public void date_date()
        {
            items.Clear();
            // format random values. You can implement a dedicated class to provide real values
            for (int i = 0; i < 31; i++)
            {
                System.Random r = new System.Random();

                int a = r.Next(10);
                if (a > 6)
                {
                    items.Add(i.ToString());
                }
                else
                {
                    Console.WriteLine("Ok");
                }
            }

            adapter.setItems(items);
            adapter.NotifyDataSetChanged();
        }