Timer.Enabled Proprietà

Definizione

Spazio dei nomi:

System.Timers

Assembly:

System.ComponentModel.TypeConverter.dll

Origine:

Timer.cs

Ottiene o imposta un valore che indica se Timer deve generare l'evento Elapsed.

public:
 property bool Enabled { bool get(); void set(bool value); };

public bool Enabled { get; set; }

member this.Enabled : bool with get, set

Public Property Enabled As Boolean

Valore della proprietà

Boolean

true se Timer deve generare l'evento Elapsed; in caso contrario, false. Il valore predefinito è false.

Eccezioni

ObjectDisposedException

Non è possibile impostare questa proprietà perché il timer è stato eliminato.

ArgumentException

La Interval proprietà è stata impostata su un valore maggiore di Int32.MaxValue prima dell'abilitazione del timer.

Esempio

Nell'esempio seguente viene creata un'istanza di un Timer oggetto che genera l'evento Timer.Elapsed ogni due secondi (2000 millisecondi), imposta un gestore eventi per l'evento e avvia il timer. Il gestore eventi visualizza il valore della ElapsedEventArgs.SignalTime proprietà ogni volta che viene generato.

using namespace System;
using namespace System::Timers;

public ref class Example
{
private:
    static System::Timers::Timer^ aTimer;

public:
    static void Demo()
    {
        // Create a timer and set a two second interval.
        aTimer = gcnew System::Timers::Timer();
        aTimer->Interval = 2000;

        // Hook up the Elapsed event for the timer. 
        aTimer->Elapsed += gcnew System::Timers::ElapsedEventHandler(Example::OnTimedEvent);

        // Have the timer fire repeated events (true is the default)
        aTimer->AutoReset = true;

        // Start the timer
        aTimer->Enabled = true;

        Console::WriteLine("Press the Enter key to exit the program at any time... ");
        Console::ReadLine();
    }

private:
    static void OnTimedEvent(Object^ source, System::Timers::ElapsedEventArgs^ e)
    {
        Console::WriteLine("The Elapsed event was raised at {0}", e->SignalTime);
    }
};

int main()
{
    Example::Demo();
}
// The example displays output like the following: 
//       Press the Enter key to exit the program at any time... 
//       The Elapsed event was raised at 5/20/2015 8:48:58 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:00 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:02 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:04 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:06 PM

using System;
using System.Timers;

public class Example
{
    private static Timer aTimer;

    public static void Main()
    {
        // Create a timer and set a two second interval.
        aTimer = new System.Timers.Timer();
        aTimer.Interval = 2000;

        // Hook up the Elapsed event for the timer. 
        aTimer.Elapsed += OnTimedEvent;

        // Have the timer fire repeated events (true is the default)
        aTimer.AutoReset = true;

        // Start the timer
        aTimer.Enabled = true;

        Console.WriteLine("Press the Enter key to exit the program at any time... ");
        Console.ReadLine();
    }

    private static void OnTimedEvent(Object source, System.Timers.ElapsedEventArgs e)
    {
        Console.WriteLine("The Elapsed event was raised at {0}", e.SignalTime);
    }
}
// The example displays output like the following: 
//       Press the Enter key to exit the program at any time... 
//       The Elapsed event was raised at 5/20/2015 8:48:58 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:00 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:02 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:04 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:06 PM

open System.Timers

let onTimedEvent source (e: ElapsedEventArgs) =
    printfn $"The Elapsed event was raised at {e.SignalTime}"

// Create a timer and set a two second interval.
let aTimer = new Timer()
aTimer.Interval <- 2000

// Hook up the Elapsed event for the timer. 
aTimer.Elapsed.AddHandler onTimedEvent

// Have the timer fire repeated events (true is the default)
aTimer.AutoReset <- true

// Start the timer
aTimer.Enabled <- true

printfn "Press the Enter key to exit the program at any time... "
stdin.ReadLine() |> ignore

// The example displays output like the following: 
//       Press the Enter key to exit the program at any time... 
//       The Elapsed event was raised at 5/20/2015 8:48:58 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:00 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:02 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:04 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:06 PM

Imports System.Timers

Public Module Example
    Private aTimer As Timer

    Public Sub Main()
        ' Create a timer and set a two second interval.
        aTimer = New System.Timers.Timer()
        aTimer.Interval = 2000

        ' Hook up the Elapsed event for the timer.  
        AddHandler aTimer.Elapsed, AddressOf OnTimedEvent

        ' Have the timer fire repeated events (true is the default)
        aTimer.AutoReset = True

        ' Start the timer
        aTimer.Enabled = True

        Console.WriteLine("Press the Enter key to exit the program at any time... ")
        Console.ReadLine()
    End Sub

    Private Sub OnTimedEvent(source As Object, e As System.Timers.ElapsedEventArgs)
        Console.WriteLine("The Elapsed event was raised at {0}", e.SignalTime)
    End Sub
End Module
' The example displays output like the following: 
'       Press the Enter key to exit the program at any time... 
'       The Elapsed event was raised at 5/20/2015 8:48:58 PM 
'       The Elapsed event was raised at 5/20/2015 8:49:00 PM 
'       The Elapsed event was raised at 5/20/2015 8:49:02 PM 
'       The Elapsed event was raised at 5/20/2015 8:49:04 PM 
'       The Elapsed event was raised at 5/20/2015 8:49:06 PM

Commenti

L'impostazione Enabled su equivale a true chiamare Start, mentre l'impostazione Enabled su equivale a false chiamare Stop.

Nota

Il segnale per generare l'evento viene sempre accodato per l'esecuzione Elapsed in un ThreadPool thread. Ciò potrebbe comportare la generazione dell'evento Elapsed dopo che la Enabled proprietà è impostata su false. L'esempio di codice per il Stop metodo mostra un modo per aggirare questa race condition.

Se Enabled è impostato su true e AutoReset è impostato su false, Timer genera l'evento Elapsed una sola volta, la prima volta che l'intervallo è trascorso.

Se l'intervallo viene impostato dopo l'avvio Timer di , il conteggio viene reimpostato. Ad esempio, se si imposta l'intervallo su 5 secondi e quindi si imposta la Enabled proprietà truesu , il conteggio inizia al momento Enabled dell'impostazione. Se si reimposta l'intervallo su 10 secondi quando count è di 3 secondi, l'evento Elapsed viene generato per la prima volta 13 secondi dopo Enabled che è stato impostato su true.

Nota

Alcune finestre di progettazione visiva, ad esempio quelle in Microsoft Visual Studio, impostano la Enabled proprietà su true quando si inserisce un nuovo Timeroggetto .

Vedi anche

• Interval
• AutoReset
• Start()
• Stop()
• Elapsed