从列表视图和xamarin.android中的数据库中检测记录

Question

我想从列表视图中删除记录。所以我使用长按。如果用户输入yes，则必须长按一个对话框，然后删除该记录。如果用户按下否按钮则关闭。 deleterecord方法正在执行但未执行任何操作。

public class ListActivity : Activity
{
    ListView listItems;

    protected override void OnCreate (Bundle SaveInstace)
    {
        base.OnCreate (SaveInstace);

        SetContentView (Resource.Layout.Listviewlayout);

        //back button
        ActionBar.SetDisplayHomeAsUpEnabled (true);
        //Gets ListView object instance
        Database sqldb1 = ((GlobalClass)this.Application).sqldb;

        listItems = FindViewById<ListView> (Resource.Id.listView1);

        GetCursorView ();
        //Add ItemClick event handler to ListView instance
        listItems.ItemClick += new EventHandler<AdapterView.ItemClickEventArgs> (item_Clicked);

        listItems.ItemLongClick+= new EventHandler<AdapterView.ItemLongClickEventArgs> (item_longclicked);

    }

my item_clicked方法就在这里..

    public void item_longclicked(object sender,AdapterView.ItemLongClickEventArgs e)
    {
        Database sqldb1 = ((GlobalClass)this.Application).sqldb;
        TextView shName = e.View.FindViewById<TextView> (Resource.Id.Name_row);
        TextView shLastName = e.View.FindViewById<TextView> (Resource.Id.LastName_row);
        TextView shAge = e.View.FindViewById<TextView> (Resource.Id.Age_row);
        int s=e.Position;
        AlertDialog.Builder alert = new AlertDialog.Builder (this);
        alert.SetTitle ("Do you want to delete");
        alert.SetPositiveButton ("yes", (EventHandler<DialogClickEventArgs>)null);
        alert.SetNegativeButton ("No", (EventHandler<DialogClickEventArgs>)null);
        var dial = alert.Create ();
        dial.Show ();

        //get the buttons
        var yesbtn= dial.GetButton((int)DialogButtonType.Positive);
        var nobtn = dial.GetButton ((int)DialogButtonType.Negative);
        yesbtn.Click+=delegate 
        {
            sqldb1.DeleteRecord(s);
            GetCursorView();
        };
    }