I have a Console App and in the main method, I have code like this:
Timer time = new Timer(seconds * 1000); //to milliseconds
time.Enabled = true;
time.Elapsed += new ElapsedEventHandler(time_Elapsed);
I only want the timer to run once so my idea is that I should stop the timer in the time_Elapsed method. However, since my timer exists in Main(), I can't access it.
You have access to the Timer inside of the timer_Elapsed method:
public void timer_Elapsed(object sender, ElapsedEventArgs e)
{
Timer timer = (Timer)sender; // Get the timer that fired the event
timer.Stop(); // Stop the timer that fired the event
}
The above method will stop whatever Timer fired the Event (in case you have multiple Timers using the same handler and you want each Timer to have the same behavior).
You could also set the behavior when you instantiate the Timer:
var timer = new Timer();
timer.AutoReset = false; // Don't reset the timer after the first fire
A little example app:
static void Main(string[] args)
{
int seconds = 2;
Timer time = new Timer(seconds * 1000); //to milliseconds
time.Enabled = true;
time.Elapsed += new ElapsedEventHandler(MyHandler);
time.Start();
Console.ReadKey();
}
private static void MyHandler(object e, ElapsedEventArgs args)
{
var timer = (Timer) e;
timer.Stop();
}
I assume that you're using System.Timers.Timer rather than System.Windows.Forms.Timer?
You have two options.
First, as probably the best, is to set the AutoReset property to false. This should do exactly what you want.
time.AutoReset = false;
The other option is to call Stop in the event handler.
You may also use the System.Threading.Timer. Its constructor takes two time-related parameters:
The delay before the first "tick" (due time)
The period
Set the period to Timeout.Infinite to prevent from firing again.
Related
I have a System.Timers.Timer instance created in the main thread. Now I call timer.Stop() to try to terminate that time and want to wait until the timer is really terminated. How could I do that?
Is there any similar method like System.Threading.Thread.Join()?
Here are some codes
//the main thread:
var aTimer = New Timer();
aTimer.Elapsed += SomeTimerTask;
aTimer.AutoReset = True;
aTimer.Start();
//some other logic...
//stop that timer:
aTimer.Stop();
//now I need to wait until that timer is really stopped,
//but I cannot touch the method SomeTimerTask().
//so I need something like System.Threading.Thread.Join()...
You could make use of a ResetEvents which are wait handles which can block a thread until you set the state to signaled:
class TimerAndWait
{
private ManualResetEvent resetEvent = new ManualResetEvent(false);
public void DoWork()
{
var aTimer = new System.Timers.Timer(5000);
aTimer.Elapsed += SomeTimerTask;
aTimer.Elapsed += ATimer_Elapsed;
aTimer.AutoReset = true;
aTimer.Start();
// Do something else
resetEvent.WaitOne(); // This blocks the thread until resetEvent is set
resetEvent.Close();
aTimer.Stop();
}
private void ATimer_Elapsed(object sender, ElapsedEventArgs e)
{
resetEvent.Set();
}
}
If you want a async/task-based solution you have to use the ThreadPool.RegisterWaitForSingleObject method
The Timer does not fire up the Elapsed when you call stop as you can read in the docs of the Stop()-Method:
Stops raising the Elapsed event by setting Enabled to false.
The Elapsed-Event is only triggered when the Timers Enabled-Property is set to true and the given Interval (which you have to set) is elapsed (this can happen multiple times).
So if you stop your Timer before the Interval is elapsed, you might have to trigger your code in some other way.
I have included the System.Timers package, but when I type:
Timer.Elapsed; //its not working, the property elapsed is just not there.
I remember it was there in VB.NET. Why doesn't this work?
It's not a property. It's an event.
