private void Button_Click(object sender, RoutedEventArgs e) { SortsAndFilters sf = new SortsAndFilters(); List <Song> songList = sf.RetrieveNotOwnedSongs(1); List <string> songNames = new List <string>(); foreach (Song s in songList) { songNames.Add(s.SongName); } MessageBox.Show(string.Join("---", songNames)); }