EventArgs Class

Definition

Namespace:
System
Assembly:
System.Runtime.dll
Assembly:
mscorlib.dll
Assembly:
netstandard.dll

Stellt die Basisklasse für Klassen dar, die Ereignisdaten enthalten, und stellt einen Wert für Ereignisse bereit, die keine Daten enthalten.Represents the base class for classes that contain event data, and provides a value to use for events that do not include event data.

public ref class EventArgs
public class EventArgs
[System.Serializable]
public class EventArgs
[System.Runtime.InteropServices.ComVisible(true)]
[System.Serializable]
public class EventArgs
type EventArgs = class
Public Class EventArgs
Inheritance
Object
EventArgs
Derived
Attributes
ComVisibleAttribute SerializableAttribute

Examples

Das folgende Beispiel zeigt eine benutzerdefinierte Ereignisdaten Klasse mit dem Namen ThresholdReachedEventArgs, die von der EventArgs-Klasse abgeleitet wird.The following example shows a custom event data class named ThresholdReachedEventArgs that derives from the EventArgs class. Eine Instanz der Ereignisdaten Klasse wird an den Ereignishandler für das ThresholdReached-Ereignis übermittelt.An instance of the event data class is passed to the event handler for the ThresholdReached event.

using namespace System;

public ref class ThresholdReachedEventArgs : public EventArgs
{
   public:
      property int Threshold;
      property DateTime TimeReached;
};

public ref class Counter
{
   private:
      int threshold;
      int total;

   public:
      Counter() {};

      Counter(int passedThreshold)
      {
         threshold = passedThreshold;
      }

      void Add(int x)
      {
          total += x;
          if (total >= threshold) {
             ThresholdReachedEventArgs^ args = gcnew ThresholdReachedEventArgs();
             args->Threshold = threshold;
             args->TimeReached = DateTime::Now;
             OnThresholdReached(args);
          }
      }

      event EventHandler<ThresholdReachedEventArgs^>^ ThresholdReached;

   protected:
      virtual void OnThresholdReached(ThresholdReachedEventArgs^ e)
      {
         ThresholdReached(this, e);
      }
};

public ref class SampleHandler
{
   public:
      static void c_ThresholdReached(Object^ sender, ThresholdReachedEventArgs^ e)
      {
         Console::WriteLine("The threshold of {0} was reached at {1}.",
                            e->Threshold,  e->TimeReached);
         Environment::Exit(0);
      }
};

void main()
{
   Counter^ c = gcnew Counter((gcnew Random())->Next(10));
   c->ThresholdReached += gcnew EventHandler<ThresholdReachedEventArgs^>(SampleHandler::c_ThresholdReached);

   Console::WriteLine("press 'a' key to increase total");
   while (Console::ReadKey(true).KeyChar == 'a') {
      Console::WriteLine("adding one");
      c->Add(1);
   }
}

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Counter c = new Counter(new Random().Next(10));
            c.ThresholdReached += c_ThresholdReached;

            Console.WriteLine("press 'a' key to increase total");
            while (Console.ReadKey(true).KeyChar == 'a')
            {
                Console.WriteLine("adding one");
                c.Add(1);
            }
        }

        static void c_ThresholdReached(object sender, ThresholdReachedEventArgs e)
        {
            Console.WriteLine("The threshold of {0} was reached at {1}.", e.Threshold,  e.TimeReached);
            Environment.Exit(0);
        }
    }

    class Counter
    {
        private int threshold;
        private int total;

        public Counter(int passedThreshold)
        {
            threshold = passedThreshold;
        }

        public void Add(int x)
        {
            total += x;
            if (total >= threshold)
            {
                ThresholdReachedEventArgs args = new ThresholdReachedEventArgs();
                args.Threshold = threshold;
                args.TimeReached = DateTime.Now;
                OnThresholdReached(args);
            }
        }

        protected virtual void OnThresholdReached(ThresholdReachedEventArgs e)
        {
            EventHandler<ThresholdReachedEventArgs> handler = ThresholdReached;
            if (handler != null)
            {
                handler(this, e);
            }
        }

        public event EventHandler<ThresholdReachedEventArgs> ThresholdReached;
    }

    public class ThresholdReachedEventArgs : EventArgs
    {
        public int Threshold { get; set; }
        public DateTime TimeReached { get; set; }
    }
}

