hi friend,

Try the following code may, this will be helpful for you.

package net.roseindia.swingExample;

import java.awt.event.*;
import java.sql.*;
import java.util.HashSet;
import java.util.Iterator;

import javax.swing.*;
public class EditableComboBox implements ActionListener{

    String[] petStrings = { "Bird", "Cat", "Dog", "Rabbit", "Pig" };
    String petName ="";
    JComboBox petList;
    JButton button;

private void createUI()
    {
        JFrame frame = new JFrame("Editable Combo Box");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);       
        frame.setLayout(null);      

        JLabel label = new JLabel("Select from list : ");
        button = new JButton("Insert");
        button.addActionListener(this);
        label.setBounds(10, 30, 100, 20);
        button.setBounds(275, 30, 100, 20);
        petList = new JComboBox(petStrings);

        petList.setBounds(110, 30, 150, 30);
        petList.setSelectedIndex(0);         

        frame.add(button);
        frame.add(label);
        frame.add(petList);

        frame.setVisible(true);
        frame.setSize(400, 300);        
    }

@Override
public void actionPerformed(ActionEvent e){

    HashSet set = new HashSet();
    if(e.getSource() == button)
    {
        String[] newList = new String[petStrings.length+1];
        petName = (String)petList.getSelectedItem();
        int i = 0;
        while(i < petStrings.length)
        {
            newList[i]= petStrings[i];
            set.add(newList[i]);            
            i++;
        }
        newList[i] = petName;
        set.add(newList[i]);        
        Iterator itr = set.iterator();
        while(itr.hasNext())
        {
            String s = (String) itr.next();         
            if(petName.equals(s))
            {
                addOperation();
            }
        }       
        petList.setEditable(true);
      }
}

 private void addOperation()
 {
    try
    {
        Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
        Connection con = DriverManager.getConnection("jdbc:odbc:swing");
        String sql = "INSERT INTO PetTable(petName) Values('"+petName+"')";
        Statement st = con.createStatement();
        st.execute(sql);
        JOptionPane.showMessageDialog(null, "Record Added Succesfully.","Record Added",
                JOptionPane.INFORMATION_MESSAGE);
    }
    catch(Exception e)
    {
        JOptionPane.showMessageDialog(null, e.getMessage(),"Error",
                JOptionPane.ERROR_MESSAGE);
    }
  }
 public static void main(String args[])
 {
     EditableComboBox gvb = new EditableComboBox();
     gvb.createUI();
 }
}// class closed

Thanks.