Type: System.Threading.Timer

System.Threading.Timer Class

Assembly: Mscorlib.dll
Namespace: System.Threading

Summary: Provides a mechanism for executing methods at specified intervals. This class cannot be inherited.

C# Syntax:


        public sealed class Timer : MarshalByRefObject, IDisposable

Remarks

Use a TimerCallback delegate to specify the methods associated with a Timer. The methods do not execute in the thread that created the timer; they execute in a separate thread that is automatically allocated by the system. The timer delegate is specified when the timer is constructed, and cannot be changed.

When creating a timer, the application specifies an amount of time to wait before the first invocation of the delegate methods (due time), and an amount of time to wait between subsequent invocations (period). A timer invokes its methods when its due time elapses, and invokes its methods once per period thereafter. You can change these values, or you can disable the timer, by using the Timer.Change method.

When a timer is no longer needed, use the Timer.Dispose method to free the resources held by the timer.

Example

The following example demonstrates the features of the Timer class.

using System;
using System.Threading;

class TimerExampleState 
{
   public int counter = 0;
   public Timer tmr;
}

class App 
{
   public static void Main()
   {
   TimerExampleState s = new TimerExampleState();

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

   // Create a timer that waits one second, then invokes every second.
   Timer timer = new Timer(timerDelegate, s,1000, 1000);
    
   // Keep a handle to the timer, so it can be disposed.
   s.tmr = timer;

   // The main thread does nothing until the timer is disposed.
   while(s.tmr != null)
         Thread.Sleep(0);
   Console.WriteLine("Timer example done.");
   }
   // The following method is called by the timer's delegate.

   static void CheckStatus(Object state)
   {
   TimerExampleState s =(TimerExampleState)state;
   s.counter++;
   Console.WriteLine("{0} Checking Status {1}.",DateTime.Now.TimeOfDay, s.counter);
   if(s.counter == 5)
      {
      // Shorten the period. Wait 10 seconds to restart the timer.
      (s.tmr).Change(10000,100);
      Console.WriteLine("changed...");
      }
   if(s.counter == 10)
      {
      Console.WriteLine("disposing of timer...");
      s.tmr.Dispose();
      s.tmr = null;
      }
   }
}

This code produces the following output (the exact timings returned will vary):

          				08:02:09.4811456 Checking Status 1. 
          				08:02:10.4825856 Checking Status 2. 
          				08:02:11.4840256 Checking Status 3. 
          				08:02:12.4854656 Checking Status 4. 
          				08:02:13.4869056 Checking Status 5. 
          				changed... 
          				08:02:23.4912912 Checking Status 6. 
          				08:02:23.5914352 Checking Status 7. 
          				08:02:23.6915792 Checking Status 8. 
          				08:02:23.7917232 Checking Status 9. 
          				08:02:23.8918672 Checking Status 10. 
          				disposing of timer... 
          				Timer example done.

System.Threading.Timer Member List:

Public Constructors

ctor #1	Overloaded: `.ctor(TimerCallback callback, object state, int dueTime, int period)` Initializes a new instance of the Timer class, using 32-bit signed integers to measure time intervals.
ctor #2	Overloaded: `.ctor(TimerCallback callback, object state, long dueTime, long period)` Initializes a new instance of the Timer class, using 64-bit signed integers to measure time intervals.
ctor #3	Overloaded: `.ctor(TimerCallback callback, object state, TimeSpan dueTime, TimeSpan period)` Initializes a new instance of the Timer class, using TimeSpan values to measure time intervals.
ctor #4	Overloaded: `.ctor(TimerCallback callback, object state, uint dueTime, uint period)` Initializes a new instance of the Timer class, using 32-bit unsigned integers to measure time intervals.

