Timer.Change Method

Reference

Definition

Namespace:: System.Threading

Assembly:: System.Threading.Timer.dll

Assembly:: System.Runtime.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Changes the start time and the interval between method invocations for a timer.

Overloads

Change(Int32, Int32)	Changes the start time and the interval between method invocations for a timer, using 32-bit signed integers to measure time intervals.
Change(Int64, Int64)	Changes the start time and the interval between method invocations for a timer, using 64-bit signed integers to measure time intervals.
Change(TimeSpan, TimeSpan)	Changes the start time and the interval between method invocations for a timer, using TimeSpan values to measure time intervals.
Change(UInt32, UInt32)	Changes the start time and the interval between method invocations for a timer, using 32-bit unsigned integers to measure time intervals.

Change(Int32, Int32)

Source:: Timer.cs

Source:: Timer.cs

Source:: Timer.cs

Changes the start time and the interval between method invocations for a timer, using 32-bit signed integers to measure time intervals.

public:
 bool Change(int dueTime, int period);

public bool Change (int dueTime, int period);

member this.Change : int * int -> bool

Public Function Change (dueTime As Integer, period As Integer) As Boolean

Parameters

dueTime: Int32

The amount of time to delay before the invoking the callback method specified when the Timer was constructed, in milliseconds. Specify Infinite to prevent the timer from restarting. Specify zero (0) to restart the timer immediately.

period: Int32

The time interval between invocations of the callback method specified when the Timer was constructed, in milliseconds. Specify Infinite to disable periodic signaling.

Returns

Boolean

true if the timer was successfully updated; otherwise, false.

Exceptions

ObjectDisposedException

The Timer has already been disposed.

ArgumentOutOfRangeException

The dueTime or period parameter is negative and is not equal to Infinite.

Examples

The following code example demonstrates how to start a Timer and, after a set number of invocations, change its period.

using namespace System;
using namespace System::Threading;

ref class StatusChecker
{
private:
    int invokeCount, maxCount;

public:
    StatusChecker(int count)
    {
        invokeCount  = 0;
        maxCount = count;
    }

    // This method is called by the timer delegate.
    void CheckStatus(Object^ stateInfo)
    {
        AutoResetEvent^ autoEvent = dynamic_cast<AutoResetEvent^>(stateInfo);
        Console::WriteLine("{0:h:mm:ss.fff} Checking status {1,2}.",
                           DateTime::Now, ++invokeCount);

        if (invokeCount == maxCount) {
            // Reset the counter and signal the waiting thread.
            invokeCount  = 0;
            autoEvent->Set();
        }
    }
};

ref class TimerExample
{
public:
    static void Main()
    {
        // Create an AutoResetEvent to signal the timeout threshold in the
        // timer callback has been reached.
        AutoResetEvent^ autoEvent = gcnew AutoResetEvent(false);

        StatusChecker^ statusChecker = gcnew StatusChecker(10);

        // Create a delegate that invokes methods for the timer.
        TimerCallback^ tcb =
           gcnew TimerCallback(statusChecker, &StatusChecker::CheckStatus);

        // Create a timer that invokes CheckStatus after one second, 
        // and every 1/4 second thereafter.
        Console::WriteLine("{0:h:mm:ss.fff} Creating timer.\n",
                           DateTime::Now);
        Timer^ stateTimer = gcnew Timer(tcb, autoEvent, 1000, 250);

        // When autoEvent signals, change the period to every half second.
        autoEvent->WaitOne(5000, false);
        stateTimer->Change(0, 500);
        Console::WriteLine("\nChanging period to .5 seconds.\n");

        // When autoEvent signals the second time, dispose of the timer.
        autoEvent->WaitOne(5000, false);
        stateTimer->~Timer();
        Console::WriteLine("\nDestroying timer.");
    }
};

int main()
{
    TimerExample::Main();
}
// The example displays output like the following:
//       11:59:54.202 Creating timer.
//       
//       11:59:55.217 Checking status  1.
//       11:59:55.466 Checking status  2.
//       11:59:55.716 Checking status  3.
//       11:59:55.968 Checking status  4.
//       11:59:56.218 Checking status  5.
//       11:59:56.470 Checking status  6.
//       11:59:56.722 Checking status  7.
//       11:59:56.972 Checking status  8.
//       11:59:57.223 Checking status  9.
//       11:59:57.473 Checking status 10.
//       
//       Changing period to .5 seconds.
//       
//       11:59:57.474 Checking status  1.
//       11:59:57.976 Checking status  2.
//       11:59:58.476 Checking status  3.
//       11:59:58.977 Checking status  4.
//       11:59:59.477 Checking status  5.
//       11:59:59.977 Checking status  6.
//       12:00:00.478 Checking status  7.
//       12:00:00.980 Checking status  8.
//       12:00:01.481 Checking status  9.
//       12:00:01.981 Checking status 10.
//       
//       Destroying timer.

using System;
using System.Threading;

class TimerExample
{
    static void Main()
    {
        // Create an AutoResetEvent to signal the timeout threshold in the
        // timer callback has been reached.
        var autoEvent = new AutoResetEvent(false);
        
        var statusChecker = new StatusChecker(10);

        // Create a timer that invokes CheckStatus after one second, 
        // and every 1/4 second thereafter.
        Console.WriteLine("{0:h:mm:ss.fff} Creating timer.\n", 
                          DateTime.Now);
        var stateTimer = new Timer(statusChecker.CheckStatus, 
                                   autoEvent, 1000, 250);

        // When autoEvent signals, change the period to every half second.
        autoEvent.WaitOne();
        stateTimer.Change(0, 500);
        Console.WriteLine("\nChanging period to .5 seconds.\n");

        // When autoEvent signals the second time, dispose of the timer.
        autoEvent.WaitOne();
        stateTimer.Dispose();
        Console.WriteLine("\nDestroying timer.");
    }
}

class StatusChecker
{
    private int invokeCount;
    private int  maxCount;

    public StatusChecker(int count)
    {
        invokeCount  = 0;
        maxCount = count;
    }

    // This method is called by the timer delegate.
    public void CheckStatus(Object stateInfo)
    {
        AutoResetEvent autoEvent = (AutoResetEvent)stateInfo;
        Console.WriteLine("{0} Checking status {1,2}.", 
            DateTime.Now.ToString("h:mm:ss.fff"), 
            (++invokeCount).ToString());

        if(invokeCount == maxCount)
        {
            // Reset the counter and signal the waiting thread.
            invokeCount = 0;
            autoEvent.Set();
        }
    }
}
// The example displays output like the following:
//       11:59:54.202 Creating timer.
//       
//       11:59:55.217 Checking status  1.
//       11:59:55.466 Checking status  2.
//       11:59:55.716 Checking status  3.
//       11:59:55.968 Checking status  4.
//       11:59:56.218 Checking status  5.
//       11:59:56.470 Checking status  6.
//       11:59:56.722 Checking status  7.
//       11:59:56.972 Checking status  8.
//       11:59:57.223 Checking status  9.
//       11:59:57.473 Checking status 10.
//       
//       Changing period to .5 seconds.
//       
//       11:59:57.474 Checking status  1.
//       11:59:57.976 Checking status  2.
//       11:59:58.476 Checking status  3.
//       11:59:58.977 Checking status  4.
//       11:59:59.477 Checking status  5.
//       11:59:59.977 Checking status  6.
//       12:00:00.478 Checking status  7.
//       12:00:00.980 Checking status  8.
//       12:00:01.481 Checking status  9.
//       12:00:01.981 Checking status 10.
//       
//       Destroying timer.

Imports System.Threading

Public Module Example
    Public Sub Main()
        ' Use an AutoResetEvent to signal the timeout threshold in the
        ' timer callback has been reached.
        Dim autoEvent As New AutoResetEvent(False)

        Dim statusChecker As New StatusChecker(10)

        ' Create a timer that invokes CheckStatus after one second, 
        ' and every 1/4 second thereafter.
        Console.WriteLine("{0:h:mm:ss.fff} Creating timer." & vbCrLf, 
                          DateTime.Now)
        Dim stateTimer As New Timer(AddressOf statusChecker.CheckStatus, 
                                    autoEvent, 1000, 250)

        ' When autoEvent signals, change the period to every half second.
        autoEvent.WaitOne()
        stateTimer.Change(0, 500)
        Console.WriteLine(vbCrLf & "Changing period to .5 seconds." & vbCrLf)

        ' When autoEvent signals the second time, dispose of the timer.
        autoEvent.WaitOne()
        stateTimer.Dispose()
        Console.WriteLine(vbCrLf & "Destroying timer.")
    End Sub
End Module

Public Class StatusChecker
    Dim invokeCount, maxCount As Integer 

    Sub New(count As Integer)
        invokeCount  = 0
        maxCount = count
    End Sub

