Whats wrong with this servlet code..?no error in log

Question

hello guys..hope one of you can help....
i have 2 servlet classes. one receives form data sent from a jsp page, then create a form object containing all the inputs.. that object is then added to the session ..
also, it construct a User object containing info about the present user and add it to the session.. IUser and Form are inner to the main class.
the first servlet (check) seems to work fine.. but the problem occurs with the second servlet...i have inserted some printl statements to help me identify how far it goes and it seems that the whole code of the second servlet(update) is almost redundant....I dont get any error message ..simply a blank page which is of course of no help to me...
I hate inserting long code here but i would be pleased if anyone could tell me of a way to find out about the actual problem..program compiles fine but..it just freezes at runtime
..here is part of the code..whats wrong?
HttpSession session=request.getSession();
     User user2=(User)session.getAttribute("person");
     Form fr=(Form)session.getAttribute("form");
     System.out.println("User and Form created");
     int uid=user2.getId(); //class User contain the getId method
     String uname=user2.getName();
     System.out.println("Data for user retrieved");
     String goTo=fr.getC();
     String password = fr.getP();
String email=fr.getE();
String newName=fr.getN();
System.out.println("data from form retrieved");
thanks

Answer 1

the first servlet was indeed supposed to ass all those attributes...
but the thing is that the data being retrieved later were not of the type expected...
i have now decided to proceed differently but I am a bit curious to lean more about something that you mentionned in relation to servlet listeners..i never thought of the need to remove all those attribute when the session times out...
I thought that it was doned automatically with a call to session.invalidate().
is that not the case?
thanks