Java JComboBox add element

import java.awt.FlowLayout;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;

class Demo extends JPanel {
  public Demo() {
    JComboBox<String> jcb;
    String options[] = { "CSS", "HTML", "Java", "Javascript" };
    setLayout(new FlowLayout());
    jcb = new JComboBox<String>(options);
    //  w ww. ja v a 2  s  . c  o m
    jcb.addItem("A");
    jcb.addItem("B");
    jcb.addItem("C");
    
    
    add(jcb);

  }
}

public class Main {
  public static void main(String[] args) {
    Demo panel = new Demo();
    JFrame application = new JFrame();
    application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    application.add(panel);
    application.setSize(250, 250);
    application.setVisible(true);
  }
}