Action<T1,T2,T3> Action<T1,T2,T3> Action<T1,T2,T3> Action<T1,T2,T3> Delegate

定義

3 つのパラメーターを受け取り、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 three parameters and does not return a value.

generic <typename T1, typename T2, typename T3>
public delegate void Action(T1 arg1, T2 arg2, T3 arg3);
public delegate void Action<in T1,in T2,in T3>(T1 arg1, T2 arg2, T3 arg3);
type Action<'T1, 'T2, 'T3> = delegate of 'T1 * 'T2 * 'T3 -> unit
Public Delegate Sub Action(Of In T1, In T2, In T3)(arg1 As T1, arg2 As T2, arg3 As T3)

型パラメーター

T1

このデリゲートによってカプセル化されるメソッドの最初のパラメーターの型。The type of the first parameter of the method that this delegate encapsulates.

T2

このデリゲートによってカプセル化されるメソッドの第 2 パラメーターの型。The type of the second parameter of the method that this delegate encapsulates.

T3

このデリゲートによってカプセル化されるメソッドの第 3 パラメーターの型。The type of the third parameter of the method that this delegate encapsulates.

パラメーター

arg1

このデリゲートによってカプセル化されるメソッドの最初のパラメーター。The first parameter of the method that this delegate encapsulates.

arg2

このデリゲートによってカプセル化されるメソッドの 2 番目のパラメーター。The second parameter of the method that this delegate encapsulates.

arg3

このデリゲートによってカプセル化されるメソッドの 3 番目のパラメーター。The third parameter of the method that this delegate encapsulates.

継承
Action<T1,T2,T3>Action<T1,T2,T3>Action<T1,T2,T3>Action<T1,T2,T3>

注釈

Action<T1,T2,T3>デリゲートを使用すると、カスタムデリゲートを明示的に宣言せずに、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 the Action<T1,T2,T3> delegate to pass a method as a parameter without explicitly declaring a custom delegate. カプセル化されたメソッドは、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している必要があります。The encapsulated method must correspond to the method signature that is defined by this delegate. つまり、カプセル化されたメソッドには、すべて値によって渡された3つのパラメーターが必要であり、値を返さないようにする必要があります。This means that the encapsulated method must have three parameters that are all passed to it by value, and it must not return a value. (でC#は、メソッドはをvoid返す必要があります。(In C#, the method must return void. Visual Basic では、 Subこれを定義する必要があります...End SubIn Visual Basic, it must be defined by the SubEnd Sub 構築.construct. また、無視される値を返すメソッドを指定することもできます)。通常、このようなメソッドは、操作を実行するために使用されます。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

3つのパラメーターを持ち、値を返すメソッドを参照するにはFunc<T1,T2,T3,TResult> 、代わりに汎用デリゲートを使用します。To reference a method that has three parameters and returns a value, use the generic Func<T1,T2,T3,TResult> delegate instead.

Action<T1,T2,T3>デリゲートを使用する場合、3つのパラメーターを持つメソッドをカプセル化するデリゲートを明示的に定義する必要はありません。When you use the Action<T1,T2,T3> delegate, you do not have to explicitly define a delegate that encapsulates a method with three parameters. たとえば、次のコードでは、という名前StringCopyのデリゲートを明示的にCopyStrings宣言し、メソッドへの参照をそのデリゲートインスタンスに割り当てます。For example, the following code explicitly declares a delegate named StringCopy and assigns a reference to the CopyStrings method to its delegate instance.

using System;

delegate void StringCopy(string[] stringArray1, 
                         string[] stringArray2, 
                         int indexToStart);
                         
public class TestDelegate
{
   public static void Main()
   {
      string[] ordinals = {"First", "Second", "Third", "Fourth", "Fifth"};
      string[] copiedOrdinals = new string[ordinals.Length];           
      StringCopy copyOperation = CopyStrings;
      copyOperation(ordinals, copiedOrdinals, 3);
      foreach (string ordinal in copiedOrdinals)
         Console.WriteLine(String.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
   }

   private static void CopyStrings(string[] source, string[] target, int startPos)
   {
      if (source.Length != target.Length) 
         throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");

      for (int ctr = startPos; ctr <= source.Length - 1; ctr++)
         target[ctr] = String.Copy(source[ctr]);
   }

}
Delegate Sub StringCopy(stringArray1() As String, _
                        stringArray2() As String, _
                        indexToStart As Integer)

Module TestDelegate
   Public Sub Main()
      Dim ordinals() As String = {"First", "Second", "Third", "Fourth", "Fifth"}
      Dim copiedOrdinals(ordinals.Length - 1) As String
      Dim copyOperation As StringCopy = AddressOf CopyStrings
      copyOperation(ordinals, copiedOrdinals, 3)
      For Each ordinal As String In copiedOrdinals
         Console.WriteLine(ordinal)
      Next    
   End Sub
   
   Private Sub CopyStrings(source() As String, target() As String, startPos As Integer)
      If source.Length <> target.Length Then 
         Throw New IndexOutOfRangeException("The source and target arrays must have the same number of elements.")
      End If
      For ctr As Integer = startPos to source.Length - 1
         target(ctr) = String.Copy(source(ctr))
      Next
   End Sub
End Module