So you gotta provide an event handler that will execute every time the timer ticks. Something like this:
public void CreateTimer()
{
var timer = new System.Timers.Timer(1000); // fire every 1 second
timer.Elapsed += HandleTimerElapsed;
}
public void HandleTimerElapsed(object sender, ElapsedEventArgs e)
{
// do whatever it is that you need to do on a timer
}
Microsofts example.
http://msdn.microsoft.com/en-us/library/system.timers.timer.elapsed.aspx
Elapsed is an event and therefore requires an eventhandler.
using System;
using System.Timers;
public class Timer1
{
private static System.Timers.Timer aTimer;
public static void Main()
{
// Create a timer with a ten second interval.
aTimer = new System.Timers.Timer(10000);
// Hook up the Elapsed event for the timer.
aTimer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
// Set the Interval to 2 seconds (2000 milliseconds).
aTimer.Interval = 2000;
aTimer.Enabled = true;
Console.WriteLine("Press the Enter key to exit the program.");
Console.ReadLine();
}
// Specify what you want to happen when the Elapsed event is
// raised.
private static void OnTimedEvent(object source, ElapsedEventArgs e)
{
Console.WriteLine("The Elapsed event was raised at {0}", e.SignalTime);
}
}
/* This code example produces output similar to the following:
Press the Enter key to exit the program.
The Elapsed event was raised at 5/20/2007 8:42:27 PM
The Elapsed event was raised at 5/20/2007 8:42:29 PM
The Elapsed event was raised at 5/20/2007 8:42:31 PM
...
*/
The previous answers here are all correct, however with .net 6 / VS2022 now out and about nullability is big deal, and all the above answers will throw compiler warning CS8622.
The solution to this is to simply mark the source object as nullable in your callback function's parameters, like such:
...
var timer = new System.Timers.Timer(2000); // every 2000ms
timer.Elapsed += TimerElapsedHandler;
...
public void TimerElapsedHandler(object? source, ElapsedEventArgs e)
{
//Your Handling Code Here
}
You need an event handler, then after Enabling while assigning event handler and stop in your handler a condition
Timer = new System.Timers.Timer();
Timer.Elapsed += new System.Timers.ElapsedEventHandler(PageLoaded);
Timer.Interval = 3000;
Timer.Enabled = true;
...................
public void PageLoaded(object source, System.Timers.ElapsedEventArgs e)
{
// Do what ever here
if (StopCondition)Timer.Enabled = false;
}
This question already has answers here:
How do you add a timer to a C# console application
(12 answers)
Closed 3 years ago.
What is the best way to implement a timer? A code sample would be great! For this question, "best" is defined as most reliable (least number of misfires) and precise. If I specify an interval of 15 seconds, I want the target method invoked every 15 seconds, not every 10 - 20 seconds. On the other hand, I don't need nanosecond accuracy. In this example, it would be acceptable for the method to fire every 14.51 - 15.49 seconds.
Use the Timer class.
public static void Main()
{
System.Timers.Timer aTimer = new System.Timers.Timer();
aTimer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
aTimer.Interval = 5000;
aTimer.Enabled = true;
Console.WriteLine("Press \'q\' to quit the sample.");
while(Console.Read() != 'q');
}
// Specify what you want to happen when the Elapsed event is raised.
private static void OnTimedEvent(object source, ElapsedEventArgs e)
{
Console.WriteLine("Hello World!");
}
The Elapsed event will be raised every X amount of milliseconds, specified by the Interval property on the Timer object. It will call the Event Handler method you specify. In the example above, it is OnTimedEvent.
By using System.Windows.Forms.Timer class you can achieve what you need.
System.Windows.Forms.Timer t = new System.Windows.Forms.Timer();
t.Interval = 15000; // specify interval time as you want
t.Tick += new EventHandler(timer_Tick);
t.Start();
void timer_Tick(object sender, EventArgs e)
{
//Call method
}
By using stop() method you can stop timer.
t.Stop();
It's not clear what type of application you're going to develop (desktop, web, console...)
The general answer, if you're developing Windows.Forms application, is use of
System.Windows.Forms.Timer class. The benefit of this is that it runs on UI thread, so it's simple just define it, subscribe to its Tick event and run your code on every 15 second.
