import javax.swing.UIManager;import java.awt.*;public class RFrame {  boolean packFrame = false;  //Construct the application  public RFrame() {    MainFrame frame = new MainFrame();  }  //Main method  public static void main(String[] args) {    try {      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());    }    catch(Exception e) {      e.printStackTrace();    }    new RFrame();  }}