protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        int num = Integer.valueOf(request.getParameter("num"));
        List<Student> data = new ArrayList<>();
        List<String> setCode = createCode(num);
        Random r = new Random();
        char[] c = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L'};

        for (int i = 0; i < num; i++) {
            Student s = new Student();
            s.setCode(setCode.get(i));
            boolean b = r.nextBoolean();
            String name = (b ? "Mr " : "Miss ") + c[r.nextInt(12)];
            s.setName(name);
            s.setGender(b ? "male" : "female");
            s.setMark(r.nextInt(11));
            data.add(s);
        }
        request.setAttribute("data", data);
        request.getRequestDispatcher("List.jsp").forward(request, response);
    }