Module Module1

    Sub Main()
        Dim c As Counter = New Counter(New Random().Next(10))
        AddHandler c.ThresholdReached, AddressOf c_ThresholdReached

        Console.WriteLine("press 'a' key to increase total")
        While Console.ReadKey(True).KeyChar = "a"
            Console.WriteLine("adding one")
            c.Add(1)
        End While
    End Sub

    Sub c_ThresholdReached(sender As Object, e As ThresholdReachedEventArgs)
        Console.WriteLine("The threshold of {0} was reached at {1}.", e.Threshold, e.TimeReached)
        Environment.Exit(0)
    End Sub
End Module

Class Counter
    Private threshold As Integer
    Private total As Integer

    Public Sub New(passedThreshold As Integer)
        threshold = passedThreshold
    End Sub

    Public Sub Add(x As Integer)
        total = total + x
        If (total >= threshold) Then
            Dim args As ThresholdReachedEventArgs = New ThresholdReachedEventArgs()
            args.Threshold = threshold
            args.TimeReached = DateTime.Now
            OnThresholdReached(args)
        End If
    End Sub

    Protected Overridable Sub OnThresholdReached(e As ThresholdReachedEventArgs)
        RaiseEvent ThresholdReached(Me, e)
    End Sub

    Public Event ThresholdReached As EventHandler(Of ThresholdReachedEventArgs)
End Class

Class ThresholdReachedEventArgs
    Inherits EventArgs

    Public Property Threshold As Integer
    Public Property TimeReached As DateTime
End Class

Remarks

Diese Klasse dient als Basisklasse für alle Klassen, die Ereignisdaten darstellen.This class serves as the base class for all classes that represent event data. Beispielsweise wird die System.AssemblyLoadEventArgs-Klasse von EventArgs abgeleitet und zum Speichern der Daten für assemblyauslastungs-Ereignisse verwendet.For example, the System.AssemblyLoadEventArgs class derives from EventArgs and is used to hold the data for assembly load events. Wenn Sie eine benutzerdefinierte Ereignisdaten Klasse erstellen möchten, erstellen Sie eine Klasse, die von der EventArgs-Klasse abgeleitet wird, und stellen Sie die Eigenschaften zum Speichern der erforderlichen Daten bereitTo create a custom event data class, create a class that derives from the EventArgs class and provide the properties to store the necessary data. Der Name der benutzerdefinierten Ereignisdaten Klasse sollte mit EventArgsenden.The name of your custom event data class should end with EventArgs.

Um ein Objekt zu übergeben, das keine Daten enthält, verwenden Sie das Empty-Feld.To pass an object that does not contain any data, use the Empty field.

Weitere Informationen zu Ereignissen finden Sie im Artikel Behandlung und Auswerfen von Ereignissen .For more information about events, see the Handling and Raising Events article.

Constructors

EventArgs()

Initialisiert eine neue Instanz der Klasse EventArgs.Initializes a new instance of the EventArgs class.

Fields

Empty

Stellt einen zu verwendenden Wert für Ereignisse, die keine Ereignisdaten haben.Provides a value to use with events that do not have event data.

Methods

Equals(Object)

Bestimmt, ob das angegebene Objekt mit dem aktuellen Objekt identisch ist.Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetHashCode()

Fungiert als Standardhashfunktion.Serves as the default hash function.

(Inherited from Object)
GetType()

Ruft den Type der aktuellen Instanz ab.Gets the Type of the current instance.

(Inherited from Object)
MemberwiseClone()

Erstellt eine flache Kopie des aktuellen Object.Creates a shallow copy of the current Object.

(Inherited from Object)
ToString()

Gibt eine Zeichenfolge zurück, die das aktuelle Objekt darstellt.Returns a string that represents the current object.

(Inherited from Object)

Applies to

See also