Timer Constructor (TimerCallback, Object, Int64, Int64)


Initializes a new instance of the Timer class, using 64-bit signed integers to measure time intervals.

Namespace:   System.Threading
Assembly:  mscorlib (in mscorlib.dll)

public Timer(
	TimerCallback callback,
	object state,
	long dueTime,
	long period


Type: System.Threading.TimerCallback

A TimerCallback delegate representing a method to be executed.

Type: System.Object

An object containing information to be used by the callback method, or null.

Type: System.Int64

The amount of time to delay before callback is invoked, in milliseconds. Specify Timeout.Infinite to prevent the timer from starting. Specify zero (0) to start the timer immediately.

Type: System.Int64

The time interval between invocations of callback, in milliseconds. Specify Timeout.Infinite to disable periodic signaling.

Exception Condition

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


The dueTime or period parameter is greater than 4294967294.

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.

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.

.NET Framework
Available since 1.1
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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