Tuple<T1,T2>.IStructuralEquatable.Equals(Object, IEqualityComparer) 方法

定义

返回一个值,该值根据指定的比较方法指示当前的 Tuple<T1,T2> 对象是否与指定对象相等。Returns a value that indicates whether the current Tuple<T1,T2> object is equal to a specified object based on a specified comparison method.

 virtual bool System.Collections.IStructuralEquatable.Equals(System::Object ^ other, System::Collections::IEqualityComparer ^ comparer) = System::Collections::IStructuralEquatable::Equals;
bool IStructuralEquatable.Equals (object other, System.Collections.IEqualityComparer comparer);
Function Equals (other As Object, comparer As IEqualityComparer) As Boolean Implements IStructuralEquatable.Equals

参数

other
Object

与该实例进行比较的对象。The object to compare with this instance.

comparer
IEqualityComparer

一个对象,该对象定义用于评估两个对象是否相等的方法。An object that defines the method to use to evaluate whether the two objects are equal.

返回

如果当前实例等于指定对象,则为 true;否则为 falsetrue if the current instance is equal to the specified object; otherwise, false.

实现

示例

下面的示例定义一个Item2Comparer IEqualityComparer实现接口的类, 并Tuple<T1,T2>更改计算对象的相等性的方式。The following example defines an Item2Comparer class that implements the IEqualityComparer interface and changes the way in which Tuple<T1,T2> objects are evaluated for equality. true当向Tuple<T1,T2> IStructuralEquatable.Equals传递两个对象的Item2属性值时, 此方法始终返回, 并调用方法来计算其属性值。 Item1The method always returns true when it is passed the Item1 property values of two Tuple<T1,T2> objects, and it calls the IStructuralEquatable.Equals method to evaluate their Item2 property values. 因此, 方法仅基于Item2属性的值测试相等性。As a result, the method tests for equality based only on the value of the Item2 property. 输出说明了一组Tuple<T1,T2>对象的结果, 这些对象记录了运行程序的名称和运行的距离。The output illustrates the result for a data set of Tuple<T1,T2> objects that record the names of runners and the distances that they ran.

using System;
using System.Collections;

public class Item2Comparer<T1, T2> : IEqualityComparer
{
   new public bool Equals(object x, object y)
   {
      // Return true for all values of Item1.
      if (x is T1)
      //if (typeof(x) is string) 
         return true;
      else
         return x.Equals(y);
   }
   
   public int GetHashCode(object obj)
   {
      if (obj is T1)
         return ((T1) obj).GetHashCode();
      else
         return ((T2) obj).GetHashCode();
   }                
}

public class Example
{
   public static void Main()
   {
      Tuple<string, double>[] distancesWalked = {
                        Tuple.Create("Jan", Double.NaN), 
                        Tuple.Create("Joe", Double.NaN), 
                        Tuple.Create("Adam", 1.36), 
                        Tuple.Create("Selena", 2.01),
                        Tuple.Create("Jake", 1.36) };
      for (int ctr = 0; ctr < distancesWalked.Length; ctr++)
      {
         Tuple<string, double> distanceWalked = distancesWalked[ctr];
         for (int ctr2 = ctr + 1; ctr2 < distancesWalked.Length; ctr2++)
         {
            Console.WriteLine("{0} = {1}: {2}", distanceWalked, 
                              distancesWalked[ctr2], 
                              ((IStructuralEquatable)distanceWalked).Equals(distancesWalked[ctr2], 
                                                    new Item2Comparer<string, double>()));
         }
         Console.WriteLine();
      }   
   }
}
// The example displays the following output:
//       (Jan, NaN) = (Joe, NaN): True
//       (Jan, NaN) = (Adam, 1.36): False
//       (Jan, NaN) = (Selena, 2.01): False
//       (Jan, NaN) = (Jake, 1.36): False
//       
//       (Joe, NaN) = (Adam, 1.36): False
//       (Joe, NaN) = (Selena, 2.01): False
//       (Joe, NaN) = (Jake, 1.36): False
//       
//       (Adam, 1.36) = (Selena, 2.01): False
//       (Adam, 1.36) = (Jake, 1.36): True
//       
//       (Selena, 2.01) = (Jake, 1.36): False
Imports System.Collections