次の例では、新しいデリゲートをAction<T1,T2,T3>明示的に定義し、名前付きメソッドを割り当てるのではなく、デリゲートをインスタンス化することによって、このコードを簡略化します。The following example simplifies this code by instantiating the Action<T1,T2,T3> delegate instead of explicitly defining a new delegate and assigning a named method to it.

using System;
                         
public class TestAction3
{
   public static void Main()
   {
      string[] ordinals = {"First", "Second", "Third", "Fourth", "Fifth"};
      string[] copiedOrdinals = new string[ordinals.Length];           
      Action<string[], string[], int> copyOperation = CopyStrings;
      copyOperation(ordinals, copiedOrdinals, 3);
      foreach (string ordinal in copiedOrdinals)
         Console.WriteLine(String.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
   }

   private static void CopyStrings(string[] source, string[] target, int startPos)
   {
      if (source.Length != target.Length) 
         throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");

      for (int ctr = startPos; ctr <= source.Length - 1; ctr++)
         target[ctr] = String.Copy(source[ctr]);
   }
}
Module TestAction3
   Public Sub Main()
      Dim ordinals() As String = {"First", "Second", "Third", "Fourth", "Fifth"}
      Dim copiedOrdinals(ordinals.Length - 1) As String
      Dim copyOperation As Action(Of String(), String(), Integer) = AddressOf CopyStrings
      copyOperation(ordinals, copiedOrdinals, 3)
      For Each ordinal As String In copiedOrdinals
         Console.WriteLine(ordinal)
      Next    
   End Sub
   
   Private Sub CopyStrings(source() As String, target() As String, startPos As Integer)
      If source.Length <> target.Length Then 
         Throw New IndexOutOfRangeException("The source and target arrays must have the same number of elements.")
      End If
      For ctr As Integer = startPos to source.Length - 1
         target(ctr) = String.Copy(source(ctr))
      Next
   End Sub
End Module

次の例に示すAction<T1,T2,T3>ようにC#、の匿名メソッドでデリゲートを使用することもできます。You can also use the Action<T1,T2,T3> 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、「匿名メソッド」を参照してください)。(For an introduction to anonymous methods, see Anonymous Methods.)

using System;
                         
public class TestAnon
{
   public static void Main()
   {
      string[] ordinals = {"First", "Second", "Third", "Fourth", "Fifth"};
      string[] copiedOrdinals = new string[ordinals.Length];           
      Action<string[], string[], int> copyOperation = delegate(string[] s1, 
                                                               string[] s2, 
                                                               int pos) 
                                      { CopyStrings(s1, s2, pos); };
      copyOperation(ordinals, copiedOrdinals, 3);
      foreach (string ordinal in copiedOrdinals)
         Console.WriteLine(String.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
   }

   private static void CopyStrings(string[] source, string[] target, int startPos)
   {
      if (source.Length != target.Length) 
         throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");

      for (int ctr = startPos; ctr <= source.Length - 1; ctr++)
         target[ctr] = String.Copy(source[ctr]);
   }
}

次の例に示すように、ラムダAction<T1,T2,T3>式をデリゲートインスタンスに割り当てることもできます。You can also assign a lambda expression to an Action<T1,T2,T3> delegate instance, as the following example illustrates. (ラムダ式の概要については、「ラムダ式」を参照してください)。(For an introduction to lambda expressions, see Lambda Expressions.)

using System;
                         
public class TestLambda
{
   public static void Main()
   {
      string[] ordinals = {"First", "Second", "Third", "Fourth", "Fifth"};
      string[] copiedOrdinals = new string[ordinals.Length];           
      Action<string[], string[], int> copyOperation = (s1, s2, pos) =>
                                      CopyStrings(s1, s2, pos); 
      copyOperation(ordinals, copiedOrdinals, 3);
      foreach (string ordinal in copiedOrdinals)
         Console.WriteLine(ordinal == string.Empty ? "<None>" : ordinal);
   }

   private static void CopyStrings(string[] source, string[] target, int startPos)
   {
      if (source.Length != target.Length) 
         throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");

      for (int ctr = startPos; ctr <= source.Length - 1; ctr++)
         target[ctr] = String.Copy(source[ctr]);
   }
}
Public Module TestLambda
   Public Sub Main()
      Dim ordinals() As String = {"First", "Second", "Third", "Fourth", "Fifth"}
      Dim copiedOrdinals(ordinals.Length - 1) As String           
      Dim copyOperation As Action(Of String(), String(), Integer) = _
                           Sub(s1, s2, pos) CopyStrings(s1, s2, pos) 
      copyOperation(ordinals, copiedOrdinals, 3)
      For Each ordinal As String In copiedOrdinals
         If String.IsNullOrEmpty(ordinal) Then
            Console.WriteLine("<None>")
         Else
            Console.WriteLine(ordinal)
         End If      
      Next   
   End Sub

   Private Function CopyStrings(source() As String, target() As String, startPos As Integer) As Integer
      If source.Length <> target.Length Then 
         Throw New IndexOutOfRangeException("The source and target arrays must have the same number of elements.")
      End If
      
      For ctr As Integer = startPos To source.Length - 1 
         target(ctr) = String.Copy(source(ctr))
      Next
      Return source.Length - startPos 
   End Function
End Module
' The example displays the following output:
'       Fourth
'       Fifth

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

こちらもご覧ください