C# 可观察集合

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

     }