Page 2 - Wml With Servlets .. Does It Work?

req.getParameter() can return null if any of the parameters do not exist. Check if the names used are correct.

Also, I would recommend writing the code a little more robust. Example:


A proper null reference checking will ensure that you don't get NullPointerException.



Sorry, no.

I am not getting nullpointerexception for the program but it says cannot load servlet. Is the insert into statements correct?? I am sorry for asking your mail id. I thought i can clarify my doubts. anyway sorry.

Could you print the stack trace from your program and post it here?

This is the stack trace i got in my program


Nov 26, 2007 10:32:31 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet RegisterServlet threw exception
java.lang.NullPointerException
at RegisterServlet.doGet(RegisterServlet.java:30)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:868)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProt ocol.java:663)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Unknown Source)

If the actual line numbers in your code are the same as what you posted, you are getting a NullPointerException around where I thought it would be -


I recommend that you modify your code to check for the null reference, as suggested earlier.

import java.io.*;
import java.sql.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;


import javax.servlet.*;
import javax.servlet.http.*;

public class RegisterServlet extends HttpServlet
{

public void doGet(HttpServletRequest req, HttpServletResponse res)throws ServletException, IOException

{
Connection con = null;
Statement stmt = null;
ResultSet rs = null;
PreparedStatement ps = null;


res.setContentType("text/vnd.wap.wml");
PrintWriter out = res.getWriter();

out.println("<?xml version=\"1.0\"?>");
out.println("<!DOCTYPE wml PUBLIC " + "\"-//WAPFORUM//DTD WML 1.1//EN\" "
+ "\"http://www.wapforum.org/DTD/wml_1.1.xml\">");

out.println("<wml>");
out.println("<card id=\"new\" title=\"Register\">");
out.println(" <p> Login </p>");


try {


Class.forName("oracle.jdbc.driver.OracleDriver");


con = DriverManager.getConnection("jdbcracle:thin:@rccadv33:1521rcl", "scott", "tiger");
stmt = con.createStatement();

String str = "insert into login values(?,?)";
ps = con.prepareStatement(str);

String username3=req.getParameter("name");
String password3=req.getParameter("pswd");
String confirmpassword3=req.getParameter("confirmpswd");

ps.setString(1, username3);
ps.setString(2, password3) ;

ps.executeUpdate();

res.sendRedirect("registrationsuccess.wml");
// show that the new account has been created
out.println(" Hello : ");
out.println(" '"+username3+"'");
ps.close();

}

catch (IOException e) {

// you handle the exception here
e.printStackTrace();

}

catch(ClassNotFoundException e)
{
out.println("Couldn't load database driver: " + e.getMessage());
out.println("hi");
}

catch(SQLException e)
{
out.println("SQLException caught is: " + e.getMessage());
out.println("<p>hi</p>");
out.println("</card>");
out.println("</wml>");
}

finally {

try {
if (con != null) con.close();
}
catch (SQLException ignored) { }
}


}
}


Now i am getting another strange problem, the null values are getting inserted into database. I am passing parameters correctly know? Can you please modify my code so that i can correctly insert the values into database.