public static String doAddCart(int qty, int medicineId, int userId) { Cart cp = CartHandler.getCartMedicine(medicineId, userId); int medicineStock = MedicineHandler.getMedicineById(medicineId).Stock; if (qty < 1) { return("Qty must be more than 0"); } if (cp == null) { if (qty > medicineStock) { return("Qty can't be more than available stock"); } CartHandler.createCartMedicine(userId, medicineId, qty); return(""); } else { int currCartStock = cp.Quantity; int requetedStock = currCartStock + qty; if (requetedStock > medicineStock) { return("Qty must be less than or equals to medicine stocks"); } CartHandler.updateCartMedicineQty(medicineId, userId, requetedStock); return(""); } }