If you do something else then windows forms (it's not clear from the question), you can choose System.Timers.Timer, but this one runs on other thread, so if you are going to act on some UI elements from the its Elapsed event, you have to manage it with "invoking" access.
Reference ServiceBase to your class and put the below code in the OnStartevent:
Constants.TimeIntervalValue = 1 (hour)..Ideally you should set this value in config file.
StartSendingMails = function name you want to run in the application.
protected override void OnStart(string[] args)
{
// It tells in what interval the service will run each time.
Int32 timeInterval = Int32.Parse(Constants.TimeIntervalValue) * 60 * 60 * 1000;
base.OnStart(args);
TimerCallback timerDelegate = new TimerCallback(StartSendingMails);
serviceTimer = new Timer(timerDelegate, null, 0, Convert.ToInt32(timeInterval));
}
My timer 'Elapsed' event fires twice when the program is started. The only assignment of the 'Elapsed' event handler is in 'Main' method. Is there something that I'm doing wrong?
//class level clock
public static System.Timers.Timer Clock;
static void Main(string[] args)
{
Clock = new System.Timers.Timer();
Clock.Elapsed += new ElapsedEventHandler(Clock_Elapsed);
Clock.AutoReset = false;
Clock.Interval = timerInterval; //this needs to be in milliseconds!
Clock.Enabled = true;
//run infinite loop until q is pressed
while (Console.Read() != 'q')
{}
}
static void Clock_Elapsed(object sender, ElapsedEventArgs e)
{
Clock.Stop();
//do some stuff
Clock.Start();
}
UPDATE:
The AutoReset provided by #fparadis2 fixed the firing twice. The base issue was that my timer interval was set to 30 milliseconds instead of 30000 milliseconds(30 seconds) so that the event was double firing.
If timerInverval is small enough, it might be possible that the Elapsed event is fired twice before you get the chance to stop the clock. You should do
Clock.AutoReset = false;
in order to be notified only once each time you start the timer.
As specified in the Timer Class documentation:
If processing of the Elapsed event lasts longer than Interval, the event might be raised again on another ThreadPool thread. In this situation, the event handler should be reentrant.
You may also consider checking this pattern.
I would like to slow down a loop so that it loops every 5 seconds.
In ActionScript, I would use a timer and a timer complete event to do this. How would I go about it in C#?
You can add this call inside your loop:
System.Threading.Thread.Sleep(5000); // 5,000 ms
or preferable for better readability:
System.Threading.Thread.Sleep(TimeSpan.FromSeconds(5));
However, if your application has a user interface you should never sleep on the foreground thread (the thread that processes the applications message loop).
You can try using Timer,
using System;
public class PortChat
{
public static System.Timers.Timer _timer;
public static void Main()
{
_timer = new System.Timers.Timer();
_timer.Interval = 5000;
_timer.Elapsed += new System.Timers.ElapsedEventHandler(_timer_Elapsed);
_timer.Enabled = true;
Console.ReadKey();
}
static void _timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
//Do Your loop
}
}
Also if your operation in loop can last more then 5 sec, You can set
_timer.AutoReset = false;
to disable next timer tick until operation finish in loop
But then end end of loop You need again to enable timer like
_timer.Enabled = true;
Don't use a loop at all. Set up a Timer object and react to its fired event. Watch out, because these events will fire on a different thread (the timer's thread from the threadpool).
Let's say you have a for-loop that you want to use for writing to a database every second. I would then create a timer that is set to a 1000 ms interval and then use the timer the same way you would use a while-loop if you want it to act like a for-loop. By creating the integer before the loop and adding to it inside it.
public patial class Form1 : From
{
timer1.Start();
int i = 0;
int howeverLongYouWantTheLoopToLast = 10;
private void timer1_Tick(object sender, EventArgs e)
{
if (i < howeverLongYouWantTheLoopToLast)
{
writeQueryMethodThatIAssumeYouHave(APathMaybe, i); // <-- Just an example, write whatever you want to loop to do here.
i++;
}
else
{
timer1.Stop();
//Maybe add a little message here telling the user the write is done.
}
}
}