Public Class Item2Comparer(Of T1, T2) : Implements IEqualityComparer
   
   Public Overloads Function Equals(x As Object, y As Object) As Boolean _
                   Implements IEqualityComparer.Equals
      ' Return true for all values of Item1.
      If TypeOf x Is T1 Then
         Return True
      Else
         Return x.Equals(y)
      End If
   End Function
   
   Public Overloads Function GetHashCode(obj As Object) As Integer _
                    Implements IEqualityComparer.GetHashCode
      If TypeOf obj Is T1 Then
         Return CType(obj, T1).GetHashCode()
      Else
         Return CType(obj, T2).GetHashCode()
      End If   
   End Function                
End Class

Module Example
   Public Sub Main()
      Dim distancesWalked() = {
                        Tuple.Create("Jan", Double.NaN), 
                        Tuple.Create("Joe", Double.NaN), 
                        Tuple.Create("Adam", 1.36), 
                        Tuple.Create("Selena", 2.01),
                        Tuple.Create("Jake", 1.36) }
      For ctr As Integer = 0 To distancesWalked.Length - 1
         Dim distanceWalked As Tuple(Of String, Double) = distancesWalked(ctr)
         For ctr2 As Integer = ctr + 1 To distancesWalked.Length - 1
            Console.WriteLine("{0} = {1}: {2}", distanceWalked, 
                              distancesWalked(ctr2), 
                              DirectCast(distanceWalked, IStructuralEquatable).Equals(distancesWalked(ctr2), 
                                                    new Item2Comparer(Of String, Double)))
         Next
         Console.WriteLine()
      Next                     
   End Sub
End Module
' The example displays the following output:
'       (Jan, NaN) = (Joe, NaN): True
'       (Jan, NaN) = (Adam, 1.36): False
'       (Jan, NaN) = (Selena, 2.01): False
'       (Jan, NaN) = (Jake, 1.36): False
'       
'       (Joe, NaN) = (Adam, 1.36): False
'       (Joe, NaN) = (Selena, 2.01): False
'       (Joe, NaN) = (Jake, 1.36): False
'       
'       (Adam, 1.36) = (Selena, 2.01): False
'       (Adam, 1.36) = (Jake, 1.36): True
'       
'       (Selena, 2.01) = (Jake, 1.36): False

注解

此成员是显式接口成员的实现。This member is an explicit interface member implementation. 它只能在 Tuple<T1,T2> 实例被强制转换为 IStructuralEquatable 接口时使用。It can be used only when the Tuple<T1,T2> instance is cast to an IStructuralEquatable interface.

C# Tuple<T1,T2>仅当other不为null时, 才会调用实现,并且如果它可以成功地强制转换(在中)或转换(在VisualBasic)到其组件类型与当前实例相同的对象。IStructuralEquatable.EqualsThe IStructuralEquatable.Equals implementation is called only if other is not null, and if it can be successfully cast (in C#) or converted (in Visual Basic) to a Tuple<T1,T2> object whose components are of the same types as the current instance. 方法首先Tuple<T1,T2> IEqualityComparer.Equals传递要与实现进行比较的对象的值。Item1 IStructuralEquatable.EqualsThe IStructuralEquatable.Equals method first passes the Item1 values of the Tuple<T1,T2> objects to be compared to the IEqualityComparer.Equals implementation. 如果此方法调用返回true, 将再次调用方法并Item2传递两个Tuple<T1,T2>对象的值。If this method call returns true, the method is called again and passed the Item2 values of the two Tuple<T1,T2> objects.

适用于

另请参阅