    ' The timer callback method.
    Sub CheckStatus(stateInfo As Object)
        Dim autoEvent As AutoResetEvent = DirectCast(stateInfo, AutoResetEvent)
        invokeCount += 1
        Console.WriteLine("{0:h:mm:ss.fff} Checking status {1,2}.", 
                          DateTime.Now, invokeCount)
        If invokeCount = maxCount Then
            ' Reset the counter and signal the waiting thread.
            invokeCount = 0
            autoEvent.Set()
        End If
    End Sub
End Class
' The example displays output like the following:
'       11:59:54.202 Creating timer.
'       
'       11:59:55.217 Checking status  1.
'       11:59:55.466 Checking status  2.
'       11:59:55.716 Checking status  3.
'       11:59:55.968 Checking status  4.
'       11:59:56.218 Checking status  5.
'       11:59:56.470 Checking status  6.
'       11:59:56.722 Checking status  7.
'       11:59:56.972 Checking status  8.
'       11:59:57.223 Checking status  9.
'       11:59:57.473 Checking status 10.
'       
'       Changing period to .5 seconds.
'       
'       11:59:57.474 Checking status  1.
'       11:59:57.976 Checking status  2.
'       11:59:58.476 Checking status  3.
'       11:59:58.977 Checking status  4.
'       11:59:59.477 Checking status  5.
'       11:59:59.977 Checking status  6.
'       12:00:00.478 Checking status  7.
'       12:00:00.980 Checking status  8.
'       12:00:01.481 Checking status  9.
'       12:00:01.981 Checking status 10.
'       
'       Destroying timer.

Remarks

The callback method is invoked once after dueTime elapses, and thereafter each time the time interval specified by period elapses.

If dueTime is zero (0), the callback method is invoked immediately. If dueTime is Timeout.Infinite, the callback method is never invoked; the timer is disabled, but can be re-enabled by calling Change and specifying a positive value for dueTime.

If period is zero (0) or Timeout.Infinite, and dueTime is not Timeout.Infinite, the callback method is invoked once; the periodic behavior of the timer is disabled, but can be re-enabled by calling Change and specifying a positive value for period.

The Change method can be called from the TimerCallback delegate.

Applies to

Change(Int64, Int64)

Source:: Timer.cs

Source:: Timer.cs

Source:: Timer.cs

Changes the start time and the interval between method invocations for a timer, using 64-bit signed integers to measure time intervals.

public:
 bool Change(long dueTime, long period);

public bool Change (long dueTime, long period);

member this.Change : int64 * int64 -> bool

Public Function Change (dueTime As Long, period As Long) As Boolean

Parameters

dueTime: Int64

period: Int64

The time interval between invocations of the callback method specified when the Timer was constructed, in milliseconds. Specify Infinite to disable periodic signaling.

Returns

Boolean

true if the timer was successfully updated; otherwise, false.

Exceptions

ObjectDisposedException

The Timer has already been disposed.

ArgumentOutOfRangeException

dueTime or period is less than -1.

-or-

dueTime or period is greater than 4294967294.

Remarks

The callback method is invoked once after dueTime elapses, and thereafter each time the time interval specified by period elapses.

The Change method can be called from the TimerCallback delegate.

Applies to

Change(TimeSpan, TimeSpan)

Source:: Timer.cs

Source:: Timer.cs

Source:: Timer.cs

Changes the start time and the interval between method invocations for a timer, using TimeSpan values to measure time intervals.

public:
 bool Change(TimeSpan dueTime, TimeSpan period);

public:
 virtual bool Change(TimeSpan dueTime, TimeSpan period);

public bool Change (TimeSpan dueTime, TimeSpan period);

member this.Change : TimeSpan * TimeSpan -> bool

abstract member Change : TimeSpan * TimeSpan -> bool
override this.Change : TimeSpan * TimeSpan -> bool

Public Function Change (dueTime As TimeSpan, period As TimeSpan) As Boolean

Parameters

dueTime: TimeSpan

A TimeSpan representing the amount of time to delay before invoking the callback method specified when the Timer was constructed. Specify InfiniteTimeSpan to prevent the timer from restarting. Specify Zero to restart the timer immediately.

period: TimeSpan

The time interval between invocations of the callback method specified when the Timer was constructed. Specify InfiniteTimeSpan to disable periodic signaling.

Returns

Boolean

true if the timer was successfully updated; otherwise, false.

Implements

Change(TimeSpan, TimeSpan)

Exceptions

ObjectDisposedException

The Timer has already been disposed.

