Timer Constructors
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.
Initializes a new instance of the Timer
class.
Timer(TimerCallback) |
Initializes a new instance of the Timer class with an infinite period and an infinite due time, using the newly created Timer object as the state object. |
Timer(TimerCallback, Object, Int32, Int32) |
Initializes a new instance of the |
Timer(TimerCallback, Object, Int64, Int64) |
Initializes a new instance of the |
Timer(TimerCallback, Object, TimeSpan, TimeSpan) |
Initializes a new instance of the |
Timer(TimerCallback, Object, UInt32, UInt32) |
Initializes a new instance of the |
- Source:
- Timer.cs
- Source:
- Timer.cs
- Source:
- Timer.cs
public:
Timer(System::Threading::TimerCallback ^ callback);
public Timer (System.Threading.TimerCallback callback);
new System.Threading.Timer : System.Threading.TimerCallback -> System.Threading.Timer
Public Sub New (callback As TimerCallback)
Parameters
- callback
- TimerCallback
A TimerCallback delegate representing a method to be executed.
Examples
The following code example creates a new timer, using the timer itself as the state object. The Change method is used to start the timer. When the timer callback occurs, the state object is used to turn the timer off.
using System;
using System.Threading;
public class Example
{
public static void Main()
{
// Create an instance of the Example class, and start two
// timers.
Example ex = new Example();
ex.StartTimer(2000);
ex.StartTimer(1000);
Console.WriteLine("Press Enter to end the program.");
Console.ReadLine();
}
public void StartTimer(int dueTime)
{
Timer t = new Timer(new TimerCallback(TimerProc));
t.Change(dueTime, 0);
}
private void TimerProc(object state)
{
// The state object is the Timer object.
Timer t = (Timer) state;
t.Dispose();
Console.WriteLine("The timer callback executes.");
}
}
Imports System.Threading
Public Class Example
Public Shared Sub Main()
' Create an instance of the Example class, and start two
' timers.
Dim ex As New Example()
ex.StartTimer(2000)
ex.StartTimer(1000)
Console.WriteLine("Press Enter to end the program.")
Console.ReadLine()
End Sub
Public Sub StartTimer(ByVal dueTime As Integer)
Dim t As New Timer(AddressOf TimerProc)
t.Change(dueTime, 0)
End Sub
Private Sub TimerProc(ByVal state As Object)
' The state object is the Timer object.
Dim t As Timer = CType(state, Timer)
t.Dispose()
Console.WriteLine("The timer callback executes.")
End Sub
End Class
Remarks
Call this constructor when you want to use the Timer object itself as the state object. After creating the timer, use the Change method to set the interval and due time.
This constructor specifies an infinite due time before the first callback and an infinite interval between callbacks, in order to prevent the first callback from occurring before the Timer object is assigned to the state object.
The method specified for callback
should be reentrant, because it is called on ThreadPool threads. The method can be executed simultaneously on two thread pool threads if the timer interval is less than the time required to execute the method, or if all thread pool threads are in use and the method is queued multiple times.
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 2.0, 2.1 |
- Source:
- Timer.cs
- Source:
- Timer.cs
- Source:
- Timer.cs
Initializes a new instance of the Timer
class, using a 32-bit signed integer to specify the time interval.
public:
Timer(System::Threading::TimerCallback ^ callback, System::Object ^ state, int dueTime, int period);
public Timer (System.Threading.TimerCallback callback, object state, int dueTime, int period);
public Timer (System.Threading.TimerCallback callback, object? state, int dueTime, int period);
new System.Threading.Timer : System.Threading.TimerCallback * obj * int * int -> System.Threading.Timer
Public Sub New (callback As TimerCallback, state As Object, dueTime As Integer, period As Integer)
Parameters
- callback
- TimerCallback
A TimerCallback delegate representing a method to be executed.
- state
- Object
An object containing information to be used by the callback method, or null
.
- dueTime
- Int32
The amount of time to delay before callback
is invoked, in milliseconds. Specify Infinite to prevent the timer from starting. Specify zero (0) to start the timer immediately.
- period
- Int32
The time interval between invocations of callback
, in milliseconds. Specify Infinite to disable periodic signaling.
Exceptions
The dueTime
or period
parameter is negative and is not equal to Infinite.
The callback
parameter is null
.
Examples
The following code example shows how to create a TimerCallback
delegate and initialize a new instance of the Timer
class.
