LookAndFeels de Java

import java.awt.*; import javax.swing.*; public class Program extends JFrame implements ActionListener
{
   private JButton metalButton = new JButton("Metal");
   private JButton motifButton = new JButton("Motif");
   private JButton windowsButton = new JButton("Windows");

   public Program()
   {
      super("LookAndFeels");
      Container container = this.getContentPane();

      container.add(metalButton);
      container.add(motifButton);
      container.add(windowsButton);

      metalButton.addActionListener(this);
      motifButton.addActionListener(this);
      windowsButton.addActionListener(this);

      this.setSize(300, 200);
      this.setVisible(true);
   }

   public void actionPerformed(ActionEvent evt)
   {
       Object source = evt.getSource();
       String theme = "";
       if (source == metalButton)
       theme = "javax.swing.plaf.metal.MetalLookAndFeel";
       else if (source == motifButton)
       theme = "com.sun.java.swing.plaf.motif.MotifLookAndFeel";
       else if (source == windowsButton)
       theme = "com.sun.java.swing.plaf.windows.WindowsLookAndFeel";
       try
      {
         UIManager.setLookAndFeel(theme);
         SwingUtilities.updateComponentTreeUI(this);
      }
      catch (Exception e)
      {
         System.exit(0);
      }
   }

   public static void main(String[] args)
   {
        Program program = new Program();
   }
}