A. HttpSession session = request.getSession(true); int ival = session.getAttribute("counter"); if(ival == null){ ival = 1; }else{ Ival = ival + 1; } session.setAttribute ("counter", ival)

B. HttpSession session = request.getSession (true); Integer ival = (Integer) session.getAttribute ("counter"); Session.setAttribute ("counter", ival + 1)

C. HttpSession session = request.getSession (true); Integer ival = (Integer) session.getAttribute ("counter"); if(ival == null){ Ival = new Integer (1); } else { Ival = new Integer (ival.intValue () + 1); } session.setAttribute ("counter", ival)

D. HttpSession session = request.getSession (); int ival = session.getAttribute("counter"); if (ival == null){ ival = 1; } else { ival = ival + 1; }session.setAttribute ("counter", new Integer (ival))