ArgumentOutOfRangeException

The dueTime or period parameter, in milliseconds, is less than -1.

NotSupportedException

The dueTime or period parameter, in milliseconds, is greater than 4294967294.

Examples

The following code example demonstrates how to start a Timer and, after a set number of invocations, change its period.

using namespace System;
using namespace System::Threading;
ref class StatusChecker
{
private:
   int invokeCount;
   int maxCount;

public:
   StatusChecker( int count )
      : invokeCount( 0 ), maxCount( count )
   {}


   // This method is called by the timer delegate.
   void CheckStatus( Object^ stateInfo )
   {
      AutoResetEvent^ autoEvent = dynamic_cast<AutoResetEvent^>(stateInfo);
      Console::WriteLine( "{0} Checking status {1,2}.", DateTime::Now.ToString(  "h:mm:ss.fff" ), (++invokeCount).ToString() );
      if ( invokeCount == maxCount )
      {
         
         // Reset the counter and signal main.
         invokeCount = 0;
         autoEvent->Set();
      }
   }

};

int main()
{
   AutoResetEvent^ autoEvent = gcnew AutoResetEvent( false );
   StatusChecker^ statusChecker = gcnew StatusChecker( 10 );
   
   // Create the delegate that invokes methods for the timer.
   TimerCallback^ timerDelegate = gcnew TimerCallback( statusChecker, &StatusChecker::CheckStatus );
   TimeSpan delayTime = TimeSpan(0,0,1);
   TimeSpan intervalTime = TimeSpan(0,0,0,0,250);
   
   // Create a timer that signals the delegate to invoke CheckStatus 
   // after one second, and every 1/4 second thereafter.
   Console::WriteLine( "{0} Creating timer.\n", DateTime::Now.ToString(  "h:mm:ss.fff" ) );
   Timer^ stateTimer = gcnew Timer( timerDelegate,autoEvent,delayTime,intervalTime );
   
   // When autoEvent signals, change the period to every 1/2 second.
   autoEvent->WaitOne( 5000, false );
   stateTimer->Change( TimeSpan(0), intervalTime + intervalTime );
   Console::WriteLine( "\nChanging period.\n" );
   
   // When autoEvent signals the second time, dispose of the timer.
   autoEvent->WaitOne( 5000, false );
   stateTimer->~Timer();
   Console::WriteLine( "\nDestroying timer." );
}

using System;
using System.Threading;

class TimerExample
{
    static void Main()
    {
        AutoResetEvent autoEvent     = new AutoResetEvent(false);
        StatusChecker  statusChecker = new StatusChecker(10);

        // Create the delegate that invokes methods for the timer.
        TimerCallback timerDelegate = 
            new TimerCallback(statusChecker.CheckStatus);

        TimeSpan delayTime = new TimeSpan(0, 0, 1);
        TimeSpan intervalTime = new TimeSpan(0, 0, 0, 0, 250);

        // Create a timer that signals the delegate to invoke 
        // CheckStatus after one second, and every 1/4 second 
        // thereafter.
        Console.WriteLine("{0} Creating timer.\n", 
            DateTime.Now.ToString("h:mm:ss.fff"));
        Timer stateTimer = new Timer(
            timerDelegate, autoEvent, delayTime, intervalTime);

        // When autoEvent signals, change the period to every 
        // 1/2 second.
        autoEvent.WaitOne(5000, false);
        stateTimer.Change(new TimeSpan(0), 
            intervalTime + intervalTime);
        Console.WriteLine("\nChanging period.\n");

        // When autoEvent signals the second time, dispose of 
        // the timer.
        autoEvent.WaitOne(5000, false);
        stateTimer.Dispose();
        Console.WriteLine("\nDestroying timer.");
    }
}

class StatusChecker
{
    int invokeCount, maxCount;

    public StatusChecker(int count)
    {
        invokeCount  = 0;
        maxCount = count;
    }

    // This method is called by the timer delegate.
    public void CheckStatus(Object stateInfo)
    {
        AutoResetEvent autoEvent = (AutoResetEvent)stateInfo;
        Console.WriteLine("{0} Checking status {1,2}.", 
            DateTime.Now.ToString("h:mm:ss.fff"), 
            (++invokeCount).ToString());

        if(invokeCount == maxCount)
        {
            // Reset the counter and signal Main.
            invokeCount  = 0;
            autoEvent.Set();
        }
    }
}

