Comparer<T> Klasse

Definition

generic <typename T>
public ref class Comparer abstract : System::Collections::Generic::IComparer<T>, System::Collections::IComparer

public abstract class Comparer<T> : System.Collections.Generic.IComparer<T>, System.Collections.IComparer

[System.Serializable]
public abstract class Comparer<T> : System.Collections.Generic.IComparer<T>, System.Collections.IComparer

type Comparer<'T> = class
    interface IComparer<'T>
    interface IComparer

[<System.Serializable>]
type Comparer<'T> = class
    interface IComparer
    interface IComparer<'T>

Public MustInherit Class Comparer(Of T)
Implements IComparer, IComparer(Of T)

Typparameter

Vererbung

Object

Comparer<T>

Attribute

SerializableAttribute

Implementiert

IComparer<T> IComparer

Beispiele

Im folgenden Beispiel wird eine Klasse , BoxLengthFirstvon der Comparer<T> Klasse abgeleitet. Dieser Vergleich vergleicht zwei Objekte vom Typ Box. Sie sortiert sie zuerst nach Länge, dann nach Höhe und dann nach Breite. Die Box Klasse implementiert die IComparable<T> Schnittstelle, um den Standardvergleich zwischen zwei Box Objekten zu steuern. Diese Standardimplementierung sortiert zuerst nach Höhe, dann nach Länge und dann nach Breite. Das Beispiel zeigt die Unterschiede zwischen den beiden Vergleichen, indem zuerst eine Liste von Box Objekten mithilfe des BoxLengthFirst Vergleichs und dann mithilfe des Standardvergleichs sortiert wird.

using System;
using System.Collections;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        List<Box> Boxes = new List<Box>();
        Boxes.Add(new Box(4, 20, 14));
        Boxes.Add(new Box(12, 12, 12));
        Boxes.Add(new Box(8, 20, 10));
        Boxes.Add(new Box(6, 10, 2));
        Boxes.Add(new Box(2, 8, 4));
        Boxes.Add(new Box(2, 6, 8));
        Boxes.Add(new Box(4, 12, 20));
        Boxes.Add(new Box(18, 10, 4));
        Boxes.Add(new Box(24, 4, 18));
        Boxes.Add(new Box(10, 4, 16));
        Boxes.Add(new Box(10, 2, 10));
        Boxes.Add(new Box(6, 18, 2));
        Boxes.Add(new Box(8, 12, 4));
        Boxes.Add(new Box(12, 10, 8));
        Boxes.Add(new Box(14, 6, 6));
        Boxes.Add(new Box(16, 6, 16));
        Boxes.Add(new Box(2, 8, 12));
        Boxes.Add(new Box(4, 24, 8));
        Boxes.Add(new Box(8, 6, 20));
        Boxes.Add(new Box(18, 18, 12));

        // Sort by an Comparer<T> implementation that sorts
        // first by the length.
        Boxes.Sort(new BoxLengthFirst());

        Console.WriteLine("H - L - W");
        Console.WriteLine("==========");
        foreach (Box bx in Boxes)
        {
            Console.WriteLine("{0}\t{1}\t{2}",
                bx.Height.ToString(), bx.Length.ToString(),
                bx.Width.ToString());
        }

        Console.WriteLine();
        Console.WriteLine("H - L - W");
        Console.WriteLine("==========");

        // Get the default comparer that
        // sorts first by the height.
        Comparer<Box> defComp = Comparer<Box>.Default;

        // Calling Boxes.Sort() with no parameter
        // is the same as calling Boxs.Sort(defComp)
        // because they are both using the default comparer.
        Boxes.Sort();

        foreach (Box bx in Boxes)
        {
            Console.WriteLine("{0}\t{1}\t{2}",
                bx.Height.ToString(), bx.Length.ToString(),
                bx.Width.ToString());
        }


        // This explicit interface implementation
        // compares first by the length.
        // Returns -1 because the length of BoxA
        // is less than the length of BoxB.
        BoxLengthFirst LengthFirst = new BoxLengthFirst();

        Comparer<Box> bc = (Comparer<Box>) LengthFirst;

        Box BoxA = new Box(2, 6, 8);
        Box BoxB = new Box(10, 12, 14);
        int x = LengthFirst.Compare(BoxA, BoxB);
        Console.WriteLine();
        Console.WriteLine(x.ToString());
    }
}

public class BoxLengthFirst : Comparer<Box>
{
    // Compares by Length, Height, and Width.
    public override int Compare(Box x, Box y)
    {
        if (x.Length.CompareTo(y.Length) != 0)
        {
            return x.Length.CompareTo(y.Length);
        }
        else if (x.Height.CompareTo(y.Height) != 0)
        {
            return x.Height.CompareTo(y.Height);
        }
        else if (x.Width.CompareTo(y.Width) != 0)
        {
            return x.Width.CompareTo(y.Width);
        }
        else
        {
            return 0;
        }
    }
}

