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)
以下示例从
Comparer<T>
类
BoxLengthFirst
派生类。 此比较器比较类型
Box
为两个对象。 它首先按长度、高度和宽度对它们进行排序。 该
Box
类实现
IComparable<T>
接口来控制两个
Box
对象之间的默认比较。 此默认实现先按高度排序，再按长度排序，然后按宽度排序。 该示例通过先使用
BoxLengthFirst
比较器对对象列表
Box
进行排序，然后使用默认比较器来显示这两个比较之间的差异。
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);
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);
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);
return 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)
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)
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
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
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
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)
Return 0
End If
End Function
End Class
派生自此类，以提供用于集合类（如
SortedList<TKey,TValue>
泛
SortedDictionary<TKey,TValue>
型类）的接口的自定义实现
IComparer<T>
。
从
Comparer<T>
类派生和实现
System.IComparable
接口之间的区别如下：
若要指定默认情况下应如何比较两个对象，请在类中实现
System.IComparable
接口。 这可确保排序操作将使用你提供的默认比较代码。
若要定义要使用的比较器而不是默认比较器，请派生自
Comparer<T>
类。 然后，可以在将比较器作为参数的排序操作中使用此比较器。
属性返回
Default
的对象使用
System.IComparable<T>
C# 中的泛型接口 (
IComparable<T>
，
IComparable(Of T)
Visual Basic) 比较两个对象。 如果类型
T
不实现
System.IComparable<T>
泛型接口，则
Default
属性返回使用该接口的
System.IComparable
接口
Comparer<T>
。
实施者说明
Compare(T, T)
在
Equals(T, T)
区域性敏感度和区分大小写方面的行为可能有所不同。
对于字符串比较，
StringComparer
建议对
CompareerString<>
使用类。
StringComparer
类的属性返回预定义实例，这些实例使用区域性敏感度和区分大小写的不同组合执行字符串比较。 区分大小写和区域性敏感度在同一
StringComparer
实例的成员之间保持一致。
有关特定于区域性的比较的详细信息，请参阅
System.Globalization
命名空间
和全球化和本地化
。
