public void Start(OrderService a) { bool Y = true; while (Y) { Console.WriteLine("请输入:1.添加订单 2.删除订单 3.更改订单 4.查找订单 5.完成订单"); string n = Console.ReadLine(); switch (n) { case "1": a.Add(); break; case "2": a.Delete(); break; case "3": a.Change(); break; case "4": a.Find(); break; case "5": Y = false; break; default: Console.WriteLine("无效操作"); break; } } }