Code before foreach loop does not execute.

Question

Yay I finally thought of a title!

I have a foreach loop that iterates the ListViewItems and does something with each item. But the problem is not that it doesn't do the work in the loop, but it simply does not execute any code that appears before the foreach loop.

Below is the full method:

    private void pNGToolStripMenuItem_Click(object sender, EventArgs e)
    {
            stat.Text = "Converting to PNG.";
            _piclist.Enabled = false;

            foreach (ListViewItem item in _piclist.Items)
            {
                try
                {
                    /* magical image conversion here. */
                   _piclist.Enabled = true;
                       stat.Text =
                          "Conversion comlpete.";

                }
                catch (Exception exception)
                {
                    stat.Text =
                        exception.Message;

                }
            }
    }

Can somebody please help me understand why the code:

stat.Text = "Converting to PNG.";
            _piclist.Enabled = false;

before the foreach loop never gets executed?

Thanks

Answer 1

Sounds like you haven't registered the handler with the event... (+=)

Martin

Ps. To clarify - I'm saying that the entire method doesn't get called because I suspect you haven't got this handler registered for the event...

Answer 2

It does. The thing is that body of your loop immediately overwrites the results of code that was run before:

stat.Text = "Converting to PNG.";
            _piclist.Enabled = false;

           _piclist.Enabled = true;
               stat.Text =
                  "Conversion comlpete.";

You don't see it, because UI freezes while your method execute and you see only last changes. Consider using threads, great article here: http://msdn.microsoft.com/en-us/magazine/cc164037.aspx

Answer 3

How did you confirm that the code was never executed? Did you set a breakpoint?

As soon as the foreach loop is entered, the _piclist.Enabled and stat.Text values set before the loop are are overwritten by the new values (to true and "Conversion complete". Probably the user interface is never updated in the mean time.