.NET Framework Class Library IComparable<(Of <(T>)>) Interface Defines a generalized comparison method that a value type or class implements to create a type-specific comparison method for ordering instances. (in mscorlib.dll)
Syntax
Public Interface IComparable(Of In T)
public interface IComparable<in T>
generic<typename T>
public interface class IComparable
type IComparable<'T> = interface end
Type Parameters- in In in in T
The type of objects to compare. This type parameter is contravariant. That is, you can use either the type you specified or any type that is less derived. For more information about covariance and contravariance, see Covariance and Contravariance in Generics.
The IComparable<(Of <(T>)>) type exposes the following members.
Remarks
This interface is implemented by types whose values can be ordered; for example, the numeric and string classes. A value type or class implements the CompareTo(T) method to create a type-specific comparison method suitable for purposes such as sorting. The IComparable<(Of <(T>)>) interface defines the CompareTo(T) method, which determines the sort order of instances of the implementing type. The IEquatable<(Of <(T>)>) interface defines the Equals method, which determines the equality of instances of the implementing type. The implementation of the CompareTo(T) method must return an Int32 that has one of three values, as shown in the following table. Value | Meaning |
|---|
Less than zero | This object is less than the object specified by the CompareTo method. | Zero | This object is equal to the method parameter. | Greater than zero | This object is greater than the method parameter. |
The IComparable<(Of <(T>)>) interface provides a strongly typed comparison method for ordering members of a generic collection object. Because of this, it is usually not called directly from developer code. Instead, it is called automatically by methods such as List<(Of <(T>)>)..::.Sort()()() and Add. Notes to ImplementersReplace the type parameter of the IComparable<(Of <(T>)>) interface with the type that is implementing this interface.
Examples
The following code example illustrates the implementation of IComparable for a simple Temperature object. The example creates a SortedList<(Of <(TKey, TValue>)>) collection of strings with Temperature object keys, and adds several pairs of temperatures and strings to the list out of sequence. In the call to the Add method, the SortedList<(Of <(TKey, TValue>)>) collection uses the IComparable<(Of <(T>)>) implementation to sort the list entries, which are then displayed in order of increasing temperature.
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 kelvins As Double)
Me.Kelvin = kelvins
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.
'
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 kelvins)
{
this.Kelvin = kelvins;
}
}
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.
*/
#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 kelvins) {
this->Kelvin = kelvins;
}
};
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.
*/
Version Information
.NET FrameworkSupported in: 4, 3.5, 3.0, 2.0 .NET Framework Client ProfileSupported in: 4, 3.5 SP1 Portable Class LibrarySupported in: Portable Class Library
Platforms
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role not supported), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
See Also
|
.NET Framework クラス ライブラリ IComparable<(Of <(T>)>) インターフェイス インスタンスの並べ替えなどを目的とし、型固有の比較メソッドを作成するために値型またはクラスで実装する、汎用の比較メソッドを定義します。 (mscorlib.dll 内)
構文
Public Interface IComparable(Of In T)
public interface IComparable<in T>
generic<typename T>
public interface class IComparable
type IComparable<'T> = interface end
型パラメーター- in In in in T
比較するオブジェクトの型。 このパラメーターが反変の型パラメーターです。 つまり、その指定した型を使用するか、それよりも弱い任意の派生型を使用することができます。 共変性と反変性の詳細については、「ジェネリックの共変性と反変性」を参照してください。
IComparable<(Of <(T>)>) 型で公開されるメンバーは以下のとおりです。
メソッド
解説
このインターフェイスは、数値クラスや文字列クラスのように、値の順序を指定できる型によって実装されます。 値型やクラスは、CompareTo(T) メソッドを実装し、並べ替えなどの目的に適した型固有の比較メソッドを作成します。 IComparable<(Of <(T>)>) インターフェイスには、実装している型のインスタンスの並べ替え順序を決定する CompareTo(T) メソッドが定義されています。 IEquatable<(Of <(T>)>) インターフェイスには、実装している型のインスタンスの等価性を決定する Equals メソッドが定義されています。 CompareTo(T) メソッドの実装は、次の表に示すように、3 つの値のいずれかを持つ Int32 を返す必要があります。 値 | 説明 |
|---|
number < 0 | このオブジェクトは、CompareTo メソッドで指定されたオブジェクトを下回ります。 | 0 | このオブジェクトは、メソッドのパラメーターと同じです。 | ゼロより大 | このオブジェクトは、メソッドのパラメーターを上回ります。 |
IComparable<(Of <(T>)>) インターフェイスには、ジェネリック コレクション オブジェクトのメンバーを並べ替えるための、厳密に型指定された比較メソッドが用意されています。 このため、これは開発者のコードから通常直接呼び出されることはありません。 その代わりに、これは List<(Of <(T>)>)..::.Sort()()() や Add などのメソッドにより自動的に呼び出されます。 実装時の注意IComparable<(Of <(T>)>) インターフェイスの型パラメーターを、このインターフェイスを実装する型に置き換えます。
例
簡単な Temperature オブジェクトに IComparable を実装するコード例を次に示します。 この例では、Temperature オブジェクトのキーを保持する文字列の SortedList<(Of <(TKey, TValue>)>) コレクションを作成し、気温と文字列から成る複数のペアをランダムにリストに追加します。 Add メソッドの呼び出しでは、SortedList<(Of <(TKey, TValue>)>) コレクションで IComparable<(Of <(T>)>) の実装を使用してリストのエントリが並べ替えられ、気温の昇順で表示されます。
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 kelvins As Double)
Me.Kelvin = kelvins
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.
'
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 kelvins)
{
this.Kelvin = kelvins;
}
}
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.
*/
#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 kelvins) {
this->Kelvin = kelvins;
}
};
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.
*/
バージョン情報
.NET Frameworkサポート対象: 4、3.5、3.0、2.0 .NET Framework Client Profileサポート対象: 4、3.5 SP1 サポート対象:
プラットフォーム
Windows 7, Windows Vista SP1 以降, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core はサポート対象外), Windows Server 2008 R2 (SP1 以降で Server Core をサポート), Windows Server 2003 SP2
.NET Framework では、各プラットフォームのすべてのバージョンはサポートしていません。 サポートされているバージョンについては、「.NET Framework システム要件」を参照してください。
参照
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