Select record from combo box & display in text field

ComboBox_Demo.java

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

class ComboBox_Demo extends JFrame
{
     JFrame frame = new JFrame(" ");
     JComboBox cb1, cb2;
     JTextField txtsub;
     Container cc;
     JLabel lblsub, sub;

     public ComboBox_Demo()
     {
          super(" COMBO LIST");
          txtsub = new JTextField(20);
          cb1 = new JComboBox();
          lblsub = new JLabel(" SELECT SUBJECT:");
          sub= new JLabel(" SUBJECT NAME:");
          cc = getContentPane();
          cc.setLayout(null);
          cc.add(lblsub);
          cc.add(cb1);
          cc.add(txtsub);
          cc.add(sub);

          setSize(500,300);
          setLocation(0,0);
          setResizable(false);
          setLayout(null);
          cc.setBackground(Color.pink);   
          setVisible(true);
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          lblsub.setBounds(50,50,250,40);
          cb1.setBounds(170,50,250,35);
          sub.setBounds(50,150,250,40);
          txtsub.setBounds(170,150,250,35);

          cb1.addItem("DATA STRUCTURE IN C");
          cb1.addItem("OBJECT ORIENTED IN C++");
          cb1.addItem("CORE JAVA");
          cb1.addItem("ADVANCE JAVA");
          cb1.addItem("DATABASE MANAGEMENT SYSTEM");
          cb1.addItem("ADVANCE DATABASE MANAGEMENT SYSTEM");
          cb1.addItem("OPERATING SYSTEM");
          cb1.addItem("NETWORKING");
          cb1.addItem("VISUAL BASIC");

          cb1.addItemListener(new ItemListener()
          {
               public void itemStateChanged(ItemEvent event)
               {
                    if (event.getStateChange() == ItemEvent.SELECTED)
                    {
                         try
                         {
                              String no=cb1.getSelectedItem().toString();
                              txtsub.setText(no);
                         }
                         catch (Exception ex)
                         {
                              ex.printStackTrace();
                         }
                    }
               }
          });
     }
     public static void main(String[] args)
     {
          new ComboBox_Demo();
     }
}