ServletTestRunner

 import java.io.*;
 import java.util.*;
 import javax.servlet.*;

 public class HelloWorldServlet extends GenericServlet { 
    static String initName;
    static String initAge;

    public void init(ServletConfig sc) throws ServletException {
       super.init(sc);
       initName=sc.getInitParameter("name");
       initAge=sc.getInitParameter("age");
    }

    public void service(ServletRequest req, ServletResponse res)
    throws ServletException, IOException {
       PrintWriter toClient=res.getWriter();
       String name=req.getParameter("name");
       String age=req.getParameter("age");
       toClient.println("Welcome to HelloWorldServlet.");
       toClient.println("Your name is "+(name!=null ? name : initName));
       toClient.println("You're "+(age!=null ? age : initAge)+"years old");
       toClient.close();
    }
 }