EqualityComparer<T> Classe

Définition

Fournit une classe de base pour les implémentations de l'interface générique IEqualityComparer<T>.Provides a base class for implementations of the IEqualityComparer<T> generic interface.

generic <typename T>
public ref class EqualityComparer abstract : System::Collections::Generic::IEqualityComparer<T>, System::Collections::IEqualityComparer
public abstract class EqualityComparer<T> : System.Collections.Generic.IEqualityComparer<T>, System.Collections.IEqualityComparer
[System.Serializable]
public abstract class EqualityComparer<T> : System.Collections.Generic.IEqualityComparer<T>, System.Collections.IEqualityComparer
type EqualityComparer<'T> = class
    interface IEqualityComparer<'T>
    interface IEqualityComparer
[<System.Serializable>]
type EqualityComparer<'T> = class
    interface IEqualityComparer
    interface IEqualityComparer<'T>
Public MustInherit Class EqualityComparer(Of T)
Implements IEqualityComparer, IEqualityComparer(Of T)

Paramètres de type

T

Type des objets à comparer.The type of objects to compare.

Héritage
EqualityComparer<T>
Attributs
Implémente

Exemples

L’exemple suivant crée une collection dictionnaire d’objets de type Box avec un comparateur d’égalité.The following example creates a dictionary collection of objects of type Box with an equality comparer. Deux zones sont considérées comme égales si leurs dimensions sont identiques.Two boxes are considered equal if their dimensions are the same. Il ajoute ensuite les zones à la collection.It then adds the boxes to the collection.

Le dictionnaire est recréé avec un comparateur d’égalité qui définit l’égalité d’une manière différente : deux zones sont considérées comme égales si leurs volumes sont identiques.The dictionary is recreated with an equality comparer that defines equality in a different way: Two boxes are considered equal if their volumes are the same.

using System;
using System.Collections.Generic;

class Program
{
    static Dictionary<Box, String> boxes;

    static void Main()
    {
        BoxSameDimensions boxDim = new BoxSameDimensions();
        boxes = new Dictionary<Box, string>(boxDim);

        Console.WriteLine("Boxes equality by dimensions:");
        Box redBox = new Box(8, 4, 8);
        Box greenBox = new Box(8, 6, 8);
        Box blueBox = new Box(8, 4, 8);
        Box yellowBox = new Box(8, 8, 8);
        AddBox(redBox, "red");
        AddBox(greenBox, "green");
        AddBox(blueBox, "blue");
        AddBox(yellowBox, "yellow");

        Console.WriteLine();
        Console.WriteLine("Boxes equality by volume:");

        BoxSameVolume boxVolume = new BoxSameVolume();
        boxes = new Dictionary<Box, string>(boxVolume);
        Box pinkBox = new Box(8, 4, 8);
        Box orangeBox = new Box(8, 6, 8);
        Box purpleBox = new Box(4, 8, 8);
        Box brownBox = new Box(8, 8, 4);
        AddBox(pinkBox, "pink");
        AddBox(orangeBox, "orange");
        AddBox(purpleBox, "purple");
        AddBox(brownBox, "brown");
    }

    public static void AddBox(Box bx, string name)
    {
        try
        {
            boxes.Add(bx, name);
            Console.WriteLine("Added {0}, Count = {1}, HashCode = {2}",
                name, boxes.Count.ToString(), bx.GetHashCode());
        }
        catch (ArgumentException)
        {
            Console.WriteLine("A box equal to {0} is already in the collection.", name);
        }
    }
}

public class Box
{
    public Box(int h, int l, int w)
    {
        this.Height = h;
        this.Length = l;
        this.Width = w;
    }
    public int Height { get; set; }
    public int Length { get; set; }
    public int Width { get; set; }
}

class BoxSameDimensions : EqualityComparer<Box>
{
    public override bool Equals(Box b1, Box b2)
    {
        if (b1 == null && b2 == null)
            return true;
        else if (b1 == null || b2 == null)
            return false;

        return (b1.Height == b2.Height &&
                b1.Length == b2.Length &&
                b1.Width == b2.Width);
    }

    public override int GetHashCode(Box bx)
    {
        int hCode = bx.Height ^ bx.Length ^ bx.Width;
        return hCode.GetHashCode();
    }
}

class BoxSameVolume : EqualityComparer<Box>
{
    public override bool Equals(Box b1, Box b2)
    {
        if (b1 == null && b2 == null)
            return true;
        else if (b1 == null || b2 == null)
            return false;

        return (b1.Height * b1.Width * b1.Length ==
                b2.Height * b2.Width * b2.Length);
    }

    public override int GetHashCode(Box bx)
    {
        int hCode = bx.Height * bx.Length * bx.Width;
        return hCode.GetHashCode();
    }
}
/* This example produces an output similar to the following:
 *
      Boxes equality by dimensions:
      Added red, Count = 1, HashCode = 46104728
      Added green, Count = 2, HashCode = 12289376
      A box equal to blue is already in the collection.
      Added yellow, Count = 3, HashCode = 43495525

