private void Sell_Load(object sender, EventArgs e) { Mainmenu = Application.OpenForms["MainMenu"]; foreach (Product item in ((MainMenu)Mainmenu).GetProduct()) { ListViewItem li = new ListViewItem(); li.Text = item.ProductName; li.SubItems.Add(item.UnitPrice.ToString()); lstSell.Items.Add(li); } txtPrice.Text = orepo.CalculatePrice(((MainMenu)Mainmenu).GetProduct()).ToString(); }