By default, Swing uses a cross-platform look and feel called Metal. In most cases, it is more desirable to use a look and feel that is closer to the platform on which the application is being run. This example demonstrates how to retrieve and install the look and feel that most closely resembles the current platform. 
    // Get the native look and feel class name
    String nativeLF = UIManager.getSystemLookAndFeelClassName();
    
    // Install the look and feel
    try {
        UIManager.setLookAndFeel(nativeLF);
    } catch (InstantiationException e) {
    } catch (ClassNotFoundException e) {
    } catch (UnsupportedLookAndFeelException e) {
    } catch (IllegalAccessException e) {
    }

It is also possible to retrieve the cross-platform look and feel: 
    String javaLF = UIManager.getCrossPlatformLookAndFeelClassName();