JMenuBar Java Swing

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;


class MenuExample {
    JFrame frame;


    MenuExample(){
        frame = new JFrame();
        JMenuBar menuBar = new JMenuBar();
        JMenu file = new JMenu("file");
        JMenu export = new JMenu("Export");

        JMenuItem createFile = new JMenuItem("create");
        JMenuItem png = new JMenuItem("as png");
        JMenuItem jpg = new JMenuItem("as jpg");
        export.add(png);
        export.add(jpg);
        menuBar.add(file);
        file.add(createFile);
        file.add(export);
        frame.setJMenuBar(menuBar);
        frame.setSize(400,400);
        frame.setVisible(true);
    }
}

public class GUI{

    public static void main(String[] args){

        new MenuExample();

    }


}