GridBagLayout 2 JPanels - One less width than other

Question

I would like to find out how exactly would I go about to having two JPanels on one JPanel, all using GridBagLayout.

Basically you have your Top Most JPanel and then with 2 JPanels on their as below requirement:

--------------------------------------
|                          |         |
|                          |         |
|                          |         |
|     JPanel 1             | JPanel  |
|                          |    2    |
|                          |         |
|                          |         |
--------------------------------------

Basically I would need JPanel 1 to be bigger than JPanel 2. But also JPanel 2 must NOT resize, JPanel 1 should only resize if the main panel gets resized.

Any idea's?

Answer 1

Have a look at this code example and see if this is what you wanted :

import java.awt.*;
import java.awt.event.*;
import java.util.Random;
import javax.swing.*;

public class GridBagExample {
    private JPanel leftPanel;
    private JPanel rightPanel;

    private GridBagConstraints gbc;
    private Random random;

    public GridBagExample() {
        gbc = new GridBagConstraints();
        gbc.anchor = GridBagConstraints.FIRST_LINE_START;
        gbc.insets = new Insets(5, 5, 5, 5);

        random = new Random();
    }

    private void displayGUI() {
        JFrame frame = new JFrame("Swing Worker Example");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        JPanel contentPane = getPanel();
        contentPane.setLayout(new GridBagLayout());
        leftPanel = getPanel();
        rightPanel = getPanel();

        addComp(contentPane, leftPanel, 0, 0, 1, 1,
                    GridBagConstraints.BOTH, 0.7, 1.0);
        addComp(contentPane, rightPanel, 1, 0, 1, 1,
                    GridBagConstraints.BOTH, 0.3, 1.0);

        frame.setContentPane(contentPane);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    private void addComp(JPanel panel, JComponent comp, int gridx,
                            int gridy, int gridwidth, int gridheight,
                                int fill, double weightx, double weighty) {
        gbc.gridx = gridx;
        gbc.gridy = gridy;
        gbc.gridwidth = gridwidth;
        gbc.gridheight = gridheight;
        gbc.fill = fill;
        gbc.weightx = weightx;
        gbc.weighty = weighty;

        panel.add(comp, gbc);
    }

    private JPanel getPanel() {
        JPanel panel = new JPanel();
        panel.setOpaque(true);
        panel.setBackground(new Color(random.nextInt(256),
                            random.nextInt(256), random.nextInt(256)));

        return panel;
    }

    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                new GridBagExample().displayGUI();
            }
        };
        EventQueue.invokeLater(runnable);
    }
}

Though if you want your right JPanel not to change size, you can pass GridBagConstraints.NONE to the function instead of GridBagConstraints.BOTH as done by me. Since without the actual contents known for this JPanel which will become its part, its hard to present its true size.

OUTPUT :

EDIT :

Updating my code, to better explain, as to what I am saying, though I used user2699405's (OP) ideas too from the comments.

import java.awt.*;
import java.awt.event.*;
import java.util.Random;
import javax.swing.*;

public class GridBagExample {
    private JPanel leftPanel;
    private JPanel rightPanel;

    private GridBagConstraints gbc;
    private Random random;

    public GridBagExample() {
        gbc = new GridBagConstraints();
        gbc.anchor = GridBagConstraints.FIRST_LINE_START;
        gbc.insets = new Insets(5, 5, 5, 5);

        random = new Random();
    }

    private void displayGUI() {
        JFrame frame = new JFrame("Swing Worker Example");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        JPanel contentPane = getPanel();
        contentPane.setLayout(new GridBagLayout());
        leftPanel = getPanel();
        rightPanel = new JPanel() {
            @Override
            public Dimension getPreferredSize() {
                return (new Dimension(100, 100));
            }
        };

        addComp(contentPane, leftPanel, 0, 0, 1, 1,
                    GridBagConstraints.BOTH, 1.0, 1.0);
        addComp(contentPane, rightPanel, 1, 0, 1, 1,
                    GridBagConstraints.NONE, 0.0, 1.0);

        frame.setContentPane(contentPane);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    private void addComp(JPanel panel, JComponent comp, int gridx,
                            int gridy, int gridwidth, int gridheight,
                                int fill, double weightx, double weighty) {
        gbc.gridx = gridx;
        gbc.gridy = gridy;
        gbc.gridwidth = gridwidth;
        gbc.gridheight = gridheight;
        gbc.fill = fill;
        gbc.weightx = weightx;
        gbc.weighty = weighty;

        panel.add(comp, gbc);
    }

    private JPanel getPanel() {
        JPanel panel = new JPanel();
        panel.setOpaque(true);
        panel.setBackground(new Color(random.nextInt(256),
                            random.nextInt(256), random.nextInt(256)));

        return panel;
    }

    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                new GridBagExample().displayGUI();
            }
        };
        EventQueue.invokeLater(runnable);
    }
}