//modify the carinfo
        private void ModifyCarinfoClick(object sender, RoutedEventArgs e)
        {
            DataManager ins = DataManager.createInstance();
            Carinfo c = (Carinfo)this.CarList.SelectedItem;
            if (c == null)
            {
                System.Windows.MessageBox.Show("请选择后再修改", "提示", System.Windows.MessageBoxButton.OK);
                return;
            }

            addCar cw = new addCar(true, c);
            cw.Owner = this;

            if (cw.ShowDialog() ?? false)
            {
                ObservableCollection<Carinfo> cns = (ObservableCollection<Carinfo>)this.CarList.ItemsSource;
                int index = cns.IndexOf(c);
                cns.Remove(c);

                c = (Carinfo)cw.Thecar;

                this.DisplayCarID.Text = c.CarID;
                this.DisplayCarInsurance.Text = c.Insurancedate;
                this.DisplayCarPurchaseTime.Text = c.Purchasetime;
                this.DisplayCarRemark.Text = c.Remark;
                this.DisplayCarStatus.Text = c.Status;
                this.DisplayCarstyle.Text = c.Carstyle;
                this.DisplayLastCheck.Text = c.Latestchecktime;

                cns.Insert(index, c);
                //this.CitizenList.ItemsSource
            }
        }
        //add car
        private void AddCarinfoClick(object sender, RoutedEventArgs e)
        {
            addCar cw = new addCar(false, new Carinfo());
            cw.Owner = this;

            if (cw.ShowDialog() ?? false)
            {
                ObservableCollection<Carinfo> cns = (ObservableCollection<Carinfo>)this.CarList.ItemsSource;

                if (cns == null)
                {
                    cns = new ObservableCollection<Carinfo>();
                }

                Carinfo c = (Carinfo)cw.Thecar;
                cns.Add(c);
                this.CarList.ItemsSource = cns;
            }
        }