apache tomcat error

hey when i try to submit my jsp page in order to access another jsp page i'm getting the following error:

description: The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:510)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:368)

root cause

java.lang.NullPointerException
hospital_administration_system.login.authenticate(login.java:45)
org.apache.jsp.validateuser_jsp._jspService(validateuser_jsp.java:77)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:368)

this id some of my code:

login.java class:

package hospital_administration_system;
import java.sql.*;
import java.io.*;

public class login {

public login() {
}
//method for the database connection
public Connection getConnection()
throws IOException{
Connection conn = null;
try{
DBConnectionManager manager = DBConnectionManager.getInstance();
conn = DriverManager.getConnection("HOSPITALdb");
} catch(SQLException e) {
System.out.println("SQLException: " + e.getMessage());
while((e = e.getNextException()) != null)
System.out.println(e.getMessage());
}
return conn;
}

//method that is called from validateuser.jsp and this checks for the authentic user and password
public boolean authenticate(String user, String password)
throws SQLException, IOException{
String userName = null, passWord = null;
login dbconn = new login();
Statement stmt = dbconn.getConnection().createStatement();
String sql = "SELECT USER_NAME, PASSWORD FROM LOGIN WHERE USER_NAME='" + user + "'" + "AND PASSWORD='" + password + "'";
ResultSet rs = stmt.executeQuery(sql);
if(rs.next()){
userName = rs.getString("USER_NAME");
passWord = rs.getString("PASS_WORD");
}
if(userName != null && passWord != null && user.equals(userName) && password.equals(passWord)){
return true;
} else return false;
}
}

validateuser.jsp class:

<%@page contentType="text/html"%>
<%@page pageEncoding="UTF-8"%>
<%@page import="java.util.*" %>
<jsp:useBean id="idHandler" class="hospital_administration_system.login" scope="request">
<jsp:setProperty name="idHandler" property="*"/>
</jsp:useBean>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<%
String userName = request.getParameter("userName");
String passWord = request.getParameter("passWord");
if (idHandler.authenticate(userName, passWord)){
response.sendRedirect("home.jsp");
} else {
response.sendRedirect("login.jsp");
}
%>
</body>
</html>

Any help would be great
Thanks

From the stack trace:

hospital_administration_system.login.authenticate(login.java:45)

So you're getting an NPE at line 45 of login.java. What's at that line? Why is something null that shouldn't be?

And please use UBB Code tags when posting code.
[ February 08, 2007: Message edited by: Bear Bibeault ]

line 45 in login.java is as follows:

any ideas?

The only way that statement can NPE is if the getConnection() method returns null.

Time to dig in, backtrack and diagnose why that's happening.

Hello poster , I have meet this trouble . I also dislike it . And afraid so many error displayed .