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 delegate specified by the callback
parameter is invoked once after dueTime
elapses, and thereafter each time the period
time interval elapses.
If dueTime
is zero (0), callback
is invoked immediately. If dueTime
is Timeout.Infinite, callback
is not invoked; the timer is disabled, but can be re-enabled by calling the Change method.
Because the Timer class has the same resolution as the system clock, which is approximately 15 milliseconds on Windows 7 and Windows 8 systems, the callback
delegate executes at intervals defined by the resolution of the system clock if period
is less than the resolution of the system clock. If period
is zero (0) or Timeout.Infinite and dueTime
is not Timeout.Infinite, callback
is invoked once; the periodic behavior of the timer is disabled, but can be re-enabled using the Change method.
Note
The system clock that is used is the same clock used by GetTickCount, which is not affected by changes made with timeBeginPeriod and timeEndPeriod.
The method specified for callback
should be reentrant, because it is called on ThreadPool threads. The method can be executed simultaneously on two thread pool threads if the timer interval is less than the time required to execute the method, or if all thread pool threads are in use and the method is queued multiple times.
See also
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
UWP | 10.0 |
- Source:
- Timer.cs
- Source:
- Timer.cs
- Source:
- Timer.cs
Initializes a new instance of the Timer
class, using 64-bit signed integers to measure time intervals.
public:
Timer(System::Threading::TimerCallback ^ callback, System::Object ^ state, long dueTime, long period);
public Timer (System.Threading.TimerCallback callback, object? state, long dueTime, long period);
public Timer (System.Threading.TimerCallback callback, object state, long dueTime, long period);
new System.Threading.Timer : System.Threading.TimerCallback * obj * int64 * int64 -> System.Threading.Timer
Public Sub New (callback As TimerCallback, state As Object, dueTime As Long, period As Long)
Parameters
- callback
- TimerCallback
A TimerCallback delegate representing a method to be executed.
- state
- Object
An object containing information to be used by the callback method, or null
.
- dueTime
- Int64
The amount of time to delay before callback
is invoked, in milliseconds. Specify Infinite to prevent the timer from starting. Specify zero (0) to start the timer immediately.
- period
- Int64
The time interval between invocations of callback
, in milliseconds. Specify Infinite to disable periodic signaling.
Exceptions
The dueTime
or period
parameter is negative and is not equal to Infinite.
The dueTime
or period
parameter is greater than 4294967294.
Remarks
The delegate specified by the callback
parameter is invoked once after dueTime
elapses, and thereafter each time the period
time interval elapses.
If dueTime
is zero (0), callback
is invoked immediately. If dueTime
is Timeout.Infinite, callback
is not invoked; the timer is disabled, but can be re-enabled by calling the Change method.
Because the Timer class has the same resolution as the system clock, which is approximately 15 milliseconds on Windows 7 and Windows 8 systems, the callback
delegate executes at intervals defined by the resolution of the system clock if period
is less than the resolution of the system clock. If period
is zero (0) or Timeout.Infinite and dueTime
is not Timeout.Infinite, callback
is invoked once; the periodic behavior of the timer is disabled, but can be re-enabled using the Change method.
Note
The system clock that is used is the same clock used by GetTickCount, which is not affected by changes made with timeBeginPeriod and timeEndPeriod.
The method specified for callback
should be reentrant, because it is called on ThreadPool threads. The method can be executed simultaneously on two thread pool threads if the timer interval is less than the time required to execute the method, or if all thread pool threads are in use and the method is queued multiple times.
See also
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 2.0, 2.1 |
- Source:
- Timer.cs
- Source:
- Timer.cs
- Source:
- Timer.cs
Initializes a new instance of the Timer
class, using TimeSpan values to measure time intervals.
public:
Timer(System::Threading::TimerCallback ^ callback, System::Object ^ state, TimeSpan dueTime, TimeSpan period);
public Timer (System.Threading.TimerCallback callback, object state, TimeSpan dueTime, TimeSpan period);
public Timer (System.Threading.TimerCallback callback, object? state, TimeSpan dueTime, TimeSpan period);
new System.Threading.Timer : System.Threading.TimerCallback * obj * TimeSpan * TimeSpan -> System.Threading.Timer
Public Sub New (callback As TimerCallback, state As Object, dueTime As TimeSpan, period As TimeSpan)
Parameters
- callback
- TimerCallback
A delegate representing a method to be executed.
