What is the corrext syntax for session.getAttribute? I am having an error pop up for "add" for both of these lines. Is there something im missing?

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

HttpSession session = request.getSession();

int FilmID = Integer.parseInt(request.getParameter("film_id"));

int price = 1;

//session.setAttribute("film",Cart);

session.setAttribute("price", price);

session.getAttribute("cart").add(price);

cart.add(FilmID); // adds the film to the cart associated with the session.

session.getAttribute("cart").add(FilmID); // adds the film to the cart associated with the session.

request.getRequestDispatcher("ShoppingCart.jsp").forward(request, response);

}