridx++;
    panel.add(new JButton("2"), gb);

    gb.gridx++;
    panel.add(new JButton("3"), gb);

    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().setLayout(new GridBagLayout());
    frame.getContentPane().add(panel, new GridBagConstraints());
    frame.setBounds(300, 200, 400, 300);
    frame.setVisible(true);
  }
}

Output: