的ObservableCollection <class name> .Distinct（）不工作

Question

我隔壁班：

public class MapsDescModel : NotificationObject, IEqualityComparer<MapsDescModel> 
{ 
    public MapsDescModel(ObservableCollection<MainCategories> mainCategoty) 
    { 
     MainCategories = mainCategoty; 
    } 

    private MainCategories _mainCategorySelectedItem; 
    public MainCategories MainCategorySelectedItem 
    { 
     get { return _mainCategorySelectedItem; } 
     set 
     { 
      if (Equals(value, _mainCategorySelectedItem)) return; 
      _mainCategorySelectedItem = value; 
      RaisePropertyChanged("MainCategorySelectedItem"); 
      RaisePropertyChanged("SubCategories"); 
     } 
    } 

    private SubCategories _subCategorySelectedItem; 
    public SubCategories SubCategorySelectedItem 
    { 
     get { return _subCategorySelectedItem; } 
     set 
     { 
      if (Equals(value, _subCategorySelectedItem)) return; 
      _subCategorySelectedItem = value; 
      RaisePropertyChanged("SubCategorySelectedItem"); 
     } 
    } 

    private ObservableCollection<MainCategories> _mainCategories; 
    public ObservableCollection<MainCategories> MainCategories 
    { 
     get { return _mainCategories; } 
     set 
     { 
      if (Equals(value, _mainCategories)) return; 
      _mainCategories = value; 
      RaisePropertyChanged("MainCategories"); 
     } 
    } 

    public ObservableCollection<SubCategories> SubCategories 
    { 
     get 
     { 
      if (MainCategorySelectedItem != null) 
       return 
        Infrastructure.Helpers.ExtensionMethods.ToObservableCollection(
         MainCategorySelectedItem.SubCategory.AsEnumerable()); 
      else return new ObservableCollection<SubCategories>(); 
     } 
    } 


    public bool Equals(MapsDescModel x, MapsDescModel y) 
    { 
     return 
      x.MainCategorySelectedItem.MainCatID == y.MainCategorySelectedItem.MainCatID && 
      x.SubCategorySelectedItem.SubCatID == y.SubCategorySelectedItem.SubCatID; 
    } 

    public int GetHashCode(MapsDescModel obj) 
    { 
     if (Object.ReferenceEquals(obj, null)) return 0; 

     if (obj.MainCategorySelectedItem == null || obj.SubCategorySelectedItem == null) 
      return 0; 
     else return obj.MainCategorySelectedItem.Category.GetHashCode() + obj.SubCategorySelectedItem.Category.GetHashCode(); 
    } 
} 

，我已經在其他類中的下一個集合：

MapsGrid = new ObservableCollection<MapsDescModel>() 

我試圖用MapGrid.Distinct()方法但它不應該如此。

屬性MainCatID和SubCatID是Integer s。 當我將兩個具有相同屬性值的對象插入集合並使用Distinct方法時，什麼都不會發生。我通過代碼（Console.WriteLine(MapsGrid[0].Equals(MapsGrid[1]));）檢查比較返回的結果，即使屬性相同，它也會返回false。 我的錯誤在哪裏？

---

更新：

我編輯MapsDescModel類：

public class MapsDescModel : NotificationObject, IEqualityComparer<MapsDescModel>, IEquatable<MapsDescModel> 
    { 
     public MapsDescModel(ObservableCollection<MainCategories> mainCategoty) 
     { 
      MainCategories = mainCategoty; 

     } 



     private MainCategories _mainCategorySelectedItem; 
     public MainCategories MainCategorySelectedItem 
     { 
      get { return _mainCategorySelectedItem; } 
      set 
      { 
       if (Equals(value, _mainCategorySelectedItem)) return; 
       _mainCategorySelectedItem = value; 
       RaisePropertyChanged("MainCategorySelectedItem"); 
       RaisePropertyChanged("SubCategories"); 
      } 
     } 

     private SubCategories _subCategorySelectedItem; 
     public SubCategories SubCategorySelectedItem 
     { 
      get { return _subCategorySelectedItem; } 
      set 
      { 
       if (Equals(value, _subCategorySelectedItem)) return; 
       _subCategorySelectedItem = value; 
       RaisePropertyChanged("SubCategorySelectedItem"); 
      } 
     } 


