c# - Cross-thread operation not valid ListView

Question

I'm trying use thread to leech link from website, but when i trying run . It show error:

Cross-thread operation not valid: Control 'listView1' accessed from a thread other than the thread it was created on

My code:

try
{
    foreach (HtmlNode node in (IEnumerable<HtmlNode>)document.DocumentNode.SelectNodes("//table[@class='tbl' and @id='stats']//tr[@class='' or @class='bg']"))
    {
    HtmlAgilityPack.HtmlDocument document2 = new HtmlAgilityPack.HtmlDocument();
    document2.LoadHtml(node.InnerHtml);
    try
    {
    string str6 = document2.DocumentNode.SelectSingleNode("//td[2]//a").Attributes["href"].Value;
    string innerText = document2.DocumentNode.SelectSingleNode("//td[2]//a").InnerText;
    string[] items = new string[] { listView1.Items.Count + 1.ToString(), innerText, str6, "" };
    ListViewItem item = new ListViewItem(items);
    listView1.Items.Add(item);
    listView1.EnsureVisible(listView1.Items.Count - 1);
    }
    catch (Exception ex)
    {
    MessageBox.Show(ex.Message);
    }
    }
}
catch (Exception ex)
{
    MessageBox.Show(ex.Message);
}

You don't need to add it. It is already there. In your listview. Basically it tells you if you can go on or if you need to marshall your call to the GUI thread (STAThread...). You can do something like: ``if( this.InvokeRequired ) { this.Invoke(...) }`` Cannot remember exact syntax for invoke as I did no C# in ages. — BitTickler, Apr 23 '16 at 03:34

Nitin · Accepted Answer · 2016-04-23T03:37:59.983

5

This is because of Thread affinity of controls. Those can be updated only on thread they were created. InvokeRequired and Invoke gives method to update the control on same thread:

        if (listView1.InvokeRequired)
        {
            listView1.Invoke((MethodInvoker) delegate()
            {
                ListViewItem item = new ListViewItem(items);
                listView1.Items.Add(item);
                listView1.EnsureVisible(listView1.Items.Count - 1); 
            });
        }

edited Apr 23 '16 at 03:37

answered Apr 23 '16 at 03:36

Nitin

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There there. I think I last used this before lambdas were added ;) But usually to avoid duplicated code, I did it with an else and the actual code on the listview defined outside once. – BitTickler Apr 23 '16 at 03:37
1

Low quality answer compared to hundreds of existing duplicates of this question. If you going for canonical post make sure to put at least some effort – Alexei Levenkov Apr 23 '16 at 03:41

c# - Cross-thread operation not valid ListView

1 Answers1