Java订票系统

package flight.assist;   
   
import flight.manage.*;   
import flight.assist.*;   
import flight.query.*;   
   
import java.util.*;   
import java.sql.*;    
   
public class UpdateComboBox extends Thread   
{   
    private SqlBean sqlBean = new SqlBean();   
    private HashSet flight = new HashSet();   
    private HashSet airFirm = new HashSet();   
    private HashSet place = new HashSet();   
    public final static int INSERT_INFO = 1;   
    public final static int DELETE_INFO = 2;   
       
    public UpdateComboBox()   
    {   
          
           //Start the thread   
        this.start();   
    }   
       
    public void run()   
    {   
        try   
        {   

            while (true)   
            {   
                updateInsert();   
                updateDelete();   
                   
                   //Stop the thread every 2 seconds   
                this.sleep(2000);          
            }          
        }   
        catch(Exception e)   
        {   
            e.printStackTrace();   
        }      
    }      
       
    public void updateInsert()   
    {   
        String sqlString = "select flight,airfirm,start from flight";   
        String newFlightNum = "";   
        String newAirFirm = "";   
        String newPlace = "";          
       
        try   
        {   
            ResultSet rs = sqlBean.executeQuery(sqlString);   
               
            while (rs.next())   
            {   
                newFlightNum = rs.getString("flight");   
                newAirFirm = rs.getString("airfirm");