Forum:

Servlets

problem in retriving List objects

Greenhorn

Posts: 6

posted 10 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

Hello, i am trying to print values in a jsp page Customer.jsp taken from AccountDetailDAO. At first page goes through LoginValidation but i am getting NullPointerException in line 83.
It works fine when i am login as a manager.
Here are the relevant codes
LoginValidation.java

if(user=="" || pass=="")
			{
				out.println("Username or password cannot be empty");
				rd=request.getRequestDispatcher("LogIn.jsp");
				rd.include(request, response);
			}
			else
			{
			st=conn.prepareStatement("select role from login where username=? and password=?");
			st.setString(1, user);
			st.setString(2, pass);
			rs=st.executeQuery();
			if(rs.next())
			{
				role=rs.getString(1);
				sess.setAttribute("role",role);
				sess.setAttribute("user",user);
				sess.setAttribute("pass",pass);
				if(role.equals("customer"))
				{
					dao.getConnection();
					List<AccountDetail> actdtl=dao.getAccountno();
					request.setAttribute("accountno", actdtl);
					
					rd=request.getRequestDispatcher("Customer.jsp");
					rd.forward(request, response);                                       //Line 83
					
				}
				else if(role.equals("manager"))
				{
					rd=request.getRequestDispatcher("Manager.jsp");
					rd.forward(request, response);
				}
						}
			else{
				out.println("Wrong username or password. LogIn again");
				rd=request.getRequestDispatcher("LogIn.jsp");
				rd.include(request, response);
			}
			}

Customer.jsp

AccountDetailDAO

Jeanne Boyarsky

author & internet detective

Posts: 41878

909

I like...

posted 10 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

Which line is line 83?

[OCP 17 book] | [OCP 11 book] | [OCA 8 book] [OCP 8 book] [Practice tests book] [Blog] [JavaRanch FAQ] [How To Ask Questions] [Book Promos]
Other Certs: SCEA Part 1, Part 2 & 3, Core Spring 3, TOGAF part 1 and part 2

Java 8 (verified skill)
Skill verified by Jeanne Boyarsky

JUnit 5 (verified skill)
Skill verified by Jeanne Boyarsky

Amit Kumar Thakur

Greenhorn

Posts: 6

posted 10 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

I have already marked that in LoginValidaion.java .

Avinash venna

Greenhorn

Posts: 17

posted 10 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

the getDispatcher method takes path as an argument. most probably the path here is wrong. Try checking that.. you may try /Customer.jsp

Alex Theedom

Author

Posts: 116

I like...

posted 10 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

A null pointer will occur if a method is called on an object that is null and according to the API doc the getRequestDispatcher() method "returns null if the servlet container cannot return a RequestDispatcher".

I attempted to replicate this in my environment without success. I am using Tomcat 7 and if the path argument in the getRequestDispatcher() is not valid it does not throw a null pointer exception, instead the servlet sends an HTTP 404 message code to the browser.

Investigating this further I found this post by Charles Lyons that talks in detail about this: https://coderanch.com/t/453276/java-Web-Component-SCWCD/certification/RequestDispatcher-null-outcome. It appears that server implementation determines the behaviour.

Would you post the stack trace if correcting the path does not solve it.

Alex Theedom. Author of: Java EE Video Courses (JAX-RS, Bean Validation, Websocket, JSON-P and much more), Java EE 8: Only What's New
and Professional Java EE Design Patterns. Blogger at readlearncode.com. Twitter @alextheedom

Not so fast naughty spawn! I want you to know about

a bit of art, as a gift, that will fit in a stocking

https://gardener-gift.com