Action Action Action Action Delegate

定義

パラメーターを受け取らず、戻り値を持たないメソッドをカプセル化します。Encapsulates a method that has no parameters and does not return a value.

public delegate void Action();
public delegate void Action();
type Action = delegate of unit -> unit
Public Delegate Sub Action()
継承

注釈

このデリゲートを使用して、カスタム デリゲートを明示的に宣言することがなく、メソッドをパラメーターとして渡すことができます。You can use this delegate to pass a method as a parameter without explicitly declaring a custom delegate. カプセル化されるメソッドは、このデリゲートで定義されているメソッド シグネチャに対応する必要があります。The encapsulated method must correspond to the method signature that is defined by this delegate. これは、カプセル化するメソッドがパラメーターと戻り値が必要なことを意味します。This means that the encapsulated method must have no parameters and no return value. (C# のメソッドが返す必要がありますvoidします。(In C#, the method must return void. Visual basic で定義する必要があります、 Sub.End SubIn Visual Basic, it must be defined by the SubEnd Sub 構築します。construct. これは、ことができますが無視される値を返すメソッド。)通常、このようなメソッドは、操作の実行に使用されます。It can also be a method that returns a value that is ignored.) Typically, such a method is used to perform an operation.

注意

パラメーターを持たないして値を返すメソッドを参照するには、ジェネリックを使用Func<TResult>代わりにデリゲートします。To reference a method that has no parameters and returns a value, use the generic Func<TResult> delegate instead.

使用すると、Actionデリゲートがありませんをパラメーターなしのプロシージャをカプセル化するデリゲートを明示的に定義します。When you use the Action delegate, you do not have to explicitly define a delegate that encapsulates a parameterless procedure. たとえば、次のコードで明示的にという名前のデリゲートが宣言ShowValueへの参照を割り当てると、Name.DisplayToWindowインスタンス メソッドのデリゲートのインスタンスにします。For example, the following code explicitly declares a delegate named ShowValue and assigns a reference to the Name.DisplayToWindow instance method to its delegate instance.

using namespace System;
using namespace System::Windows::Forms;

public delegate void ShowValue();


public ref class Name
{
private:
   String^ instanceName;

public:
   Name(String^ name) 
   {
      instanceName = name;
   }

   void DisplayToConsole()
   {
      Console::WriteLine(this->instanceName);
   }

   void DisplayToWindow()
   {
      MessageBox::Show(this->instanceName);
   }
};

int main()
{
   Name^ testName = gcnew Name(L"Koani");
   ShowValue^ showMethod;
   showMethod = gcnew ShowValue(testName, &Name::DisplayToWindow);
   showMethod();
   return 0;
}
using System;
using System.Windows.Forms;

public delegate void ShowValue();

public class Name
{
   private string instanceName;
   
   public Name(string name)
   {
      this.instanceName = name;
   }

   public void DisplayToConsole()
   {
      Console.WriteLine(this.instanceName);
   }

   public void DisplayToWindow()
   {
      MessageBox.Show(this.instanceName);
   }
}

public class testTestDelegate
{
   public static void Main()
   {
      Name testName = new Name("Koani");
      ShowValue showMethod = testName.DisplayToWindow;
      showMethod();
   }
}
Public Delegate Sub ShowValue

Public Class Name
   Private instanceName As String
   
   Public Sub New(name As String)
      Me.instanceName = name
   End Sub
   
   Public Sub DisplayToConsole()
      Console.WriteLine(Me.instanceName)
   End Sub   
   
   Public Sub DisplayToWindow()
      MsgBox(Me.instanceName)
   End Sub   
End Class

Public Module testDelegate
   Public Sub Main()
      Dim testName As New Name("Koani")
      Dim showMethod As ShowValue = AddressOf testName.DisplayToWindow
      showMethod   
   End Sub
End Module

次の例では、インスタンス化してこのコードを簡略化、Action明示的に新しいデリゲートを定義して、名前付きメソッドをそこに割り当てる代わりにデリゲートします。The following example simplifies this code by instantiating the Action delegate instead of explicitly defining a new delegate and assigning a named method to it.

