// look and feel that mimics the native OS UI
UIManager.setLookAndFeel( UIManager.getSystemLookAndFeelClassName() );

// cross platform Look and Feel (metal)
UIManager.setLookAndFeel( UIManager.getCrossPlatformLookAndFeelClassName() );

// windows look and feel
UIManager.setLookAndFeel( new com.sun.java.swing.plaf.windows.WindowsLookAndFeel() );

// windows classic look and feel
UIManager.setLookAndFeel( new com.sun.java.swing.plaf.windows.WindowsClassicLookAndFeel() );

// motif look and feel
UIManager.setLookAndFeel( new com.sun.java.swing.plaf.motif.MotifLookAndFeel() );

// metal look and feel
UIManager.setLookAndFeel( new javax.swing.plaf.metal.MetalLookAndFeel() );

// MacIntosh Look and feel
UIManager.setLookAndFeel( new it.unitn.ing.swing.plaf.macos.MacOSLookAndFeel() );

// Nimbus Look and Feel in JDK 1.6.0_10+
UIManager.setLookAndFeel( new com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel() );

// Linux GTK Look and feel
UIManager.setLookAndFeel( new com.sun.java.swing.plaf.gtk.GTKLooktAndFeel() );

// Alloy look and feel, you must buy from http://www.incors.com/lookandfeel/
com.incors.plaf.alloy.AlloyLookAndFeel.setProperty( "alloy.licenseCode", "xxxxxxx");
UIManager.setLookAndFeel( new com.incors.plaf.alloy.AlloyLookAndFeel(); )