Imports System.Threading

Public Class TimerExample

    <MTAThread> _
    Shared Sub Main()
    
        Dim autoEvent As New AutoResetEvent(False)
        Dim statusChecker As New StatusChecker(10)

        ' Create the delegate that invokes methods for the timer.
        Dim timerDelegate As TimerCallback = _
            AddressOf statusChecker.CheckStatus

        Dim delayTime As New TimeSpan(0, 0, 1)
        Dim intervalTime As New TimeSpan(0, 0, 0, 0, 250)

        ' Create a timer that signals the delegate to invoke 
        ' CheckStatus after one second, and every 1/4 second 
        ' thereafter.
        Console.WriteLine("{0} Creating timer." & vbCrLf, _
            DateTime.Now.ToString("h:mm:ss.fff"))
        Dim stateTimer As Timer = New Timer( _
            timerDelegate, autoEvent, delayTime, intervalTime)

        ' When autoEvent signals, change the period to every 
        ' 1/2 second.
        autoEvent.WaitOne(5000, False)
        stateTimer.Change( _
            new TimeSpan(0), intervalTime.Add(intervalTime))
        Console.WriteLine(vbCrLf & "Changing period." & vbCrLf)

        ' When autoEvent signals the second time, dispose of 
        ' the timer.
        autoEvent.WaitOne(5000, False)
        stateTimer.Dispose()
        Console.WriteLine(vbCrLf & "Destroying timer.")
    
    End Sub
End Class

Public Class StatusChecker

    Dim invokeCount, maxCount As Integer 

    Sub New(count As Integer)
        invokeCount  = 0
        maxCount = count
    End Sub

    ' This method is called by the timer delegate.
    Sub CheckStatus(stateInfo As Object)
        Dim autoEvent As AutoResetEvent = _
            DirectCast(stateInfo, AutoResetEvent)
        invokeCount += 1
        Console.WriteLine("{0} Checking status {1,2}.", _
            DateTime.Now.ToString("h:mm:ss.fff"), _
            invokeCount.ToString())

        If invokeCount = maxCount Then
        
            ' Reset the counter and signal to stop the timer.
            invokeCount  = 0
            autoEvent.Set()
        End If
    End Sub

End Class

Remarks

The callback method is invoked once after dueTime elapses, and thereafter each time the time interval specified by period elapses.

If dueTime is TimeSpan.Zero, the callback method is invoked immediately. If dueTime is InfiniteTimeSpan, the callback method is never invoked; the timer is disabled, but can be re-enabled by calling Change and specifying a positive value for dueTime.

If period is TimeSpan.Zero or InfiniteTimeSpan, and dueTime is positive, the callback method is invoked once; the periodic behavior of the timer is disabled, but can be re-enabled by calling Change and specifying a value greater than zero for period.

The Change method can be called from the TimerCallback delegate.

Applies to

Change(UInt32, UInt32)

Source:: Timer.cs

Source:: Timer.cs

Source:: Timer.cs

Important

This API is not CLS-compliant.

Changes the start time and the interval between method invocations for a timer, using 32-bit unsigned integers to measure time intervals.

public:
 bool Change(System::UInt32 dueTime, System::UInt32 period);

[System.CLSCompliant(false)]
public bool Change (uint dueTime, uint period);

[<System.CLSCompliant(false)>]
member this.Change : uint32 * uint32 -> bool

Public Function Change (dueTime As UInteger, period As UInteger) As Boolean

Parameters

dueTime: UInt32

period: UInt32

The time interval between invocations of the callback method specified when the Timer was constructed, in milliseconds. Specify Infinite to disable periodic signaling.

Returns

Boolean

true if the timer was successfully updated; otherwise, false.

Attributes: CLSCompliantAttribute

Exceptions

ObjectDisposedException

The Timer has already been disposed.

Remarks

The callback method is invoked once after dueTime elapses, and thereafter each time the time interval specified by period elapses.

The Change method can be called from the TimerCallback delegate.

Applies to

Del via

Timer.Change Method

Definition

Overloads

Change(Int32, Int32)

Parameters

Returns

Exceptions

Examples

Remarks

See also

Applies to

Change(Int64, Int64)

Parameters

Returns

Exceptions

Remarks

See also

Applies to

Change(TimeSpan, TimeSpan)

Parameters

Returns

Implements

Exceptions

Examples

Remarks

See also

Applies to

Change(UInt32, UInt32)

Parameters

Returns

Exceptions

Remarks

See also

Applies to

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