EqualityComparer<T> Klasse
Definition
Stellt eine Basisklasse für Implementierungen der generischen IEqualityComparer<T>-Schnittstelle bereit.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
[System.Serializable]
public abstract class EqualityComparer<T> : System.Collections.Generic.IEqualityComparer<T>, System.Collections.IEqualityComparer
type EqualityComparer<'T> = class
interface IEqualityComparer
interface IEqualityComparer<'T>
Public MustInherit Class EqualityComparer(Of T)
Implements IEqualityComparer, IEqualityComparer(Of T)
Typparameter
- T
Der Typ der zu vergleichenden Objekte.The type of objects to compare.
- Vererbung
-
EqualityComparer<T>
- Attribute
- Implementiert
Beispiele
Im folgenden Beispiel wird eine Wörterbuch Auflistung von Objekten vom Box
Typ mit einem Gleichheits Vergleich erstellt.The following example creates a dictionary collection of objects of type Box
with an equality comparer. Zwei Felder werden als gleich betrachtet, wenn ihre Dimensionen identisch sind.Two boxes are considered equal if their dimensions are the same. Anschließend werden die Felder zur Auflistung hinzugefügt.It then adds the boxes to the collection.
Das Wörterbuch wird mit einem Gleichheits Vergleich neu erstellt, der Gleichheit auf eine andere Weise definiert: Zwei Felder werden als gleich betrachtet, wenn die Volumes identisch sind.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 the following output:
*
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 the following output:
' *
' 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.
' *
'
Hinweise
Leiten Sie von dieser Klasse ab, um eine benutzerdefinierte IEqualityComparer<T> Implementierung der generischen-Schnittstelle zur Verwendung mit Dictionary<TKey,TValue> Auflistungs Klassen wie der generischen List<T>.Sort-Klasse oder mit Methoden wie bereitzustellen.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.
Die Default -Eigenschaft überprüft, T
ob der System.IEquatable<T> Typ die generische-Schnittstelle implementiert, und EqualityComparer<T> IEquatable<T>.Equals gibt in diesem Fall eine zurück, die die Implementierung der-Methode aufruft.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. Andernfalls wird ein EqualityComparer<T>zurückgegeben, wie von T
bereitgestellt.Otherwise, it returns an EqualityComparer<T>, as provided by T
.
Es wird empfohlen, dass Sie von EqualityComparer<T> der-Klasse ableiten, IEqualityComparer<T> anstatt die-Schnitt EqualityComparer<T> Stelle zu implementieren, da die IEquatable<T>.Equals -Klasse mithilfe der Object.Equals -Methode anstelle der-Methode auf Gleichheit prüft.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. Dies entspricht Contains
den Methoden, LastIndexOf
IndexOf
, und Remove
der Dictionary<TKey,TValue> -Klasse und anderen generischen Auflistungen.This is consistent with the Contains
, IndexOf
, LastIndexOf
, and Remove
methods of the Dictionary<TKey,TValue> class and other generic collections.
Konstruktoren
EqualityComparer<T>() |
Initialisiert eine neue Instanz der EqualityComparer<T>-Klasse.Initializes a new instance of the EqualityComparer<T> class. |
Eigenschaften
Default |
Gibt für den vom generischen Argument angegebenen Typ einen Standardgleichheitsvergleich zurück.Returns a default equality comparer for the type specified by the generic argument. |
Methoden
Equals(Object) |
Ermittelt, ob das angegebene Objekt und das aktuelle Objekt gleich sind.Determines whether the specified object is equal to the current object. (Geerbt von Object) |
Equals(T, T) |
Ermittelt beim Überschreiben in einer abgeleiteten Klasse, ob zwei Objekte vom Typ |
GetHashCode() |
Dient als die Standard-HashfunktionServes as the default hash function. (Geerbt von Object) |
GetHashCode(T) |
Dient beim Überschreiben in einer abgeleiteten Klasse für das angegebene Objekt als Hashfunktion für Hashalgorithmen und Datenstrukturen wie Hashtabellen.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() |
Ruft den Type der aktuellen Instanz ab.Gets the Type of the current instance. (Geerbt von Object) |
MemberwiseClone() |
Erstellt eine flache Kopie des aktuellen Object.Creates a shallow copy of the current Object. (Geerbt von Object) |
ToString() |
Gibt eine Zeichenfolge zurück, die das aktuelle Objekt darstellt.Returns a string that represents the current object. (Geerbt von Object) |
Explizite Schnittstellenimplementierungen
IEqualityComparer.Equals(Object, Object) |
Bestimmt, ob die angegebenen Objekte gleich sind.Determines whether the specified objects are equal. |
IEqualityComparer.GetHashCode(Object) |
Gibt einen Hashcode für das angegebene Objekt zurück.Returns a hash code for the specified object. |