Java - Peleando con GridBagLayout

public class GridBag extends JFrame{

	public GridBag() {

		setLayout(new GridBagLayout());

		GridBagConstraints restricciones = new GridBagConstraints();

		restricciones.gridx = 0;

		restricciones.gridy = 0;

		add(new JButton("Botón 1"), restricciones);

		restricciones.gridx = 3;

		restricciones.gridy = 0;

		add(new JButton("Botón 2"), restricciones);

		restricciones.gridx = 1;

		restricciones.gridy = 1;

		restricciones.gridheight = 2; //Dimensiones para Botón 3

		restricciones.gridwidth = 2;

		restricciones.fill = GridBagConstraints.BOTH;

		add(new JButton("Botón 3"), restricciones);

		restricciones.gridx = 0;

		restricciones.gridy = 3;

		restricciones.gridheight = 1; //Para Botón 4 revertimos las dimensiones anteriores

		restricciones.gridwidth = 1;

		add(new JButton("Botón 4"), restricciones);

		restricciones.gridx = 1;

		restricciones.gridy = 3;

		add(new JButton("Botón 5"), restricciones);

		restricciones.gridx = 2;

		restricciones.gridy = 3;

		restricciones.gridwidth = 2; //Botón 6 solo modificamos el ancho

		restricciones.fill = GridBagConstraints.HORIZONTAL;

		add(new JButton("Botón 6"), restricciones);

		setTitle("Ejemplo GridBagLayout");

		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

		pack();

		setResizable(false);

		setLocationRelativeTo(null);

		setVisible(true);

	}

	public static void main(String[] args) {

		SwingUtilities.invokeLater(new Runnable() {

			@Override

			public void run() {

				new GridBag();

			}

		});

	}

}

TestGrid() {

    setLayout(new GridBagLayout());

    GridBagConstraints ct = new GridBagConstraints();

    ct.gridx = 0;

    ct.gridy = 0;

    ct.fill = GridBagConstraints.BOTH;

    add(new JButton("Button 1"), ct);

    ct.gridx = 3;

    ct.gridy = 0;

    add(new JButton("Button 2"), ct);

    ct.gridx = 1;

    ct.gridy = 1;

    ct.gridwidth = 2;

    ct.gridheight = 2;

    add(new JButton("Button 3"), ct);

    ct.gridx = 0;

    ct.gridy = 3;

    ct.gridwidth = 1;

    ct.gridheight = 1;

    add(new JButton("Button 4"), ct);

    ct.gridx = 1;

    ct.gridy = 3;

    add(new JButton("Button 5"), ct);

    ct.gridx = 2;

    ct.gridy = 3;

    ct.gridwidth = 2;

    add(new JButton("Button 6"), ct);

    ct.gridx = 2;

    ct.gridy = 0;

    ct.gridwidth = 1;

    add(new JButton("Filler"), ct);

    ct.gridx = 0;

    ct.gridy = 2;

    add(new JButton("Filler"), ct);

    ct.gridx = 3;

    ct.gridy = 1;

    add(new JButton("Filler"), ct);

    pack();

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}