stefano bertozzi [http://community.jboss.org/people/bertoz84] created the discussion
"ERROR [STDERR] java.lang.NullPointerException - can't solve" To view the discussion, visit: http://community.jboss.org/message/600753#600753 -------------------------------------------------------------- Hi all, i really need help to overcome this error. I'm going to paste the interesting parts of my code: *TEST BEAN ( we are inside a method called by the java test client ):* * .* * .* * . * try { System.out.println("lowering the amount of the selected book"); Book abook = (Book) bookop.findByISBN(80002).get(0); // Book is an entity bean --- bookop is the istance of a session bean that performs // operations on Book *bookop.updateMin*(abook.getISBN(), 2); // tot - 2 // OPERATION updateMin *DONE* SUCCESSFULLY } catch (Exception e) { e.printStackTrace(); } Users an_user = (Users) user.findByUser("mouse").get(0); // Users is an entity bean --- user is the istance of a session bean that performs // operations on Users *cart.checkoutCart*(an_user); // cart is the istance of a session statefull bean that performs classic operations like in a web site ( bookshop ) // to see what this method go down -end *CART BEAN ( the called method ):* * * public void *checkoutCart*(Users customer) { for (int i = 0; i < books.size(); i++) // where books is: private List<CartBook> books , a simple class made up of a Book and the quantity // to purchase of that book { Book abook = books.get(i).getBook(); Integer quantity = books.get(i).getQuantity(); try { System.out.println("lowering the amount of the selected book"); *DBOperation.updateMin*(abook.getISBN(), quantity); // DBOperation is the same as bookop seen before // ERROR [STDERR] java.lang.NullPointerException } catch (Exception e) { e.printStackTrace(); } } } -end so basically the code is the same; the difference is that going through the cart bean i can lower the quantity of a list of books ( that are the books that a customer puts in his cart: when he performs a checkout operation the method updateMin lowers the amount of every books purchased in the store ) instead of only one. the problem is that through the cart i get always the ERROR [STDERR] java.lang.NullPointerException in the *DBOperation.updateMin* methods that is exactly the same of *bookop.updateMin*. Every cicle of the for( ) command i get this error. I can assure that my list is not empty and abook & quantity are not null. I really don't get the problem! Thank you in advance!! -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/600753#600753] Start a new discussion in EJB3 at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&containerType=14&container=2029]
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