Question

I am encountering an odd issue whereby I can move items from one list box to another, but cannot move any items back to the original list box. Here is my code:

private void MoveListBoxItems(ListBox from, ListBox to)
{
    for(int i = 0; i < first_listbox.Items.Count; i++)
    {
        if (first_listbox.Items[i].Selected)
        {
            to.Items.Add(from.SelectedItem);
            from.Items.Remove(from.SelectedItem);
        }   
    }
    from.SelectedIndex = -1;
    to.SelectedIndex = -1;
}

protected void Button2_Click(object sender, EventArgs e)
{
    MoveListBoxItems(first_listbox, second_listbox);
}

protected void Button1_Click(object sender, EventArgs e)
{
    MoveListBoxItems(second_listbox, first_listbox); 
}

The button2 event works fine, however the button1 event does not. The list boxes are not data bound and I have manually added items to them.

Maybe there is something very obvious that I am missing here?

Thanks for your help in advance.

Answer 1

Change it to this:

private void MoveListBoxItems(ListBox from, ListBox to)
{
    for(int i = 0; i < from.Items.Count; i++)
    {
        if (from.Items[i].Selected)
        {
            to.Items.Add(from.SelectedItem);
            from.Items.Remove(from.SelectedItem);

            // should probably be this:
            to.Items.Add(from.Items[i]);
            from.Items.Remove(from.Items[i]);
        }   
    }
    from.SelectedIndex = -1;
    to.SelectedIndex = -1;
}

Your original method was using first_listbox in these two places, instead of from. Also, I imagine your code does not work if more than one item is selected.