c# - 如何对 KeyedCollection 进行排序?

Question

基本上我有一个KeyedCollection<string, CustomNode>，我希望能够通过键（或者最好使用自定义比较器）对集合进行排序。

如果这是不可能的，有人可以推荐另一个类，其中键嵌入在我可以排序的值中吗？

Answer 1

Upon further information (see comments on answer above), a requirement is to keep the "set" sorted by a element's property after the property is edited.

In this case, you might take a look at BindableLinq (there are other similar frameworks too) and use the OrderBy statement implemented in there.

KeyedCollection<string, CustomNode> collection = /* from whereever */
collection.Items.AsBindable().OrderBy(c => c.PropertyOnCustomNode);

As long as your edited property raises a PropertyChanged event then it'll apply the re-ordering immediately. If you wish to change your collection, then ensure that the source collection implements INotifyCollectionChanged.

Answer 2

在尝试解决类似问题时出现了这个问题。如果它仍然相关，我可以使用此处的示例实现排序：

http://social.msdn.microsoft.com/forums/en-US/netfxbcl/thread/56adc0f9-aa1b-4acf-8546-082bb01058f2/

基本上涉及对集合的基础列表进行排序。对我来说就像一个魅力。

干杯!

Answer 3

KeyCollection<T>继承自Collection<T>which implementsIEnumerable所以你应该能够使用IEnumerable.OrderBy(). IEnumerable.OrderBy()还具有允许您提供自定义比较器的重载。

Answer 4

这是基于 Dan 在回答中提供的链接：http: //social.msdn.microsoft.com/forums/en-US/netfxbcl/thread/56adc0f9-aa1b-4acf-8546-082bb01058f2/

   public class RequestTemplate : IComparable<RequestTemplate>
   {
      // This is the primary key for the object
      private Guid _guidNumber;

      // This is what a collection of these objects should be sorted by
      private string _buttonCaption = "";


      public Guid GuidNumber
      {
         get { return _guidNumber; }
         set { _guidNumber = value; }  // Setter only provided for deserialization usage
      }

      public string ButtonCaption
      {
         get { return _buttonCaption; }
         set { _buttonCaption = value; }
      }


      /// <summary>
      /// Method needed to allow sorting a collection of these objects.
      /// </summary>
      public int CompareTo(RequestTemplate other)
      {
         return string.Compare(this.ButtonCaption, other.ButtonCaption, 
                               StringComparison.CurrentCultureIgnoreCase);
      }
   }


   public class RequestTemplateKeyedCollection : KeyedCollection<Guid, RequestTemplate>
   {
      /// <summary>
      /// Sort the collection by sorting the underlying collection, accessed by casting the Items 
      /// property from IList to List.
      /// </summary>
      public void Sort()
      {
         List<RequestTemplate> castList = base.Items as List<RequestTemplate>;
         if (castList != null)
            castList.Sort();  // Uses default Sort() for collection items (RequestTemplate)
      }


      /// <summary>
      /// Method needed by KeyedCollection.
      /// </summary>
      protected override Guid GetKeyForItem(RequestTemplate requestTemplate)
      {
         return requestTemplate.GuidNumber;
      }
   }

尚未对其进行广泛测试，但似乎可以正常工作。

Answer 5

您可能会查看SortedDictionary集合......但这会增加项目检索 O(log N) 的费用，而不是使用 O(1) 检索的 KeyedCollection。