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Code should be executed one time after short delay

I have this Timer:
Timer delayTimer = new Timer();
delayTimer.Interval = 500;
delayTimer.Elapsed += (object sender, ElapsedEventArgs e) => {
Console.WriteLine("test");
textInputDialog.Show();
delayTimer.Stop();
};
delayTimer.Start();
Here I have the following problems:
Timer never stops. Code is executed every 500ms.
textInputDialog.Show(); doesn't work (perhaps cause of problem above)
What is wrong with my code?
Alternative solutions:
This is an alternative to timer as Jens Horstmann mentioned. And this is called on the UI thread:
private async Task SendWithDelay()
{
await Task.Delay(500);
textInputDialog.Show();
}
Another alternative would be NSTimer:
NSTimer.CreateScheduledTimer(new TimeSpan(0,0,0,0,500), delegate {
textInputDialog.Show();
});
And to invoke a call on the UI thread you can use InvokeOnMainThread:
Timer delayTimer = new Timer();
delayTimer.Interval = 500;
delayTimer.Elapsed += (object sender, ElapsedEventArgs e) => {
delayTimer.Stop();
Console.WriteLine("test");
InvokeOnMainThread (() => {
textInputDialog.Show();
});
};
delayTimer.Start();

Stop the timer before you show the dialog:
delayTimer.Elapsed += (object sender, ElapsedEventArgs e) => {
delayTimer.Stop();
Console.WriteLine("test");
textInputDialog.Show();
};
Also you probably used the wrong timer. Don't use System.Threading.Timer or System.Timers because this involves multithreading which does not work well with winforms or WPF. (This is probably the reason your MessageBox does not show - its called on the wrong thread)
In WPF you should use System.Windows.Threading.DispatcherTimer
Edit
In Winforms you should use System.Windows.Forms.Timer (see comments)

Here is a solution without async/await
It also happen to fit in a single statement, which is rather elegant.
This is a C#, cross-platform solution to perform an action after a delay.
Also works for a recurring task.
using System.Threading;
var delayTimer = new Timer((state) => // Create timer, forget about it
InvokeOnMainThread(() => // Fire on main thread
textInputDialog.Show() // Your code goes here
),
null, // Ignore the state
5 * 1000, // 5 seconds until the 1st fire
Timeout.Infinite); // Do not repeat

Something like this worked for me:
private async Task DelayedShow()
{
await Task.Delay(500);
await _loadPop.textInputDialog.Show();
}
Remember to call the method like this:
BeginInvokeOnMainThread(() => DelayedShow());

Alternative to Thread.Sleep that block

I am looking for an alternative to calling Thread.Sleep which does not block the thread but instead returns the thread back into the thread pool. Does such a thing exist?

Use Task.Delay
await Task.Delay(delay);

If the thread is returning to the pool, then it isn't going to do any more work in the method in question. Make the next bit of the method a separate method, and create a Timer that calls it.

You can use also a Timer for example:
using System.Timers;
private void Main()
{
Timer t = new Timer();
t.Interval = 5000; // 5 seconds
t.AutoReset = false;
t.Elapsed += new SleepDone(TimerElapsed);
t.Start();
}
private void SleepDone(object sender, ElapsedEventArgs e)
{
Console.WriteLine("HERE WHAT COME AFTER SLEEP");
}

Using Timer to delay an operation a few seconds

I am trying to delay my method by using a timer:
private System.Timers.Timer _delayTimer;
private void delay()
{
_delayTimer = new System.Timers.Timer();
_delayTimer.Interval = 5000;
//_delayTimer.Enabled = true;
_delayTimer.Elapsed += _delayTimer_Elapsed;
_delayTimer.Start();
someMethod();
}
}
private void _delayTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
// delay for 5 seconds
}
When i am get into delay() method i want to start the timer, than i want the 5 seconds delay and only after that i want to execute someMethod() and currently this not happen, after execute delay() the someMethod() executed without 5 seconds delay

Your current code sets up the timer and then immediately executes someMethod. Instead of this, you need to put the actual method call inside your Elapsed handler:
private void delay()
{
_delayTimer = new System.Timers.Timer();
_delayTimer.Interval = 5000;
//_delayTimer.Enabled = true;
_delayTimer.Elapsed += _delayTimer_Elapsed;
_delayTimer.Start();
}
}
private void _delayTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
someMethod();
}
And if there's nothing else you intend to do you can simply write this inline:
_delayTimer = new System.Timers.Timer();
_delayTimer.Interval = 5000;
_delayTimer.Elapsed += (o, e) => someMethod();
_delayTimer.Start();

If you're in .Net4.5(or using BCL.Async pack) you can use Task.Delay
private async void delay()
{
await Task.Delay(5000);
someMethod();
}
If you're under .Net4.5
Try the below code. I'll suggest you to use System.Threading.Timer
var timer = new System.Threading.Timer(x => someMethod(), null, 5000, System.Threading.Timeout.Infinite);\
Don't forget when you use Threading.Timer someMethod will be invoked in ThreadPool thread, If you're accessing UI you need to marshal the call to UI thread.