#using <System.Windows.Forms.dll>

using namespace System;
using namespace System::Windows::Forms;

public ref class Name
{
private:
   String^ instanceName;
   
public:
   Name(String^ name)
   {
      instanceName = name;
   }

   void DisplayToConsole()
   {
      Console::WriteLine(this->instanceName);
   }

   void DisplayToWindow()
   {
      MessageBox::Show(this->instanceName);
   }
};


int main()
{
   Name^ testName = gcnew Name(L"Koani");
   System::Action^ showMethod;
   showMethod += gcnew Action(testName, &Name::DisplayToWindow);
   showMethod();
   return 0;
}
using System;
using System.Windows.Forms;

public class Name
{
   private string instanceName;
   
   public Name(string name)
   {
      this.instanceName = name;
   }

   public void DisplayToConsole()
   {
      Console.WriteLine(this.instanceName);
   }

   public void DisplayToWindow()
   {
      MessageBox.Show(this.instanceName);
   }
}

public class testTestDelegate
{
   public static void Main()
   {
      Name testName = new Name("Koani");
      Action showMethod = testName.DisplayToWindow;
      showMethod();
   }
}
Public Class Name
   Private instanceName As String
   
   Public Sub New(name As String)
      Me.instanceName = name
   End Sub
   
   Public Sub DisplayToConsole()
      Console.WriteLine(Me.instanceName)
   End Sub   
   
   Public Sub DisplayToWindow()
      MsgBox(Me.instanceName)
   End Sub   
End Class

Public Module testDelegate
   Public Sub Main()
      Dim testName As New Name("Koani")
      Dim showMethod As Action = AddressOf testName.DisplayToWindow
      showMethod   
   End Sub
End Module

使用することも、Action次の例に示すように、c# の場合は、匿名メソッドを持つデリゲートします。You can also use the Action delegate with anonymous methods in C#, as the following example illustrates. (匿名メソッドの概要については、次を参照してください匿名メソッド。)。(For an introduction to anonymous methods, see Anonymous Methods.)

using System;
using System.Windows.Forms;

public class Name
{
   private string instanceName;
   
   public Name(string name)
   {
      this.instanceName = name;
   }

   public void DisplayToConsole()
   {
      Console.WriteLine(this.instanceName);
   }

   public void DisplayToWindow()
   {
      MessageBox.Show(this.instanceName);
   }
}

public class Anonymous
{
   public static void Main()
   {
      Name testName = new Name("Koani");
      Action showMethod = delegate() { testName.DisplayToWindow();} ;
      showMethod();
   }
}

ラムダ式を割り当てることができます、Action次の例に示すように、インスタンスを委任します。You can also assign a lambda expression to an Action delegate instance, as the following example illustrates. (ラムダ式の概要については、次を参照してくださいラムダ式。)。(For an introduction to lambda expressions, see Lambda Expressions.)

using System;
using System.Windows.Forms;

public class Name
{
   private string instanceName;
   
   public Name(string name)
   {
      this.instanceName = name;
   }

   public void DisplayToConsole()
   {
      Console.WriteLine(this.instanceName);
   }

   public void DisplayToWindow()
   {
      MessageBox.Show(this.instanceName);
   }
}

public class LambdaExpression
{
   public static void Main()
   {
      Name testName = new Name("Koani");
      Action showMethod = () => testName.DisplayToWindow();
      showMethod();
   }
}
Public Class Name
   Private instanceName As String
   
   Public Sub New(name As String)
      Me.instanceName = name
   End Sub
   
   Public Function DisplayToConsole() As Integer
      Console.WriteLine(Me.instanceName)
      Return 0
   End Function
   
   Public Function DisplayToWindow() As Integer
      Return MsgBox(Me.instanceName)
   End Function      
End Class

Module LambdaExpression
   Public Sub Main()
      Dim name1 As New Name("Koani")
      Dim methodCall As Action = Sub() name1.DisplayToWindow()
      methodCall()
   End Sub
End Module

拡張メソッド

GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate)

指定したデリゲートによって表されるメソッドを表すオブジェクトを取得します。Gets an object that represents the method represented by the specified delegate.

適用対象

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