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

Definition

Kapselt eine Methode, die über drei Parameter verfügt und keinen Wert zurückgibt.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)

Typparameter

T1

Der Typ des ersten Parameters der Methode, die dieser Delegat kapselt.The type of the first parameter of the method that this delegate encapsulates.

T2

Der Typ des zweiten Parameters der Methode, die dieser Delegat kapselt.The type of the second parameter of the method that this delegate encapsulates.

T3

Der Typ des dritten Parameters der Methode, die dieser Delegat kapselt.The type of the third parameter of the method that this delegate encapsulates.

Parameter

arg1

Der erste Parameter der Methode, die dieser Delegat kapselt.The first parameter of the method that this delegate encapsulates.

arg2

Der zweite Parameter der Methode, die dieser Delegat kapselt.The second parameter of the method that this delegate encapsulates.

arg3

Der dritte Parameter der Methode, die dieser Delegat kapselt.The third parameter of the method that this delegate encapsulates.

Vererbung
Action<T1,T2,T3>Action<T1,T2,T3>Action<T1,T2,T3>Action<T1,T2,T3>

Hinweise

Sie können die Action<T1,T2,T3> Delegat, der eine Methode als Parameter übergeben werden, ohne explizit einen benutzerdefinierten Delegaten zu deklarieren.You can use the Action<T1,T2,T3> delegate to pass a method as a parameter without explicitly declaring a custom delegate. Die der gekapselte Methode muss die Signatur der Methode entsprechen, die von diesem Delegaten definiert ist.The encapsulated method must correspond to the method signature that is defined by this delegate. Dies bedeutet, dass die gekapselte Methode zunächst drei Parameter, die alle an ihn als Wert übergeben werden, müssen sie keinen Wert zurück.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. (In C# muss die Methode zurückgeben void.(In C#, the method must return void. In Visual Basic muss es vom definiert werden die Sub...End SubIn Visual Basic, it must be defined by the SubEnd Sub erstellen.construct. Sie können auch eine Methode, die einen Wert zurückgibt, der ignoriert wird sein.) In der Regel wird eine solche Methode zum Ausführen eines Vorgangs verwendet.It can also be a method that returns a value that is ignored.) Typically, such a method is used to perform an operation.

Hinweis

Um eine Methode zu verweisen, die über drei Parameter verfügt und einen Wert zurückgibt, verwenden Sie den generischen Func<T1,T2,T3,TResult> stattdessen delegieren.To reference a method that has three parameters and returns a value, use the generic Func<T1,T2,T3,TResult> delegate instead.

Bei Verwendung der Action<T1,T2,T3> Delegaten, Sie müssen nicht explizit einen Delegaten definieren, die eine Methode mit drei Parametern kapselt.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. Der folgende Code deklariert beispielsweise explizit einen Delegaten, der mit dem Namen StringCopy und weist einen Verweis auf die CopyStrings Methode, um eine Delegatinstanz.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

Im folgende Beispiel wird dieser Code vereinfacht, durch die Instanziierung der Action<T1,T2,T3> Delegaten aufrufen, anstatt explizit definieren einen neuen Delegaten und eine benannte Methode zugewiesen wird.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

Sie können auch die Action<T1,T2,T3> delegieren mit anonymen Methoden in C# geschrieben, wie im folgende Beispiel veranschaulicht.You can also use the Action<T1,T2,T3> delegate with anonymous methods in C#, as the following example illustrates. (Eine Einführung in anonyme Methoden, finden Sie unter anonyme Methoden.)(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]);
   }
}

Sie können auch einen Lambda-Ausdruck zuweisen einer Action<T1,T2,T3> Instanz delegieren, wie im folgende Beispiel veranschaulicht.You can also assign a lambda expression to an Action<T1,T2,T3> delegate instance, as the following example illustrates. (Eine Einführung in Lambda-Ausdrücke, finden Sie unter Lambda-Ausdrücke.)(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

Extension Methods

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

Ruft ein Objekt ab, das die Methode darstellt, die vom angegebenen Delegaten dargestellt wird.Gets an object that represents the method represented by the specified delegate.

Gilt für:

Siehe auch