BlackBerry Forums Support Community - Push a new screen on a menu item select

Guys i am very new to the world of blackberry. I have one question now. I have created a small application where i will have a MAIN screen displaying some components. But when the user presses the menu and select a menu option i need to push another screen containing different set of components.My sample code is as follows

Code:



public class ContactMain extends UiApplication {
 

        public static void main(String[] args) {
 

                ContactMain contactMain = new ContactMain();

                contactMain.enterEventDispatcher();

        }
 

        public ContactMain() {

                pushScreen(new ContactMainScreen());

        }
 

}
 
 

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

final class ContactMainScreen extends MainScreen {
 

        //components declaration
 
 

        public ContactMainScreen() {
 

          //initialize components
 

        }
 

        protected void makeMenu(Menu menu, int instance) {

                menu.add(addContact);

                

        }
 

        private MenuItem addContact = new MenuItem("Add Contact", 110, 10)                      

        {

                public void run() {

                        UiApplication.getUiApplication().(new ContactAddScreen());

                }

        };
 

}
 
 
 

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

final class ContactAddScreen extends MainScreen {
 
 

        //components declaration
 

        public ContactAddScreen() {
 

                    //initialize components
 

        }

}

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

But as soon as i press the menu i am getting a null pointer exception .

please help