Strange issue with a datagridview and a tabcontrol C#

问题

I have a strange problem. I have a TabControl with two TabPages. Each page has a datagridview. Both datagridviews are populated with XML files.

I want to have the AutoSizeColumnsMode set to "Fill" for both DataGridViews. I want to set the width of columns in my code.

And everything works fine for the TabPage1 but setting width for the DataGridView on TabPage2 throws the NullReferenceException.

I really don't get it because I do the same thing as for datagridview1 and there works fine but datagridview2 throws the exception. Additionally, there is no exception if I choose any AutoSizeColumnsMode value but Fill.

Here's the code:

        XmlReader xmlFile = XmlReader.Create("File1.xml", new XmlReaderSettings());
        DataSet ds = new DataSet();
        ds.ReadXml(xmlFile);



            dataGridView1.DataSource = ds.Tables[0];
            dataGridView1.Sort(dataGridView1.Columns[1], ListSortDirection.Ascending);

           dataGridView1.Columns[0].Width = 35;
            dataGridView1.Columns[1].Width = 248;
            dataGridView1.Columns[2].Width = 110;
            dataGridView1.Columns[3].Width = 140;
            dataGridView1.Columns[9].Width = 127;
            dataGridView1.Columns[0].Visible = false;
            dataGridView1.Columns[1].Visible = true;
            dataGridView1.Columns[2].Visible = true;
            dataGridView1.Columns[3].Visible = true;
            dataGridView1.Columns[4].Visible = false;
            dataGridView1.Columns[5].Visible = false;
            dataGridView1.Columns[6].Visible = false;
            dataGridView1.Columns[7].Visible = false;
            dataGridView1.Columns[8].Visible = false;
            dataGridView1.Columns[9].Visible = true;
            dataGridView1.Columns[10].Visible = true;
            dataGridView1.Columns[10].Width = 100;

            xmlFile.Close();

        XmlReader xmlFile2= XmlReader.Create("File2.xml", new XmlReaderSettings());
        DataSet ds2 = new DataSet();
        ds2.ReadXml(xmlFile2);
        dataGridView2.DataSource = ds2.Tables[0];


            dataGridView2.Columns[0].Width = 135; // The exception is thrown here
            dataGridView2.Columns[9].Width = 200;
            dataGridView2.Columns[8].Width = 300;
            dataGridView2.Columns[7].Width = 70;
            dataGridView2.Columns[6].Width = 70;
            dataGridView2.Columns[5].Width = 124;
            dataGridView2.Columns[4].Width = 81;
            dataGridView2.Columns[3].Width = 70;
            dataGridView2.Columns[2].Width = 70;
            dataGridView2.Columns[1].Width = 124;

            dataGridView2.Columns[0].Visible = true;
            dataGridView2.Columns[1].Visible = true;

            dataGridView2.Columns[2].Visible = true;
            dataGridView2.Columns[3].Visible = true;
            dataGridView2.Columns[4].Visible = true;

            dataGridView2.Columns[5].Visible = false;
            dataGridView2.Columns[6].Visible = false;
            dataGridView2.Columns[7].Visible = false;
            dataGridView2.Columns[9].Visible = false;


            xmlFile2.Close();

回答1:

This is because a data-bound control(dataGridView2) is not updated until the control is made visible. See this. You can refresh the binding, for example, by programmatically switching to TabPage2 and back to the first tab.

回答2:

THe only thing I can se at the moment is that you are not doing this on tabpage 2

dataGridView1.Sort(dataGridView1.Columns[1], ListSortDirection.Ascending);

try

dataGridView2.Sort(dataGridView2.Columns[1], ListSortDirection.Ascending);

来源：https://stackoverflow.com/questions/17030531/strange-issue-with-a-datagridview-and-a-tabcontrol-c-sharp

标签

datagridview

tabcontrol