Public Methods

Change	Overloaded: `Change(int dueTime, int period)` Changes the start time and the interval between method invocations for a timer, using 32-bit signed integers to measure time intervals.
Change	Overloaded: `Change(long dueTime, long period)` Changes the start time and the interval between method invocations for a timer, using 64-bit signed integers to measure time intervals.
Change	Overloaded: `Change(TimeSpan dueTime, TimeSpan period)` Changes the start time and the interval between method invocations for a timer, using TimeSpan values to measure time intervals.
Change	Overloaded: `Change(uint dueTime, uint period)` Changes the start time and the interval between method invocations for a timer, using 32-bit unsigned integers to measure time intervals.
CreateObjRef (inherited from System.MarshalByRefObject)	See base class member description: System.MarshalByRefObject.CreateObjRef Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object.
Dispose	Overloaded: `Dispose()` Releases all resources used by the current instance of Timer.
Dispose	Overloaded: `Dispose(WaitHandle notifyObject)` Releases all resources used by the current instance of Timer and signals when the timer has been disposed of.
Equals (inherited from System.Object)	See base class member description: System.Object.Equals Derived from System.Object, the primary base class for all objects.
GetHashCode (inherited from System.Object)	See base class member description: System.Object.GetHashCode Derived from System.Object, the primary base class for all objects.
GetLifetimeService (inherited from System.MarshalByRefObject)	See base class member description: System.MarshalByRefObject.GetLifetimeService Retrieves the current lifetime service object that controls the lifetime policy for this instance.
GetType (inherited from System.Object)	See base class member description: System.Object.GetType Derived from System.Object, the primary base class for all objects.
InitializeLifetimeService (inherited from System.MarshalByRefObject)	See base class member description: System.MarshalByRefObject.InitializeLifetimeService Obtains a lifetime service object to control the lifetime policy for this instance.
ToString (inherited from System.Object)	See base class member description: System.Object.ToString Derived from System.Object, the primary base class for all objects.

Protected Methods

Finalize	Overridden: Releases the resources held by the current instance.
MemberwiseClone (inherited from System.Object)	See base class member description: System.Object.MemberwiseClone Derived from System.Object, the primary base class for all objects.

Hierarchy:

System.Object

System.MarshalByRefObject

System.Threading.Timer

System.Threading.Timer Member Details

Overloaded ctor #1

Summary: Initializes a new instance of the Timer class, using 32-bit signed integers to measure time intervals.

C# Syntax:


            public Timer(Timer(
   TimerCallback callback,
   object state,
   int dueTime,
   int period
);

Parameters:

callback

A TimerCallback delegate.

state

An object containing application-specific information relevant to the methods invoked by the callback parameter, or null.

dueTime

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

period

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

Exceptions

Exception Type	Condition
ArgumentOutOfRangeException	The dueTime or period parameter is negative and is not equal to Timeout.Infinite.
ArgumentNullException	The callback parameter is null.

Remarks

The callback parameter invokes its methods once after dueTime elapses, and then invokes its methods each time the period time interval elapses.

If dueTime is zero (0), callback performs its first invocation immediately. If dueTime is Timeout.Infinite, callback does not invoke its methods. The timer is disabled, but it can be re-enabled using the Timer.Change method.

If period is zero (0) or Timeout.Infinite and dueTime is not Infinite, callback invokes its methods once. The periodic behavior of the timer is disabled, but it can be re-enabled using the Change method.

Exception Type	Condition
ArgumentOutOfRangeException	The dueTime or period parameter is negative and is not equal to Timeout.Infinite.
NotSupportedException	The dueTime or period parameter is greater than 4294967294.

Exception Type	Condition
ArgumentOutOfRangeException	The number of milliseconds in the value of dueTime or period is negative and not equal to Timeout.Infinite, or is greater than Int32.MaxValue.
ArgumentNullException	The callback parameter is null.

Exception Type	Condition
ArgumentOutOfRangeException	The dueTime or period parameter is less than -1.
NotSupportedException	The dueTime or period parameter is greater than 4294967294.