// This class is not demonstrated in the Main method
// and is provided only to show how to implement
// the interface. It is recommended to derive
// from Comparer<T> instead of implementing IComparer<T>.
public class BoxComp : IComparer<Box>
{
    // Compares by Height, Length, and Width.
    public int Compare(Box x, Box y)
    {
        if (x.Height.CompareTo(y.Height) != 0)
        {
            return x.Height.CompareTo(y.Height);
        }
        else if (x.Length.CompareTo(y.Length) != 0)
        {
            return x.Length.CompareTo(y.Length);
        }
        else if (x.Width.CompareTo(y.Width) != 0)
        {
            return x.Width.CompareTo(y.Width);
        }
        else
        {
            return 0;
        }
    }
}

public class Box : IComparable<Box>
{

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

    public int CompareTo(Box other)
    {
        // Compares Height, Length, and Width.
        if (this.Height.CompareTo(other.Height) != 0)
        {
            return this.Height.CompareTo(other.Height);
        }
        else if (this.Length.CompareTo(other.Length) != 0)
        {
            return this.Length.CompareTo(other.Length);
        }
        else if (this.Width.CompareTo(other.Width) != 0)
        {
            return this.Width.CompareTo(other.Width);
        }
        else
        {
            return 0;
        }
    }
}

open System
open System.Collections.Generic

type Box(h, l, w) =
    member val Height: int = h with get
    member val Length: int = l with get
    member val Width: int = w with get

    interface IComparable<Box> with
        member this.CompareTo(other) =
            // Compares Height, Length, and Width.
            if this.Height.CompareTo other.Height <> 0 then
                this.Height.CompareTo other.Height
            elif this.Length.CompareTo other.Length <> 0 then
                this.Length.CompareTo other.Length
            elif this.Width.CompareTo other.Width <> 0 then
                this.Width.CompareTo other.Width
            else
                0

type BoxLengthFirst() =
    inherit Comparer<Box>()

    // Compares by Length, Height, and Width.
    override _.Compare(x: Box, y: Box) =
        if x.Length.CompareTo y.Length <> 0 then
            x.Length.CompareTo y.Length
        elif x.Height.CompareTo y.Height <> 0 then
            x.Height.CompareTo y.Height
        elif x.Width.CompareTo y.Width <> 0 then
            x.Width.CompareTo y.Width
        else
            0

let boxes = ResizeArray<Box>()
boxes.Add(Box(4, 20, 14))
boxes.Add(Box(12, 12, 12))
boxes.Add(Box(8, 20, 10))
boxes.Add(Box(6, 10, 2))
boxes.Add(Box(2, 8, 4))
boxes.Add(Box(2, 6, 8))
boxes.Add(Box(4, 12, 20))
boxes.Add(Box(18, 10, 4))
boxes.Add(Box(24, 4, 18))
boxes.Add(Box(10, 4, 16))
boxes.Add(Box(10, 2, 10))
boxes.Add(Box(6, 18, 2))
boxes.Add(Box(8, 12, 4))
boxes.Add(Box(12, 10, 8))
boxes.Add(Box(14, 6, 6))
boxes.Add(Box(16, 6, 16))
boxes.Add(Box(2, 8, 12))
boxes.Add(Box(4, 24, 8))
boxes.Add(Box(8, 6, 20))
boxes.Add(Box(18, 18, 12))

// Sort by an Comparer<T> implementation that sorts
// first by the length.
boxes.Sort(BoxLengthFirst())

printfn "H - L - W"
printfn "=========="

for bx in boxes do
    printfn $"{bx.Height}\t{bx.Length}\t{bx.Width}"

printfn ""
printfn "H - L - W"
printfn "=========="

// Get the default comparer that
// sorts first by the height.
let defComp = Comparer<Box>.Default

// Calling Boxes.Sort() with no parameter
// is the same as calling boxes.Sort defComp
// because they are both using the default comparer.
boxes.Sort()

for bx in boxes do
    printfn $"{bx.Height}\t{bx.Length}\t{bx.Width}"


