Question

I am having trouble populating a datagridview with items from a string array. Here is the code I used to call the function:

ThreadPool.QueueUserWorkItem((o) => 
                ReBuildObjectExplorer();

And the function itself:

        try
        {
            List<ExplorerItem> list = new List<ExplorerItem>();
            var item = new ExplorerItem();

            for (int i = 0; i < lbl.Length; i++) // lbl = string array with items
            {
                item.title = lbl[i].Name;
                list.Add(item);
            }

            BeginInvoke((MethodInvoker)delegate
            {
                explorerList = list;
                dgvObjectExplorer.RowCount = explorerList.Count;
                dgvObjectExplorer.Invalidate();
            }); 
        }
        catch (Exception e) { MessageBox.Show(e.ToString(); }

The problem is: Suppose there are 76 items in the array. When I use this code, it ALWAYS adds the 75th item 76 times and nothing else. Why does this happen? I can’t seem to figure out what is wrong with my code.

Answer 1

I think you want:

    try
    {
        List<ExplorerItem> list = new List<ExplorerItem>();

        for (int i = 0; i < lbl.Length; i++) // lbl = string array with items
        {
            var item = new ExplorerItem();
            item.title = lbl[i].Name;
            list.Add(item);
        }

        BeginInvoke((MethodInvoker)delegate
        {
            explorerList = list;
            dgvObjectExplorer.RowCount = explorerList.Count;
            dgvObjectExplorer.Invalidate();
        }); 
    }
    catch (Exception e) { MessageBox.Show(e.ToString(); }

That is, move the creation of the new ExplorerItem inside the loop rather than outside it. That way a new item is created at each iteration of the loop. If you don’t create a new item in each iteration, then you are adding the same item over and over again, changing its title in every iteration.