IComparable 泛型接口

IComparable 泛型接口

注意：此接口在 .NET Framework 2.0 版中是新增的。

定义由值类型或类实现的通用的比较方法，以为排序实例创建类型特定的比较方法。

命名空间:System
程序集:mscorlib（在 mscorlib.dll 中）

 语法

Visual Basic（声明）

Public Interface IComparable(Of T)

Visual Basic（用法）

Dim instance As IComparable(Of T)

C#

public interface IComparable<T>

C++

generic<typename T>
public interface class IComparable

J#

J# 支持使用泛型类型和方法，但不支持进行新的声明。

JScript

JScript 支持泛型类型和方法。

 备注

此接口由值可以排序的类型实现；例如数值或字符串类。值类型或类实现 CompareTo 方法以创建适合排序等目的的类型特定的比较方法。

注意

IComparable 接口定义 CompareTo 方法，该方法确定实现类型的实例的排序顺序。IEquatable 接口定义 Equals 方法，该方法确定实现类型的实例的相等性。

给实现者的说明 用实现此接口的类型替换 IComparable 接口的类型参数。

 示例

下面的代码示例演示一个简单的 Temperature 对象的 IComparable 实现。该示例创建带有 Temperature 对象键的字符串的 SortedList 集合，并将多个温度和字符串对添加到无序列表中。SortedList 集合使用 IComparable 实现对列表项进行排序，然后，这些列表项将按温度的升序显示。

Visual Basic

复制代码

Imports System
Imports System.Collections.Generic
Public Class Temperature
Implements IComparable(Of Temperature)
' Implement the generic CompareTo method. In the Implements statement,
' specify the Temperature class for the type parameter of the
' generic IComparable interface. Use that type for the parameter
' of the CompareTo method.
'
Public Overloads Function CompareTo(ByVal other As Temperature) As Integer _
Implements IComparable(Of Temperature).CompareTo
' The temperature comparison depends on the comparison of the
' the underlying Double values. Because the CompareTo method is
' strongly typed, it is not necessary to test for the correct
' object type.
Return m_value.CompareTo(other.m_value)
End Function
' The underlying temperature value.
Protected m_value As Double = 0.0
Public ReadOnly Property Celsius() As Double
Get
Return m_value - 273.15
End Get
End Property
Public Property Kelvin() As Double
Get
Return m_value
End Get
Set(ByVal Value As Double)
If value < 0.0 Then
Throw New ArgumentException("Temperature cannot be less than absolute zero.")
Else
m_value = Value
End If
End Set
End Property
Public Sub New(ByVal degreesKelvin As Double)
Me.Kelvin = degreesKelvin
End Sub
End Class
Public Class Example
Public Shared Sub Main()
Dim temps As New SortedList(Of Temperature, String)
' Add entries to the sorted list, out of order.
temps.Add(New Temperature(2017.15), "Boiling point of Lead")
temps.Add(New Temperature(0), "Absolute zero")
temps.Add(New Temperature(273.15), "Freezing point of water")
temps.Add(New Temperature(5100.15), "Boiling point of Carbon")
temps.Add(New Temperature(373.15), "Boiling point of water")
temps.Add(New Temperature(600.65), "Melting point of Lead")
For Each kvp As KeyValuePair(Of Temperature, String) In temps
Console.WriteLine("{0} is {1} degrees Celsius.", kvp.Value, kvp.Key.Celsius)
Next
End Sub
End Class
' This code example produces the following output:
'
'Absolute zero is -273.15 degrees Celsius.
'Freezing point of water is 0 degrees Celsius.
'Boiling point of water is 100 degrees Celsius.
'Melting point of Lead is 327.5 degrees Celsius.
'Boiling point of Lead is 1744 degrees Celsius.
'Boiling point of Carbon is 4827 degrees Celsius.
'