// This explicit interface implementation
// compares first by the length.
// Returns -1 because the length of BoxA
// is less than the length of BoxB.
let LengthFirst = BoxLengthFirst()

let bc = LengthFirst :> Comparer<Box>

let BoxA = Box(2, 6, 8)
let BoxB = Box(10, 12, 14)
let x = LengthFirst.Compare(BoxA, BoxB)
printfn $"\n{x}"

// This class is not demonstrated in the Main method
// and is provided only to show how to implement
// the interface. It is recommended to derive
// from Comparer<T> instead of implementing IComparer<T>.
type BoxComp() =
    interface IComparer<Box> with
        // Compares by Height, Length, and Width.
        member _.Compare(x: Box, y: Box) =
            if x.Height.CompareTo(y.Height) <> 0 then
                x.Height.CompareTo(y.Height)
            elif x.Length.CompareTo(y.Length) <> 0 then
                x.Length.CompareTo(y.Length)
            elif x.Width.CompareTo(y.Width) <> 0 then
                x.Width.CompareTo(y.Width)
            else
                0

Imports System.Collections.Generic

Friend Class Program
    Shared Sub Main(ByVal args() As String)
        Dim Boxes As New List(Of Box)()
        Boxes.Add(New Box(4, 20, 14))
        Boxes.Add(New Box(12, 12, 12))
        Boxes.Add(New Box(8, 20, 10))
        Boxes.Add(New Box(6, 10, 2))
        Boxes.Add(New Box(2, 8, 4))
        Boxes.Add(New Box(2, 6, 8))
        Boxes.Add(New Box(4, 12, 20))
        Boxes.Add(New Box(18, 10, 4))
        Boxes.Add(New Box(24, 4, 18))
        Boxes.Add(New Box(10, 4, 16))
        Boxes.Add(New Box(10, 2, 10))
        Boxes.Add(New Box(6, 18, 2))
        Boxes.Add(New Box(8, 12, 4))
        Boxes.Add(New Box(12, 10, 8))
        Boxes.Add(New Box(14, 6, 6))
        Boxes.Add(New Box(16, 6, 16))
        Boxes.Add(New Box(2, 8, 12))
        Boxes.Add(New Box(4, 24, 8))
        Boxes.Add(New Box(8, 6, 20))
        Boxes.Add(New Box(18, 18, 12))

        ' Sort by an Comparer<T> implementation that sorts
        ' first by the length.
        Boxes.Sort(New BoxLengthFirst())

        Console.WriteLine("H - L - W")
        Console.WriteLine("==========")
        For Each bx As Box In Boxes
            Console.WriteLine("{0}" & vbTab & "{1}" & vbTab & "{2}", _
                              bx.Height.ToString(), bx.Length.ToString(), _
                              bx.Width.ToString())
        Next bx

        Console.WriteLine()
        Console.WriteLine("H - L - W")
        Console.WriteLine("==========")

        ' Get the default comparer that 
        ' sorts first by the height.
        Dim defComp As Comparer(Of Box) = Comparer(Of Box).Default

        ' Calling Boxes.Sort() with no parameter
        ' is the same as calling Boxs.Sort(defComp)
        ' because they are both using the default comparer.
        Boxes.Sort()

        For Each bx As Box In Boxes
            Console.WriteLine("{0}" & vbTab & "{1}" & vbTab & "{2}", _
                              bx.Height.ToString(), _
                              bx.Length.ToString(), _
                              bx.Width.ToString())
        Next bx


        ' This explicit interface implementation
        ' compares first by the length.
        ' Returns -1 because the length of BoxA
        ' is less than the length of BoxB.
        Dim LengthFirst As New BoxLengthFirst()

        Dim bc As Comparer(Of Box) = CType(LengthFirst, Comparer(Of Box))

        Dim BoxA As New Box(2, 6, 8)
        Dim BoxB As New Box(10, 12, 14)
        Dim x As Integer = LengthFirst.Compare(BoxA, BoxB)
        Console.WriteLine()
        Console.WriteLine(x.ToString())



    End Sub

End Class

Public Class BoxLengthFirst
    Inherits Comparer(Of Box)
    ' Compares by Length, Height, and Width.
    Public Overrides Function Compare(ByVal x As Box, ByVal y As Box) As Integer
        If x.Length.CompareTo(y.Length) <> 0 Then
            Return x.Length.CompareTo(y.Length)
        ElseIf x.Height.CompareTo(y.Height) <> 0 Then
            Return x.Height.CompareTo(y.Height)
        ElseIf x.Width.CompareTo(y.Width) <> 0 Then
            Return x.Width.CompareTo(y.Width)
        Else
            Return 0
        End If
    End Function

