when i am compiling the following servlet program it compiles the successfully.but when i try to run the program it gives the following error. Exception in thread "main" java.lang.NoSuchMethodError: main

Here is the my code:

import java.io.*;
import java.lang.*; 
import java.sql.*;
import javax.servlet.*; 
import javax.servlet.http.*;

public abstract class InsertServlet extends HttpServlet{
    public void doPost(HttpServletRequest req,HttpServletResponse res) throws ServletException,IOException {
        res.setContentType("text/html");
        int count=0; 
        PrintWriter out= res.getWriter(); 
        String FirstName=req.getParameter("FirstName");
        String LastName=req.getParameter("LastName");
        String Email=req.getParameter("Email");
        String Password=req.getParameter("Password"); 
        String ConformPassword=req.getParameter("ConformPassword");
        String Dateofbirth=req.getParameter("Dateofbirth"); 
        int Age=Integer.parseInt(req.getParameter("Age"));
        String Gender=req.getParameter("Gender");
        String Address=req.getParameter("Address"); 
        String Country=req.getParameter("Country");
        String State=req.getParameter("State"); 
        String City=req.getParameter("City"); 
        int Telephone=Integer.parseInt(req.getParameter("Telephone"));
        int Mobile=Integer.parseInt(req.getParameter("Mobile")); 
        String Howdidyouhear=req.getParameter("Howdidyouhear");
        PreparedStatement pstm=null; 

  try{
         Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver ");
         String ConnectionUrl = ("jdbc:sqlserver://localhost:1433;database=sree;integratedSecurity=true");
        Connection con= DriverManager.getConnection(ConnectionUrl, "PRATAP", " ");
                  pstm=con.prepareStatement("insert into stureg(?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)"); 
                  pstm.setString(1,FirstName);
                  pstm.setString(2,LastName);
                  pstm.setString(3,Email);
                  pstm.setString(4,Password);
                  pstm.setString(5,ConformPassword);
                  pstm.setString(6,Dateofbirth);
                  pstm.setInt(7,Age);
                  pstm.setString(8,Gender);
                  pstm.setString(9,Address);
                  pstm.setString(10,Country);
                  pstm.setString(11,State);
                  pstm.setString(12,City);
                  pstm.setInt(13,Telephone);
                  pstm.setInt(14,Mobile);
                  pstm.setString(15,Howdidyouhear);
                  int i = pstm.executeUpdate();
                  String sql = "select * from stureg";
                  PreparedStatement prest = con.prepareStatement(sql);
                  ResultSet rs = prest.executeQuery();
                  while(rs.next())
                 {
                      out.println(rs.getString(1) +"FirstName");
                      out.println(rs.getString(2) +"LastName");
                      out.println(rs.getString(3) +"Email");
                      out.println(rs.getString(4) +"Password");
                      out.println(rs.getString(5) +"ConformPassword");
                      out.println(rs.getString(6) +"Dateofbirth");
                      out.println(rs.getInt(7) +"Age");
                      out.println(rs.getString(8) +"Gender");
                      out.println(rs.getString(9) +"Address");
                      out.println(rs.getString(10) +"Country");
                      out.println(rs.getString(11) +"State");
                      out.println(rs.getString(12) +"City");
                      out.println(rs.getInt(13) +"Telephone");
                      out.println(rs.getInt(14) +"Mobile");
                      out.println(rs.getInt(15) +"Howdidyouhear");
                      if(i!=0)
                        {
                           System.out.print("<br>Record has been inserted");
                        }                      
                     else
                        {
                           System.out.print("failed to insert the data");
                        }

             }
}
                   catch(Exception e){
                   out.println(e);
                   }
                }
            }

tell me the solution for this problem.And how can we deploy the servlet in Tomcat