Java gridbaglayout adjusting

Question

This is an extension to this question: Java gridbaglayout problems. Panel1 is overlapping panel2 because of the panel1's width overflow. However, if i remove the gc.gridwidth = 2 it will align panel2 properly, but it will also move the combobox to the its original spot on the right side. I have been playing around with the different gridbaglayout properties but can't get it aligned like i want it to.

Heres my code:

public void createGUI()
{
   main_panel = new JPanel();
   main_panel.setLayout(new GridBagLayout());
   GridBagConstraints gc = new GridBagConstraints();

   gc.fill = GridBagConstraints.HORIZONTAL;
   gc.gridx = 0;
   gc.gridy = 0;
   gc.insets = new Insets(5, 0, 10, 0);
   main_panel.add(label, gc);

   gc.fill = GridBagConstraints.HORIZONTAL;
   gc.gridx = 1;
   gc.gridy = 0;
   gc.insets = new Insets(5, 0, 10, 0);
   main_panel.add(band_combobox, gc);

   gc.fill = GridBagConstraints.HORIZONTAL;
   gc.gridx = 0;
   gc.gridy = 1;
   gc.gridwidth = 2;
   gc.insets = new Insets(0, 0, 10, 0);
   main_panel.add(panel1, gc);

   gc.fill = GridBagConstraints.HORIZONTAL;
   gc.gridx = 1;
   gc.gridy = 1;
   gc.gridwidth = 2;
   gc.insets = new Insets(0, 0, 10, 0);
   main_panel.add(panel2, gc);

   gc.fill = GridBagConstraints.HORIZONTAL;
   gc.gridx = 0;
   gc.gridy = 2;
   gc.gridwidth = 2;
   gc.insets = new Insets(0, 0, 10, 0);
   main_panel.add(panel3, gc);
}

I am trying to do something like this:

Answer 1

Don't be afraid to use compound layouts to achieve your needs. Your label and combo box want to "float" on the top row. This would be a difficult thing to achieve with a GridBagLayout on it's own, but by adding them to another container, with a different layout manager, it's achievable...

When you change a components gridWidth or gridHeight it will allow them to "flow" over into other columns and rows, meaning that they may sit above or below components that occupy that space, depending on when they are added...

Also, check out the weight properties.

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.TitledBorder;

public class TestPane {
    private JPanel main_panel;

    public static void main(String[] args) {
        new TestPane();
    }

    public TestPane() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                createGUI();;

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(main_panel);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public void createGUI() {

        main_panel = new JPanel();
        main_panel.setLayout(new GridBagLayout());
        GridBagConstraints gc = new GridBagConstraints();

        JLabel label = new JLabel("Band Directory");
        JComboBox band_combobox = new JComboBox();

        JPanel panel1 = new JPanel();
        panel1.add(new JLabel("1"));
        panel1.setBorder(new TitledBorder("Panel1"));
        JPanel panel2 = new JPanel();
        panel2.setBorder(new TitledBorder("Panel2"));
        panel2.add(new JLabel("2"));
        JPanel panel3 = new JPanel();
        panel3.setBorder(new TitledBorder("Panel3"));
        panel3.add(new JLabel("3"));

        JPanel top = new JPanel();
        top.add(label);
        top.add(band_combobox);

        gc.fill = GridBagConstraints.HORIZONTAL;
        gc.weightx = 1;
        gc.gridx = 0;
        gc.gridy = 0;
        gc.gridwidth = GridBagConstraints.REMAINDER;
        gc.insets = new Insets(5, 0, 10, 0);
        main_panel.add(top, gc);

        gc.gridwidth = 1;
        gc.weightx = 0.5;
        gc.gridx = 0;
        gc.gridy = 1;
        gc.insets = new Insets(0, 0, 10, 0);
        main_panel.add(panel1, gc);

        gc.gridx = 1;
        gc.gridy = 1;
        gc.insets = new Insets(0, 0, 10, 0);
        main_panel.add(panel2, gc);

        gc.fill = GridBagConstraints.HORIZONTAL;
        gc.weightx = 1;
        gc.gridx = 0;
        gc.gridy = 2;
        gc.gridwidth = GridBagConstraints.REMAINDER;
        gc.insets = new Insets(0, 0, 10, 0);
        main_panel.add(panel3, gc);
    }
}

You might find it useful to have a read through How to use GridBagLayout