public static QuanLyNhom GetFromFile(string pathDataFile, string tennhom)
        {
            List <QuanLyNhom> arrayLines = QuanLyNhom.GetListFromFile(pathDataFile);

            foreach (var nhom in arrayLines)
            {
                if (String.Compare(nhom.TenNhom, tennhom, true) == 0)
                {
                    return(nhom);
                }
            }
            return(null);
        }
        public static void XoaNhom(string pathDataFile, string tennhom)
        {
            List <QuanLyNhom> listNhom = QuanLyNhom.GetListFromFile(pathDataFile);
            List <QuanLyNhom> ketQua   = new List <QuanLyNhom>();

            foreach (var nhom in listNhom)
            {
                if (string.Compare(nhom.TenNhom, tennhom) != 0)
                {
                    ketQua.Add(nhom);
                }
            }
            using (StreamWriter sw = new StreamWriter("C:/Users/VTA/Documents/Visual Studio 2015/Projects/QuanLyDaBa/QuanLyDaBa/Data/Nhom.txt"))
            {
                foreach (var x in ketQua)
                {
                    sw.WriteLine(x.TenNhom);
                }
                MessageBox.Show("Xóa nhóm thành công", "Thông Báo", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
        }