C#集合之可观察的集合

　　　　static void Main()
        {
          var data = new ObservableCollection<string>();
          data.CollectionChanged += Data_CollectionChanged;
          data.Add("One");
          data.Add("Two");
          data.Insert(1, "Three");
          data.Remove("One");

        }

        static void Data_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
        {
          Console.WriteLine("action: {0}", e.Action.ToString());

          if (e.OldItems != null)
          {
            Console.WriteLine("starting index for old item(s): {0}", e.OldStartingIndex);
            Console.WriteLine("old item(s):");
            foreach (var item in e.OldItems)
            {
              Console.WriteLine(item);
            }
          }
          if (e.NewItems != null)
          {
            Console.WriteLine("starting index for new item(s): {0}", e.NewStartingIndex);
            Console.WriteLine("new item(s): ");
            foreach (var item in e.NewItems)
            {
              Console.WriteLine(item);
            }
          }


          Console.WriteLine();

        }