      Boxes equality by volume:
      Added pink, Count = 1, HashCode = 55915408
      Added orange, Count = 2, HashCode = 33476626
      A box equal to purple is already in the collection.
      A box equal to brown is already in the collection.
 *
*/
'Imports System.Collections
Imports System.Collections.Generic

Module Program
    Dim boxes As Dictionary(Of Box, [String])

    Public Sub Main(ByVal args As String())

        Dim boxDim As New BoxSameDimensions()
        boxes = New Dictionary(Of Box, String)(boxDim)

        Console.WriteLine("Boxes equality by dimensions:")
        Dim redBox As New Box(8, 4, 8)
        Dim greenBox As New Box(8, 6, 8)
        Dim blueBox As New Box(8, 4, 8)
        Dim yellowBox As New Box(8, 8, 8)
        AddBox(redBox, "red")
        AddBox(greenBox, "green")
        AddBox(blueBox, "blue")
        AddBox(yellowBox, "yellow")

        Console.WriteLine()
        Console.WriteLine("Boxes equality by volume:")

        Dim boxVolume As New BoxSameVolume()
        boxes = New Dictionary(Of Box, String)(boxVolume)
        Dim pinkBox As New Box(8, 4, 8)
        Dim orangeBox As New Box(8, 6, 8)
        Dim purpleBox As New Box(4, 8, 8)
        Dim brownBox As New Box(8, 8, 4)
        AddBox(pinkBox, "pink")
        AddBox(orangeBox, "orange")
        AddBox(purpleBox, "purple")
        AddBox(brownBox, "brown")
    End Sub

    Public Sub AddBox(ByVal bx As Box, ByVal name As String)
        Try
            boxes.Add(bx, name)
            Console.WriteLine("Added {0}, Count = {1}, HashCode = {2}", _
                              name, boxes.Count.ToString(), bx.GetHashCode())
        Catch generatedExceptionName As ArgumentException
            Console.WriteLine("A box equal to {0} is already in the collection.", name)
        End Try
    End Sub
End Module

Public Class Box
    Public Sub New(ByVal h As Integer, ByVal l As Integer, ByVal w As Integer)
        Me.Height = h
        Me.Length = l
        Me.Width = w
    End Sub
    
    Private _Height As Integer
    Public Property Height() As Integer
        Get
            Return _Height
        End Get
        Set(ByVal value As Integer)
            _Height = value
        End Set
    End Property

    Private _Length As Integer
    Public Property Length() As Integer
        Get
            Return _Length
        End Get
        Set(ByVal value As Integer)
            _Length = value
        End Set
    End Property

    Private _Width As Integer
    Public Property Width() As Integer
        Get
            Return _Width
        End Get
        Set(ByVal value As Integer)
            _Width = value
        End Set
    End Property
End Class

Class BoxSameDimensions : Inherits EqualityComparer(Of Box)
    Public Overloads Overrides Function Equals(ByVal b1 As Box, _
                                      ByVal b2 As Box) As Boolean
        If b1 Is Nothing AndAlso b2 Is Nothing Then
           Return True
        Else If b1 Is Nothing OrElse b2 Is Nothing Then
           Return False
        End If

        Return (b1.Height = b2.Height AndAlso b1.Length = b2.Length _
                                      AndAlso b1.Width = b2.Width)
    End Function

    Public Overloads Overrides Function GetHashCode(ByVal bx As Box) As Integer
        Dim hCode As Integer = bx.Height Xor bx.Length Xor bx.Width
        Return hCode.GetHashCode()
    End Function
End Class

Class BoxSameVolume : Inherits EqualityComparer(Of Box)
    Public Overloads Overrides Function Equals(ByVal b1 As Box, _
                                          ByVal b2 As Box) As Boolean
        If b1 Is Nothing AndAlso b2 Is Nothing Then
           Return True
        Else If b1 Is Nothing OrElse b2 Is Nothing Then
           Return False
        End If

