C＃List.Contains在它應該返回true時

Question

因此，我創建了一個Noughts和Crosses應用程序（我的美國朋友的Tic tac腳趾）只是爲了練習一點而我偶然發現了一個問題。

我在List<PlayerPositons>有3個項目，我試圖尋找一個特定的位置。然而，當我使用LINQ方法Contains它不會返回真正的時候，我正在尋找一個我知道肯定的位置。

下面是代碼：

private void CheckIfWinner(object sender, PlayerClickedOnBoardEventArgs e) { 
    if (e.CurrentPositions != null) { 
     var potentialWinnersPositions = e.CurrentPositions.GroupBy(r => r.Player).Where(r => r.Count() >= 3); 

     foreach (var item in potentialWinnersPositions) { 
      var verticalGrouping = item.Where(r => r.Player == item.Key).GroupBy(r => r.VerticalPosition); 
      //If there are three vertically then there must be a winner 
      foreach (var vert in verticalGrouping) { 
       if (vert.Select(r => r.VerticalPosition).Count() == 3) { 
        _view.WinnerMessage = $"Congratulations player {item.Key}. You won!"; 
        return; 
       } 
      } 

      var horizontalGrouping = item.Where(r => r.Player == item.Key).GroupBy(r => r.HorizontalPositon); 
      //If there are three hoirzontally then there must be a winner 
      foreach (var horiz in horizontalGrouping) { 
       if (horiz.Select(r => r.HorizontalPositon).Count() == 3) { 
        _view.WinnerMessage = $"Congratulations player {item.Key}. You won!"; 
        return; 
       } 
      } 

      //If item contains the center button then there is a possibility of a winner 
      //Happens here 
      if (item.Select(r => r).Contains(new Models.PlayerPosition(item.Key, Models.Position._verticalPosition.Middle, Models.Position._horizontalPosition.Middle))) { 
       if (item.Where(r => r.VerticalPosition == Models.Position._verticalPosition.Top) != null && item.Where(r => r.VerticalPosition == Models.Position._verticalPosition.Bottom) != null) { 
        _view.WinnerMessage = $"Congratulations player {item.Key}. You won!"; 
        return; 
       } 
      } 
     } 
    } 
} 

所以我試圖尋找在廣場和項目中心塊包含下列項目：

PositionCollection positions = new PositionCollection() { 
    new PlayerPosition('x', Position._verticalPosition.Top, Position._horizontalPosition.Left), 
    new PlayerPosition('o', Position._verticalPosition.Middle, Position._horizontalPosition.Left), 
    new PlayerPosition('x', Position._verticalPosition.Middle, Position._horizontalPosition.Middle), 
    new PlayerPosition('o', Position._verticalPosition.Middle, Position._horizontalPosition.Right), 
    new PlayerPosition('x', Position._verticalPosition.Bottom, Position._horizontalPosition.Right), 
}; 

爲什麼Contains返回false？

編輯 - PlayerPosition類：

public class PlayerPosition : IEquatable<PlayerPosition>{ 
    public enum _verticalPosition { Top, Middle, Bottom }; 
    public enum _horizontalPosition { Left, Middle, Right }; 
    public PlayerPosition(char player, _verticalPosition vert, _horizontalPosition horiz) { 
     if (player != 'x' && player != 'o') { 
      throw new ArgumentException("Player must be either x or o."); 
     } 
     Player = player; 
     VerticalPosition = vert; 
     HorizontalPositon = horiz; 
    } 

    public char Player { get; set; } 
    public _verticalPosition VerticalPosition { get; set; } 
    public _horizontalPosition HorizontalPositon { get; set; } 

    public override bool Equals(object obj) { 
     PlayerPosition pos = (PlayerPosition)obj; 
     if (obj == null) { 
      return false; 
     } 
     else if (pos.HorizontalPositon == HorizontalPositon && pos.VerticalPosition == VerticalPosition 
       && pos.Player == Player) { 
      return true; 
     } 

     return false; 
    } 

    public override int GetHashCode() { 
     return base.GetHashCode(); 
    } 

    public bool Equals(PlayerPosition other) { 
     if (other == null) { 
      return false; 
     } 
     else if (other.HorizontalPositon == HorizontalPositon && other.VerticalPosition == VerticalPosition 
       && other.Player == Player) { 
      return true; 
     } 

     return false; 
    } 

    public static bool operator ==(PlayerPosition a, PlayerPosition b) { 
     return Equals(a, b); 
    } 

    public static bool operator !=(PlayerPosition a, PlayerPosition b) { 
     return !Equals(a, b); 
    } 
} 

Answer 1

所以從我個人理解，LINQ Contains使用默認的對象Equals法計算的值是否相等。

在我的例子中，他們根據Equals算子不相等，所以我已經超越了Equals和GetHashCode方法。 Contains方法現在使用這些來計算它們是否相等。

呼籲Rufo爵士幫助我。

public class PlayerPosition { 
     public enum _verticalPosition { Top, Middle, Bottom }; 
     public enum _horizontalPosition { Left, Middle, Right }; 

     public PlayerPosition(char player, _verticalPosition vert, _horizontalPosition horiz) { 
      if (player != 'x' && player != 'o') { 
       throw new ArgumentException("Player must be either x or o."); 
      } 
      Player = player; 
      VerticalPosition = vert; 
      HorizontalPositon = horiz; 
     } 

     public char Player { get; set; } 
     public _verticalPosition VerticalPosition { get; set; } 
     public _horizontalPosition HorizontalPositon { get; set; } 

     public override bool Equals(object obj) { 
      PlayerPosition pos = (PlayerPosition)obj; 
      if (obj == null) { 
       return false; 
      } 
      else if (pos.HorizontalPositon == HorizontalPositon && pos.VerticalPosition == VerticalPosition 
        && pos.Player == Player) { 
       return true; 
      } 

      return false; 
     } 

     public override int GetHashCode() { 
      return Player.GetHashCode()^HorizontalPositon.GetHashCode()^VerticalPosition.GetHashCode(); 
     } 

     public static bool operator ==(PlayerPosition a, PlayerPosition b) { 
      return Equals(a, b); 
     } 

     public static bool operator !=(PlayerPosition a, PlayerPosition b) { 
      return !Equals(a, b); 

     } 
    } 

Answer 2

包含用於參考的比較檢查.Equals()。也許你需要的是==檢查實際座標。 因此，而不是：

.Contains(new Models.PlayerPosition(item.Key, Models.Position._verticalPosition.Middle, Models.Position._horizontalPosition.Middle)) 

嘗試類似：

.Any(r => r.VerticalPosition == Models.Position._verticalPosition.Middle && r.HorizontalPosition == Models.Position._horizontalPosition.Middle))