C#

private void listView1_SelectedIndexChanged(object sender, EventArgs e)
       {
           this.label1.Text =   listView1.SelectedItems[0].ToString();
       }

internal static void DemoGrouping()
        {
            string[] files = Directory.GetFiles(@"C:\Documents and Settings\TEMP");

            //Convention: Name method so that it explains what the query is doing
            var fileList = from file in files
                           where file.Length > 1
                           orderby file.Length                       
                           group file by file.Length;


            foreach (var group in fileList)
            {
                //First print the group
               Console.WriteLine(group.Key);
                foreach (string subgroup in group)
                Console.WriteLine("   " + subgroup);
            }


        }