        Return (b1.Height * b1.Width * b1.Length = _
                b2.Height * b2.Width * b2.Length)
    End Function

    Public Overloads Overrides Function GetHashCode(ByVal bx As Box) As Integer
        Dim hCode As Integer = bx.Height * bx.Length * bx.Width
        Return hCode.GetHashCode()
    End Function
End Class
' This example produces an output similar to the following:
' * 
'    Boxes equality by dimensions:
'    Added red, Count = 1, HashCode = 46104728
'    Added green, Count = 2, HashCode = 12289376
'    A box equal to blue is already in the collection.
'    Added yellow, Count = 3, HashCode = 43495525
'
'    Boxes equality by volume:
'    Added pink, Count = 1, HashCode = 55915408
'    Added orange, Count = 2, HashCode = 33476626
'    A box equal to purple is already in the collection.
'    A box equal to brown is already in the collection.
' * 
'

Remarques

Dérivez de cette classe pour fournir une implémentation personnalisée de l' IEqualityComparer<T> interface générique pour une utilisation avec des classes de collection telles que la Dictionary<TKey,TValue> classe générique, ou avec des méthodes telles que List<T>.Sort .Derive from this class to provide a custom implementation of the IEqualityComparer<T> generic interface for use with collection classes such as the Dictionary<TKey,TValue> generic class, or with methods such as List<T>.Sort.

La Default propriété vérifie si le type T implémente l' System.IEquatable<T> interface générique et, si tel est le cas, retourne un objet EqualityComparer<T> qui appelle l’implémentation de la IEquatable<T>.Equals méthode.The Default property checks whether type T implements the System.IEquatable<T> generic interface and, if so, returns an EqualityComparer<T> that invokes the implementation of the IEquatable<T>.Equals method. Sinon, elle retourne un EqualityComparer<T> , comme indiqué par T .Otherwise, it returns an EqualityComparer<T>, as provided by T.

Nous vous recommandons de dériver de la EqualityComparer<T> classe au lieu d’implémenter l' IEqualityComparer<T> interface, car la EqualityComparer<T> classe teste l’égalité à l’aide IEquatable<T>.Equals de la méthode au lieu de la Object.Equals méthode.We recommend that you derive from the EqualityComparer<T> class instead of implementing the IEqualityComparer<T> interface, because the EqualityComparer<T> class tests for equality using the IEquatable<T>.Equals method instead of the Object.Equals method. Cela est cohérent avec les Contains méthodes,, IndexOf LastIndexOf et Remove de la Dictionary<TKey,TValue> classe et d’autres collections génériques.This is consistent with the Contains, IndexOf, LastIndexOf, and Remove methods of the Dictionary<TKey,TValue> class and other generic collections.

Constructeurs

EqualityComparer<T>()

Initialise une nouvelle instance de la classe EqualityComparer<T>.Initializes a new instance of the EqualityComparer<T> class.

Propriétés

Default

Retourne un comparateur d’égalité par défaut pour le type spécifié par l’argument générique.Returns a default equality comparer for the type specified by the generic argument.

Méthodes

Equals(Object)

Détermine si l'objet spécifié est égal à l'objet actuel.Determines whether the specified object is equal to the current object.

(Hérité de Object)
Equals(T, T)

En cas de substitution dans une classe dérivée, détermine si deux objets de type T sont égaux.When overridden in a derived class, determines whether two objects of type T are equal.

GetHashCode()

Fait office de fonction de hachage par défaut.Serves as the default hash function.

(Hérité de Object)
GetHashCode(T)

En cas de substitution dans une classe dérivée, sert de fonction de hachage pour l'objet spécifié pour le hachage d'algorithmes et des structures de données, telles qu'une table de hachage.When overridden in a derived class, serves as a hash function for the specified object for hashing algorithms and data structures, such as a hash table.

GetType()

Obtient le Type de l'instance actuelle.Gets the Type of the current instance.

(Hérité de Object)
MemberwiseClone()

Crée une copie superficielle du Object actuel.Creates a shallow copy of the current Object.

(Hérité de Object)
ToString()

Retourne une chaîne qui représente l'objet actuel.Returns a string that represents the current object.

(Hérité de Object)

Implémentations d’interfaces explicites

IEqualityComparer.Equals(Object, Object)

Détermine si les objets spécifiés sont égaux.Determines whether the specified objects are equal.

IEqualityComparer.GetHashCode(Object)

Retourne un code de hachage pour l'objet spécifié.Returns a hash code for the specified object.

S’applique à

Voir aussi