Concurring Java Problem..Please Help

[doflynn]

When I run my java application this error keeps coming up when trying to log in. Yer help would be much appreciated

HTTP Status 500 -
--------------------------------------------------------------------------------

type Exception report

message

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

exception

org.apache.jasper.JasperException: Exception in JSP: /HeadNPass.jsp:19

16:
17:
18: NurseDao da = new NurseDao();
19: Nurse n = da.getNurse(userName);
20:
21: if(n != null)
22: {

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handle JspException(JspServletWrapper.java:504)
org.apache.jasper.servlet.JspServletWrapper.servic e(JspServletWrapper.java:393)
org.apache.jasper.servlet.JspServlet.serviceJspFil e(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspSe rvlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet .java:802)
org.netbeans.modules.web.monitor.server.MonitorFil ter.doFilter(MonitorFilter.java:368)


root cause

java.lang.NullPointerException
hospital.NurseDao.getNurse(NurseDao.java:324)
org.apache.jsp.HeadNPass_jsp._jspService(HeadNPass _jsp.java:63)
org.apache.jasper.runtime.HttpJspBase.service(Http JspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet .java:802)
org.apache.jasper.servlet.JspServletWrapper.servic e(JspServletWrapper.java:332)
org.apache.jasper.servlet.JspServlet.serviceJspFil e(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspSe rvlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet .java:802)
org.netbeans.modules.web.monitor.server.MonitorFil ter.doFilter(MonitorFilter.java:368)




--------------------------------------------------------------------------------

The code is as follows:


String userName = request.getParameter("username");
String password = request.getParameter("password");


if ((userName != null) && (password != null)){


NurseDao da = new NurseDao();
Nurse n = da.getNurse(userName);

if(n != null)
{
int pw = Integer.parseInt(password);
if(n.getStaffId() == pw)
{
request.getSession(true).setAttribute("HEADNURSE", n);
response.sendRedirect("HeadNurse.jsp");
}
else
{
response.sendRedirect("error.jsp");
}
}
else
{
response.sendRedirect("error.jsp");
}

[wsaryada]

root cause

java.lang.NullPointerException
hospital.NurseDao.getNurse(NurseDao.java:324)

Base on the error message above can you tell us what is on the 324 line of your NurseDao.java, because this line cause the NPE in your program.

[doflynn]

Thanks a million for your reply.

Line 324 consisted of this block of code:

try{


DBConnectionManager manager = DBConnectionManager.getInstance();
con = manager.getConnection("hospitaldb");

Line 324: Statement stmt = con.createStatement();
ResultSet results = stmt.executeQuery ("Select * from Nurse where surname = '" + strUN + "'");


while (results.next()){
Nurse = new Nurse();
Nurse.setStaffId(results.getInt("NurseID"));
Nurse.setWardId(results.getInt("WardId"));
Nurse.setFirstName(results.getString("FirstName")) ;
Nurse.setSurname(results.getString("Surname"));
Nurse.setAddress(results.getString("Address"));
Nurse.setContactNumber(results.getString("ContactN umber"));


}

stmt.close();
con.close();

[wsaryada]

Ok then. The only thing that could throw the NPE is the connection object. Have you check whether the DBConnectionManager class returning a valid connection object? If it fails to create the connection object, the connection is null, and when you try to create an instance of statement from it and NPE is thrown.