public static void Chon(ArrayList arrayList)
        {
            int chon;

            while (true)
            {
                Menu();
                chon = int.Parse(Console.ReadLine());
                Console.Clear();
                if (chon == 6)
                {
                    break;
                }
                switch (chon)
                {
                case 1:
                    MatHang_BLL.NhapTT(arrayList);
                    MatHang_DAL.GhiFile(arrayList);
                    Console.ReadKey();
                    Console.Clear();
                    break;

                case 2:
                    MatHang_BLL.HienAll(arrayList);
                    Console.ReadKey();
                    Console.Clear();
                    break;

                case 3:
                    MatHang_BLL.HienAll(arrayList);
                    MatHang_BLL.TimKiem(arrayList);
                    Console.ReadKey();
                    Console.Clear();
                    break;

                case 4:
                    MatHang_BLL.HienAll(arrayList);
                    MatHang_BLL.Sua(arrayList);
                    MatHang_DAL.GhiFile(arrayList);
                    Console.ReadKey();
                    Console.Clear();
                    break;

                case 5:
                    MatHang_BLL.HienAll(arrayList);
                    MatHang_BLL.Xoa(arrayList);
                    MatHang_DAL.GhiFile(arrayList);
                    Console.ReadKey();
                    Console.Clear();
                    break;

                default: break;
                }
            }
        }
        public static void Run()
        {
            int chon;

            while (true)
            {
                Menu();
                chon = int.Parse(Console.ReadLine());
                Console.Clear();
                if (chon == 6)
                {
                    break;
                }
                switch (chon)
                {
                case 1:
                    MatHang_DAL.DocFile(mathang);
                    MatHang_GUI.Chon(mathang);
                    break;

                case 2:
                    NhanVien_DAL.DocFile(nhanvien);
                    NhanVien_GUI.Chon(nhanvien);
                    break;

                case 3:
                    GiaBan_DAL.DocFile(giaban);
                    GiaBan_GUI.Chon(giaban);
                    break;

                case 4:
                    HoaDon_DAL.DocFile(hoadon);
                    HoaDon_GUI.Chon(hoadon);
                    break;

                case 5:
                    BaoCaoThongKe_DAL.DocFile(thongke);
                    BaoCaoThongKe_GUI.Chon(thongke);
                    break;

                default: break;
                }
            }
        }