private void setLookAndFeel(int theme) {
        switch (theme) {
            case 0: 
                try {
                    UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
                }
                catch (Exception exc) {
                    System.err.println("ERROR - Themes: Metal (default) theme can't be set. " + exc.getMessage());
                }
                break;
            case 1: 
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                }
                catch (Exception exc) {
                    System.err.println("ERROR - Themes: Motif (system's look) theme can't be set. " + exc.getMessage());
                }
                break;
            case 2:
                try {
                    UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
                }
                catch (Exception exc) {
                    System.err.println("ERROR - Themes: Nimbus theme can't be set. " + exc.getMessage());
                }
                break;
        }
    }