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Timer.Change Method (TimeSpan, TimeSpan)

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

Namespace:  System.Threading
Assembly:  mscorlib (in mscorlib.dll)
public bool Change(
	TimeSpan dueTime,
	TimeSpan period
)

Parameters

dueTime
Type: System.TimeSpan

A TimeSpan representing the amount of time to delay before invoking the callback method specified when the Timer was constructed. Specify negative one (-1) milliseconds to prevent the timer from restarting. Specify zero (0) to restart the timer immediately.

period
Type: System.TimeSpan

The time interval between invocations of the callback method specified when the Timer was constructed. Specify negative one (-1) milliseconds to disable periodic signaling.

Return Value

Type: System.Boolean
true if the timer was successfully updated; otherwise, false.
ExceptionCondition
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.

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 negative one (-1) milliseconds, 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 negative one (-1) milliseconds, 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 following code example demonstrates how to start a Timer and, after a set number of invocations, change its period.

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();
        }
    }
}

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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