- state
- Object
An object containing information to be used by the callback method, or null
.
- dueTime
- TimeSpan
The amount of time to delay before the callback
is invoked. Specify InfiniteTimeSpan to prevent the timer from starting. Specify Zero to start the timer immediately.
- period
- TimeSpan
The time interval between invocations of callback
. Specify InfiniteTimeSpan to disable periodic signaling.
Exceptions
The number of milliseconds in the value of dueTime
or period
is negative and not equal to Infinite, or is greater than Int32.MaxValue.
The callback
parameter is null
.
Examples
The following code example shows how to create a TimerCallback
delegate and initialize a new instance of the Timer
class.
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 delegate specified by the callback
parameter is invoked once after dueTime
elapses, and thereafter each time the period
time interval elapses.
If dueTime
is zero (0), callback
is invoked immediately. If dueTime
is negative one (-1) milliseconds, callback
is not invoked; the timer is disabled, but can be re-enabled by calling the Change method.
Because the Timer class has the same resolution as the system clock, which is approximately 15 milliseconds on Windows 7 and Windows 8 systems, the callback
delegate executes at intervals defined by the resolution of the system clock if period
is less than the resolution of the system clock. If period
is zero (0) or negative one (-1) milliseconds and dueTime
is positive, callback
is invoked once; the periodic behavior of the timer is disabled, but can be re-enabled using the Change method.
Note
The system clock that is used is the same clock used by GetTickCount, which is not affected by changes made with timeBeginPeriod and timeEndPeriod.
The method specified for callback
should be reentrant, because it is called on ThreadPool threads. The method can be executed simultaneously on two thread pool threads if the timer interval is less than the time required to execute the method, or if all thread pool threads are in use and the method is queued multiple times.
See also
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
UWP | 10.0 |
- Source:
- Timer.cs
- Source:
- Timer.cs
- Source:
- Timer.cs
Important
This API is not CLS-compliant.
Initializes a new instance of the Timer
class, using 32-bit unsigned integers to measure time intervals.
public:
Timer(System::Threading::TimerCallback ^ callback, System::Object ^ state, System::UInt32 dueTime, System::UInt32 period);
[System.CLSCompliant(false)]
public Timer (System.Threading.TimerCallback callback, object? state, uint dueTime, uint period);
[System.CLSCompliant(false)]
public Timer (System.Threading.TimerCallback callback, object state, uint dueTime, uint period);
[<System.CLSCompliant(false)>]
new System.Threading.Timer : System.Threading.TimerCallback * obj * uint32 * uint32 -> System.Threading.Timer
Public Sub New (callback As TimerCallback, state As Object, dueTime As UInteger, period As UInteger)
Parameters
- callback
- TimerCallback
A delegate representing a method to be executed.
- state
- Object
An object containing information to be used by the callback method, or null
.
- dueTime
- UInt32
The amount of time to delay before callback
is invoked, in milliseconds. Specify Infinite to prevent the timer from starting. Specify zero (0) to start the timer immediately.
- period
- UInt32
The time interval between invocations of callback
, in milliseconds. Specify Infinite to disable periodic signaling.
- Attributes
Exceptions
The dueTime
or period
parameter is negative and is not equal to Infinite.
The callback
parameter is null
.
Remarks
The delegate specified by the callback
parameter is invoked once after dueTime
elapses, and thereafter each time the period
time interval elapses.
If dueTime
is zero (0), callback
is invoked immediately. If dueTime
is Timeout.Infinite, callback
is not invoked; the timer is disabled, but can be re-enabled by calling the Change method.
Because the Timer class has the same resolution as the system clock, which is approximately 15 milliseconds on Windows 7 and Windows 8 systems, the callback
delegate executes at intervals defined by the resolution of the system clock if period
is less than the resolution of the system clock. If period
is zero (0) or Timeout.Infinite and dueTime
is not Timeout.Infinite, callback
is invoked once; the periodic behavior of the timer is disabled, but can be re-enabled using the Change method.
Note
The system clock that is used is the same clock used by GetTickCount, which is not affected by changes made with timeBeginPeriod and timeEndPeriod.
The method specified for callback
should be reentrant, because it is called on ThreadPool threads. The method can be executed simultaneously on two thread pool threads if the timer interval is less than the time required to execute the method, or if all thread pool threads are in use and the method is queued multiple times.
See also
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 2.0, 2.1 |
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