Question

I am making a C# program which is runnning 2 threads. The main UI thread, and a seperate network thread i make myself.

I have figured out, that if i need to change something in the UI from the network thread, i will need to call a deligate method, which works just fine:

// Declared as a global variable
public delegate void ListBoxFirst();

//Then call this from the network thread
listBox1.BeginInvoke(new ListBoxFirst(InitListBox));

//Which points to this
public void InitListBox() {
     listBox1.SelectedIndex = 0;
}

Now i need to be able to read a UI value (a listbox.selectedindex) from the network thread, but it shows the error “cannot implicitly convert type ‘system.iasyncresult’ to ‘int'” if i try it the same way (of course with “int” instead of “void”, and a “int a = ” before the listbox1.begininvoke). I have googled a lot but im pretty new to C# so i get really lost.

Any help would be much appriciated

Answer 1

I figured it out:

public int ReadListBoxIndex()
    {
        int count = 0;
        listBox1.Invoke(new MethodInvoker(delegate
        {
            count = listBox1.SelectedIndex;
        }));
        return count;
    }

Called with a regular

int count = ReadListBoxIndex();