C#

复制代码

using System;
using System.Collections.Generic;
public class Temperature : IComparable<Temperature>
{
// Implement the CompareTo method. For the parameter type, Use 
// the type specified for the type parameter of the generic 
// IComparable interface. 
//
public int CompareTo(Temperature other)
{
// The temperature comparison depends on the comparison of the
// the underlying Double values. Because the CompareTo method is
// strongly typed, it is not necessary to test for the correct
// object type.
return m_value.CompareTo(other.m_value);
}
// The underlying temperature value.
protected double m_value = 0.0;
public double Celsius
{
get
{
return m_value - 273.15;
}
}
public double Kelvin
{
get
{
return m_value;
}
set
{
if (value < 0.0)
{
throw new ArgumentException("Temperature cannot be less than absolute zero.");
}
else
{
m_value = value;
}
}
}
public Temperature(double degreesKelvin)
{
this.Kelvin = degreesKelvin;
}
}
public class Example
{
public static void Main()
{
SortedList<Temperature, string> temps =
new SortedList<Temperature, string>();
// Add entries to the sorted list, out of order.
temps.Add(new Temperature(2017.15), "Boiling point of Lead");
temps.Add(new Temperature(0), "Absolute zero");
temps.Add(new Temperature(273.15), "Freezing point of water");
temps.Add(new Temperature(5100.15), "Boiling point of Carbon");
temps.Add(new Temperature(373.15), "Boiling point of water");
temps.Add(new Temperature(600.65), "Melting point of Lead");
foreach( KeyValuePair<Temperature, string> kvp in temps )
{
Console.WriteLine("{0} is {1} degrees Celsius.", kvp.Value, kvp.Key.Celsius);
}
}
}
/* This code example produces the following output:
Absolute zero is -273.15 degrees Celsius.
Freezing point of water is 0 degrees Celsius.
Boiling point of water is 100 degrees Celsius.
Melting point of Lead is 327.5 degrees Celsius.
Boiling point of Lead is 1744 degrees Celsius.
Boiling point of Carbon is 4827 degrees Celsius.
*/

C++

复制代码

#using <System.dll>
using namespace System;
using namespace System::Collections::Generic;
public ref class Temperature: public IComparable<Temperature^> {
protected:
// The value holder
Double m_value;
public:
// Implement the CompareTo method. For the parameter type, Use 
// the type specified for the type parameter of the generic 
// IComparable interface. 
//
virtual Int32 CompareTo( Temperature^ other ) {
// The temperature comparison depends on the comparison of the
// the underlying Double values. Because the CompareTo method is
// strongly typed, it is not necessary to test for the correct
// object type.
return m_value.CompareTo( other->m_value );
}
property Double Celsius {
Double get() {
return m_value + 273.15;
}
}
property Double Kelvin {
Double get() {
return m_value;
}
void set( Double value ) {
if (value < 0)
throw gcnew ArgumentException("Temperature cannot be less than absolute zero.");
else
m_value = value;
}
}
Temperature(Double degreesKelvin) {
this->Kelvin = degreesKelvin;
}
};
int main() {
SortedList<Temperature^, String^>^ temps =
gcnew SortedList<Temperature^, String^>();
// Add entries to the sorted list, out of order.
temps->Add(gcnew Temperature(2017.15), "Boiling point of Lead");
temps->Add(gcnew Temperature(0), "Absolute zero");
temps->Add(gcnew Temperature(273.15), "Freezing point of water");
temps->Add(gcnew Temperature(5100.15), "Boiling point of Carbon");
temps->Add(gcnew Temperature(373.15), "Boiling point of water");
temps->Add(gcnew Temperature(600.65), "Melting point of Lead");
for each( KeyValuePair<Temperature^, String^>^ kvp in temps )
{
Console::WriteLine("{0} is {1} degrees Celsius.", kvp->Value, kvp->Key->Celsius);
}
}
/* This code example productes the following output:
Absolute zero is 273.15 degrees Celsius.
Freezing point of water is 546.3 degrees Celsius.
Boiling point of water is 646.3 degrees Celsius.
Melting point of Lead is 873.8 degrees Celsius.
Boiling point of Lead is 2290.3 degrees Celsius.
Boiling point of Carbon is 5373.3 degrees Celsius.
*/

 平台

Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition

.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。