GridbagConstraints going bad?

Question

I want 1 component to take 80% of the availible x-axis space and the other to take 20%. I do know how the theory works, but I don't know why the examples below won't work this way.
Well... everything there is to say is included in this small code snippet... should be runnable.
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestWeight extends JPanel {
    private static final long serialVersionUID = 1L;
    static JFrame frame;
    public TestWeight() {
        super(new BorderLayout());
        JPanel panel1 = new JPanel(new GridBagLayout());
        panel1.setBorder(BorderFactory.createTitledBorder("Misbehaviour on dimension-fixed width TextFields"));
        JTextField t1 = new JTextField();
        JTextField t2 = new JTextField();
        JTextField t3 = new JTextField();
        t1.setMinimumSize(new Dimension(600, t1.getPreferredSize().height));
        t2.setMinimumSize(new Dimension(600, t2.getPreferredSize().height));
        t3.setMinimumSize(new Dimension(600, t3.getPreferredSize().height));
        t1.setPreferredSize(new Dimension(600, t1.getPreferredSize().height));
        t2.setPreferredSize(new Dimension(600, t2.getPreferredSize().height));
        t3.setPreferredSize(new Dimension(600, t3.getPreferredSize().height));
        t1.setText("t1, c.weightx == 1.0, preferred size width == 600");
        t2.setText("t2, 0.8, 600");
        t3.setText("t3, 0.2, 600");
        GridBagConstraints c = new GridBagConstraints();
        c.anchor = GridBagConstraints.LINE_START;
        c.gridwidth = 2;
        c.weightx = 1.0;
        c.gridx = 0; c.gridy = 0; panel1.add(t1, c);
        c.gridwidth = 1;
        c.weightx = 0.8;
        c.gridx = 0; c.gridy = 1; panel1.add(t2, c);
        c.weightx = 0.2;
        c.gridx = 1; c.gridy = 1; panel1.add(t3, c);
        JPanel panel2 = new JPanel(new GridBagLayout());
        panel2.setBorder(BorderFactory.createTitledBorder("Right behaviour on shorter TextFields, but TextField size is wrong"));
        JTextField t4 = new JTextField();
        JTextField t5 = new JTextField(7);
        JTextField t6 = new JTextField(7);
        t4.setMinimumSize(new Dimension(4000, t4.getPreferredSize().height));
        t4.setPreferredSize(new Dimension(4000, t4.getPreferredSize().height));
        t4.setText("t4, c.weightx == 1.0, preferred size width == 4,000 (also same behaviour with anything > 600");
        t5.setText("t5, 0.8");
        t6.setText("t6, 0.2");
        c.gridwidth = 2;
        c.weightx = 1.0;
        c.gridx = 0; c.gridy = 0; panel2.add(t4, c);
        c.gridwidth = 1;
        c.weightx = 0.8;
        c.gridx = 0; c.gridy = 1; panel2.add(t5, c);
        c.weightx = 0.2;
        c.gridx = 1; c.gridy = 1; panel2.add(t6, c);
        add(panel1, BorderLayout.NORTH);
        add(panel2, BorderLayout.SOUTH);
    private static void createAndShowGUI() {
        frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JComponent newContentPane = new TestWeight();
        newContentPane.setOpaque(true);
        frame.setContentPane(newContentPane);
        frame.setSize(600, 180);
        frame.setTitle("Test");
        frame.setVisible(true);
    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, UnsupportedLookAndFeelException {
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
}Thanks for looking into it!

Answer 1

Try dragging the right side of the frame to the right to see what happens when
t3 can be displayed at its prefWidth.
The relative weight proportions aren't literal; you have to play with them.
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import java.awt.Insets;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
public class TestWeightRx extends JPanel {
    private static final long serialVersionUID = 1L;
    static JFrame frame;
    public TestWeightRx() {
        super(new BorderLayout());
        final JPanel panel1 = new JPanel(new GridBagLayout());
        panel1.setBorder(BorderFactory.createTitledBorder("Misbehaviour on " +
                "dimension-fixed width TextFields"));
        JTextField t1 = new JTextField();
        final JTextField t2 = new JTextField();
        final JTextField t3 = new JTextField();
        t1.setMinimumSize(new Dimension(600, t1.getPreferredSize().height));
        t2.setMinimumSize(new Dimension(600, t2.getPreferredSize().height));
        t3.setMinimumSize(new Dimension(600, t3.getPreferredSize().height));
        t1.setPreferredSize(new Dimension(600, t1.getPreferredSize().height));
        t2.setPreferredSize(new Dimension(600, t2.getPreferredSize().height));
        t3.setPreferredSize(new Dimension(600, t3.getPreferredSize().height));
        Dimension d = t1.getPreferredSize();
        d.width = 600;
        t1.setPreferredSize(d);
        t2.setPreferredSize(d);
        t3.setPreferredSize(d);
        t1.setText("t1, c.weightx == 1.0, preferred size width == 600");
        t2.setText("t2, 0.8, 600");
        t3.setText("t3, 0.2, 600");
        GridBagConstraints c = new GridBagConstraints();
        c.anchor = GridBagConstraints.LINE_START;
        c.fill = GridBagConstraints.HORIZONTAL;
        c.gridwidth = 2;
        c.weightx = 1.0;
        c.gridx = 0; c.gridy = 0; panel1.add(t1, c);
        c.gridwidth = 1;
        c.weightx = 0.46;
        c.gridx = 0; c.gridy = 1; panel1.add(t2, c);
        c.weightx = 0.1125;
        c.gridx = 1; c.gridy = 1; panel1.add(t3, c);
        JPanel panel2 = new JPanel(new GridBagLayout());
        panel2.setBorder(BorderFactory.createTitledBorder("Right behaviour " +
                "on shorter TextFields, but TextField size is wrong"));
        JTextField t4 = new JTextField();
        JTextField t5 = new JTextField(7);
        JTextField t6 = new JTextField(7);
        t4.setMinimumSize(new Dimension(4000, t4.getPreferredSize().height));
        t4.setPreferredSize(new Dimension(4000, t4.getPreferredSize().height));
        t4.setText("t4, c.weightx == 1.0, preferred size width == 4,000 " +
                "(also same behaviour with anything > 600");
        t5.setText("t5, 0.8");
        t6.setText("t6, 0.2");
        c.gridwidth = 2;
        c.weightx = 1.0;
        c.gridx = 0; c.gridy = 0; panel2.add(t4, c);
        c.gridwidth = 1;
        c.weightx = 0.8;
        c.gridx = 0; c.gridy = 1; panel2.add(t5, c);
        c.weightx = 0.2;
        c.gridx = 1; c.gridy = 1; panel2.add(t6, c);
        add(panel1, BorderLayout.NORTH);
        add(panel2, BorderLayout.SOUTH);
        addComponentListener(new ComponentAdapter() {
            public void componentResized(ComponentEvent e) {
                Insets insets = panel1.getInsets();
                int w = panel1.getWidth() - insets.left - insets.right;
                int t2w = t2.getWidth();
                int t3w = t3.getWidth();
                double pct2 = (double)t2w/w;
                double pct3 = (double)t3w/w;
                System.out.printf("width = %d  t2 width = %d/%.3f  " +
                                  "t3 width = %d/%.3f%n",
                                   w, t2w, pct2, t3w, pct3);
    public static void main(String[] args) {
        frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JComponent newContentPane = new TestWeightRx();
        newContentPane.setOpaque(true);
        frame.setContentPane(newContentPane);
        frame.setSize(600, 180);
        frame.setTitle("Test");
        frame.setVisible(true);
}