End Class

' This class is not demonstrated in the Main method
' and is provided only to show how to implement
' the interface. It is recommended to derive
' from Comparer<T> instead of implementing IComparer<T>.
Public Class BoxComp
    Implements IComparer(Of Box)
    ' Compares by Height, Length, and Width.
    Public Function Compare(ByVal x As Box, ByVal y As Box) As Integer Implements _
                                                IComparer(Of Box).Compare
        If x.Height.CompareTo(y.Height) <> 0 Then
            Return x.Height.CompareTo(y.Height)
        ElseIf x.Length.CompareTo(y.Length) <> 0 Then
            Return x.Length.CompareTo(y.Length)
        ElseIf x.Width.CompareTo(y.Width) <> 0 Then
            Return x.Width.CompareTo(y.Width)
        Else
            Return 0
        End If
    End Function
End Class

Public Class Box
    Implements IComparable(Of 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 privateHeight As Integer
    Public Property Height() As Integer
        Get
            Return privateHeight
        End Get
        Private Set(ByVal value As Integer)
            privateHeight = value
        End Set
    End Property
    Private privateLength As Integer
    Public Property Length() As Integer
        Get
            Return privateLength
        End Get
        Private Set(ByVal value As Integer)
            privateLength = value
        End Set
    End Property
    Private privateWidth As Integer
    Public Property Width() As Integer
        Get
            Return privateWidth
        End Get
        Private Set(ByVal value As Integer)
            privateWidth = value
        End Set
    End Property

    Public Function CompareTo(ByVal other As Box) As Integer _
                        Implements IComparable(Of Box).CompareTo
        ' Compares Height, Length, and Width.
        If Me.Height.CompareTo(other.Height) <> 0 Then
            Return Me.Height.CompareTo(other.Height)
        ElseIf Me.Length.CompareTo(other.Length) <> 0 Then
            Return Me.Length.CompareTo(other.Length)
        ElseIf Me.Width.CompareTo(other.Width) <> 0 Then
            Return Me.Width.CompareTo(other.Width)
        Else
            Return 0
        End If
    End Function

End Class

Hinweise

Leiten Sie diese Klasse ab, um eine benutzerdefinierte Implementierung der Schnittstelle für die IComparer<T> Verwendung mit Auflistungsklassen wie z. B. den SortedList<TKey,TValue> generischen SortedDictionary<TKey,TValue> Klassen bereitzustellen.

Der Unterschied zwischen der Ableitung von der Comparer<T> Klasse und der Implementierung der System.IComparable Schnittstelle lautet wie folgt:

• Um anzugeben, wie zwei Objekte standardmäßig verglichen werden sollen, implementieren Sie die System.IComparable Schnittstelle in Ihrer Klasse. Dadurch wird sichergestellt, dass Sortiervorgänge den von Ihnen bereitgestellten Standardvergleichscode verwenden.

• Um einen Vergleich zu definieren, der anstelle des Standardvergleichs verwendet werden soll, leiten Sie von der Comparer<T> Klasse ab. Anschließend können Sie diesen Vergleich in Sortiervorgängen verwenden, die einen Comparer als Parameter verwenden.

Das von der Default Eigenschaft zurückgegebene Objekt verwendet die System.IComparable<T> generische Schnittstelle (IComparable<T> in C#, IComparable(Of T) in Visual Basic), um zwei Objekte zu vergleichen. Wenn der Typ T die System.IComparable<T> generische Schnittstelle nicht implementiert, gibt die Default Eigenschaft eine Comparer<T> , die die System.IComparable Schnittstelle verwendet.

Hinweise für Ausführende

Compare(T, T) und verhält sich in Bezug auf Kulturempfindlichkeit und Equals(T, T) Groß-/Kleinschreibung unterschiedlich.

Für Zeichenfolgenvergleiche wird die StringComparer Klasse empfohlen Comparer<String>. Eigenschaften der StringComparer Klasse geben vordefinierte Instanzen zurück, die Zeichenfolgenvergleiche mit unterschiedlichen Kombinationen von Kulturempfindlichkeit und Groß-/Kleinschreibung durchführen. Die Groß-/Kleinschreibung und Kulturempfindlichkeit sind unter den Mitgliedern derselben StringComparer Instanz konsistent.

Weitere Informationen zu kulturspezifischen Vergleichen finden Sie unter Namespace System.Globalization und Globalisierung und Lokalisierung.

Weitere Informationen

• IComparer<T>
• IComparable<T>
• StringComparer
• CultureInfo