Cambio de apariencia

muestra la applet con la apariencia Metal, Motify  y la de Windows. Cambiar entre estas apariencias es tan
fácil como hacer clic sobre un botón de opción.

package masterdavidjavabasico;

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


/*
<APPLET
    CODE=plaf.class
    WIDTH=210
    HEIGHT=200 >
</APPLET>
*/

public class plaf extends JApplet
{

    JRadioButton b1 = new JRadioButton("Metal"),
    b2 = new JRadioButton("Motif"),
    b3 = new JRadioButton("Windows");

    public void init()
    {
        Container contentPane = getContentPane();
        contentPane.add(new jpanel(), BorderLayout.CENTER);
    }

    class jpanel extends JPanel implements ActionListener
    {
        public jpanel()
        {
            add(new JButton("JBoton"));
            add(new JTextField("JCuadro_de_texto"));
            add(new JCheckBox("JCasilla_de_activacion"));
            add(new JRadioButton("JBoton_de_opcion"));
            add(new JLabel("JEtiqueta"));
            add(new JList(new String[] {
                "JLista Elemento 1", "JLista Elemento 2","JLista Elemento 3"}));
            add(new JScrollBar(SwingConstants.HORIZONTAL));

            ButtonGroup group = new ButtonGroup();
            group.add(b1);
            group.add(b2);
            group.add(b3);

            b1.addActionListener(this);
            b2.addActionListener(this);
            b3.addActionListener(this);

            add(b1);
            add(b2);
            add(b3);
        }

        public void actionPerformed(ActionEvent e)
        {
            JRadioButton src = (JRadioButton)e.getSource();

            try {
                if((JRadioButton)e.getSource() == b1)
                    UIManager.setLookAndFeel(
                      "javax.swing.plaf.metal.MetalLookAndFeel");
                else if((JRadioButton)e.getSource() == b2)
                    UIManager.setLookAndFeel(
                        "com.sun.java.swing.plaf.motif.MotifLookAndFeel");
                else if((JRadioButton)e.getSource() == b3)
                    UIManager.setLookAndFeel(
                        "com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
            }
            catch(Exception ex) {}

            SwingUtilities.updateComponentTreeUI(getContentPane());
        }
    }
}