     private ObservableCollection<MainCategories> _mainCategories; 
     public ObservableCollection<MainCategories> MainCategories 
     { 
      get { return _mainCategories; } 
      set 
      { 
       if (Equals(value, _mainCategories)) return; 
       _mainCategories = value; 
       RaisePropertyChanged("MainCategories"); 
      } 
     } 

     public ObservableCollection<SubCategories> SubCategories 
     { 
      get 
      { 
       if (MainCategorySelectedItem != null) 
        return 
         Infrastructure.Helpers.ExtensionMethods.ToObservableCollection(
          MainCategorySelectedItem.SubCategory.AsEnumerable()); 
       else return new ObservableCollection<SubCategories>(); 
      } 
     } 


     public bool Equals(MapsDescModel x, MapsDescModel y) 
     { 
      if (x.MainCategorySelectedItem == null || x.SubCategorySelectedItem == null || 
       y.MainCategorySelectedItem == null || y.SubCategorySelectedItem == null) 
       return false; 

      return 
       x.MainCategorySelectedItem.MainCatID == y.MainCategorySelectedItem.MainCatID && 
       x.SubCategorySelectedItem.SubCatID == y.SubCategorySelectedItem.SubCatID; 
     } 

     public int GetHashCode(MapsDescModel obj) 
     { 
      if (Object.ReferenceEquals(obj, null)) return 0; 

      if (obj.MainCategorySelectedItem == null || obj.SubCategorySelectedItem == null) 
       return 0; 
      else return obj.MainCategorySelectedItem.Category.GetHashCode() + obj.SubCategorySelectedItem.Category.GetHashCode(); 
     } 

     public bool Equals(MapsDescModel other) 
     { 
      return 
      this.Equals(this, other); // use definition from IEqualityComparer<T> 
     } 

     public override bool Equals(object obj) 
     { 
      MapsDescModel other = obj as MapsDescModel; 
      if (other == null) 
       return base.Equals(obj); 
      else 
       return this.Equals(other); 
     } 

     public override int GetHashCode() 
     { 
      MapsDescModel other = this as MapsDescModel; 
      if (other == null) 
       return base.GetHashCode(); 
      else 
       return this.GetHashCode(other); 
     } 

，現在當我執行鮮明方法仍不能正常工作。 我知道我的平等方法工作，因爲行'Console.WriteLine（MapsGrid [0] .Equals（MapsGrid [1]））;'返回true。

任何想法？

Answer 1

你已經實現IEqualityComparer<T>，如果你想在你的類的實例傳遞給Distinct這是很好的：

var distinctList = MapGrid.Distinct(new MapsDescModel()); 

但是清潔方法是實現IEquatable<T>代替，因爲Distinct將使用由默認值，如果不通過一個IEqualityComparer<T>：

public class MapsDescModel : NotificationObject, IEqualityComparer<MapsDescModel>, IEquatable<MapsDescModel> 
{ 
... 
    public bool Equals(MapsDescModel y) 
    { 
     return 
      this.Equals(this,y); // use definition from IEqualityComparer<T> 
    } 
} 

我也建議重寫object.Equals和object.GetHashCode爲了保持一致性，如果您喜歡，可以再次使用IEqualityComparer方法（或者如果您決定不再需要，只需將IEqualityComparer方法轉換爲覆蓋方法），就可以再次利用IEqualityComparer方法。

Answer 2

如果您需要幫助，請回答所提問題。

重寫布爾等於（對象obj）被調用，它返回什麼？
你的回答未能回答那個非常關鍵的問題。

既然你不執行對象我懷疑那些覆蓋不叫

Implementing the Equals Method

你申請的IEqualityComparer一類（MapsDescModel），並將其應用到集合

IEqualityComparer Interface

我認爲你需要做的（或者意味着要做的）是Override GetHashCode和Equals on the class MainCategories
但你不張貼MainCategories
的定義，我覺得plur（S）有趣的 - 是

public ObservableCollection<MainCategories> MainCategories 

集合的集合？
考慮沒有命名屬性的類名稱的清晰