Error showing when connecting to MySQL using servlet

Question

This is my Program. (MySQL.java)
package coreservlets;
import java.sql.*;
public class MySQL {
     public static void main (String[] args) {
     String driver = "com.mysql.jdbc.Driver";
     String url = "jdbc:mysql://localhost/leave_app";
     String username = "";
     String password = "";
     showEmployeeTable(driver, url, username, password);
public static void showEmployeeTable(String driver,
String url,
String username,
String password)
try{
               Class.forName(driver);
Connection connection = DriverManager.getConnection(url, username, password);
               Statement statement = connection.createStatement();
               String query = "Select userid from userlogin";
               ResultSet resultSet = statement.executeQuery(query);
               while(resultSet.next()){
                    System.out.print(resultSet.getString("userid"));
               connection.close();
               } catch(ClassNotFoundException cnfe) {
                    System.err.println("Error loading driver: " + cnfe);
               } catch(SQLException sqle) {
                         System.err.println("Error with connection: " + sqle);
Error showing
java.lang.ClassCastException: coreservlets.MySQL cannot be cast to javax.servlet.Servlet
     org.apache.catalina.servlets.InvokerServlet.serveRequest(InvokerServlet.java:370)
     org.apache.catalina.servlets.InvokerServlet.doGet(InvokerServlet.java:134)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
Could someone help me to resolve this bug?

Answer 1

Hi,
I think you have misunderstood me. What I'm trying to say is that your MySQL.java doesn't seems to be the root cause of the problem.
The way you invoke the MySQL.java. may be the cause of the problem.
As from your implementation, your MySQL.java seems to be a plain java application. However, it seems that you are trying to treat MySQL .java as a servlet.
My guess this that you wanted to do something like this:
class MySQL extends HttpServlet {
     public void doPost(..... ) {
          //the codes in the main method to be put in this method.
     public void doGet( ....) {
             doPost(....)
     //some of your other methods put here.
}For more information on how to write a servlet, you may visit http://java.sun.com/developer/onlineTraining/Programming/BasicJava1/servlet.html