C# datatable, get NullReferenceException on Clear

Question

i need help to understand why i get this error on a line in my code an not at a line where i would expect it.

I have a datatable object which i fill from a oracle select. After this i use this datatable as datasource for a datagridview. All fine.

I put all togehter in a methode to call it frequently from a timer.

    void fill_dgrsessions()
    {
        if (lst_connected.SelectedIndex >= 0)
        {

            dt_aktsessions.Clear();
            dt_aktsessions = l_dbconn[lst_connected.SelectedIndex].get_sessiondata();
            dgrsessions.DataSource = dt_aktsessions;
            lbl_sessions_title.Text = "Sessions in der DB: " + l_dbconn[lst_connected.SelectedIndex].get_dbname();
        }
        else
        {
            MessageBox.Show("Keine der aktiven DB's ausgewählt!");
            chkbox_autorefresh.Checked = false;
        }
    }

When the target DB goes offline, i get the error in the line

dt_aktsessions.Clear();

why? I would expect this error in line:

dt_aktsessions = l_dbconn[lst_connected.SelectedIndex].get_sessiondata();

Thanks for your time and advices.

Marcel

where have you declared this variable dt_aktsessions? – Hameed Syed Jul 05 '18 at 07:38 — Hameed Syed, Jul 05 '18 at 07:38
this is a global variable in the class – MarcelS Jul 05 '18 at 07:44 — MarcelS, Jul 05 '18 at 07:44
Its not accessible or you haven't initialized. – Hameed Syed Jul 05 '18 at 07:49 — Hameed Syed, Jul 05 '18 at 07:49

C# datatable, get NullReferenceException on Clear

0 Answers0