If you want the current thread to pause for five seconds, then call Thread.Sleep. For example:
Thread.Sleep(TimeSpan.FromSeconds(5));
DoSomething();
Use a timer if you want something to happen five seconds from now, while you're doing something else. When the timer elapses, the action will be executed on a thread pool thread.
Also, if you only want the timer to execute one time (rather than once every five seconds), be sure to set AutoReset to false.

You need to call someMethod in the timer's Elapsed handler:
private void delay()
{
_delayTimer = new System.Timers.Timer();
_delayTimer.Interval = 5000;
_delayTimer.AutoReset = false; //so that it only calls the method once
_delayTimer.Elapsed += (s,args) => someMethod();
_delayTimer.Start();
}
You could also use Task.Delay instead:
private void delay()
{
Task.Delay(5000)
.ContinueWith(t => someMethod());
}

System.Threading.Tasks.Task.Factory.StartNew(() =>
{
System.Threading.Thread.Sleep(5000);
/*
* Here Yopur code to do some method :D
* */
});

How do I show text on a label for a specific time (like 3 seconds)?

I have a statusbar label and I want to show a text on my StatusBar Label for 3 seconds only
How can I do it without using threads?
public void InfoLabel(string value)
{
if (InvokeRequired)
{
this.Invoke(new Action<string>(InfoLabel), new object[] { value });
return;
}
infoLabel.Text = value;
}

Simply add timer on the end of your method:
if (!string.IsNullOrWhiteSpace(value))
{
System.Timers.Timer timer = new System.Timers.Timer(3000) { Enabled = true };
timer.Elapsed += (sender, args) =>
{
this.InfoLabel(string.Empty);
timer.Dispose();
};
}

You need to define a function that you call each time you need to display your text, inside this function you define a timer, this timer is based on System.Windows.Forms.Timer, the only difference is that its modified to hold a stopTime parameter that represents the running duration, the only thing you need to do is to put your starting code(display text) inside the MyFunction function and to put the ending code(to stop displaying text) inside the Timer_Tick function, once you call MyFunction just specify how many seconds you want it to run in the function parameter.
private void MyFunction(int durationInSeconds)
{
MyTimer timer = new MyTimer();
timer.Tick += new EventHandler(Timer_Tick);
timer.Interval = (1000) * (1); // Timer will tick every second, you can change it if you want
timer.Enabled = true;
timer.stopTime = System.DateTime.Now.AddSeconds(durationInSeconds);
timer.Start();
//put your starting code here
}
private void Timer_Tick(object sender, EventArgs e)
{
MyTimer timer = (MyTimer)sender;
if (System.DateTime.Now >= timer.stopTime)
{
timer.Stop();
//put your ending code here
}
}
the modified timer class
public class MyTimer : System.Windows.Forms.Timer
{
public System.DateTime stopTime;
public MyTimer()
{
}
}

You can use Timer to create an instance of a timer that waits for n seconds before firing the Elapsed event. In the elapsed event, you clear the label's Content.
As the timer is executed in a separate thread, the UI thread is not locked while the timer is counting i.e. you are free to perform other operations in the UI.
private delegate void NoArgDelegate();
private void StartTimer(int durationInSeconds)
{
const int milliSecondsPerSecond = 1000;
var timer = new Timer(durationInSeconds * milliSecondsPerSecond);
timer.Start();
timer.Elapsed += timer_Elapsed;
}
private void timer_Elapsed(object sender, ElapsedEventArgs e)
{
var clearLabelTextDelegate = new NoArgDelegate(ClearLabelText);
this.Dispatcher.BeginInvoke(clearLabelTextDelegate);
}
private void ClearLabelText()
{
this.myLabel.Content = string.Empty;
}
As I do not the rest of your code, some suggestions would be to create a lock on the timer so as to prevent more than one UI event starting the timer. In addition, the delegate and the timer instance can be made as private members of the class.

You'll always be using at least the GUI thread. If you decide to wait on that thread, no other interaction with controls is possible (ie. no buttons will work, the window will not be repainted).
Alternatively you could use a System.Windows.Forms.Timer that gives control back to the OS, or another type of timer. Either way, the "countdown" will either block user interaction or happen on another thread (under the hood).

How to display the time elapsed in a label

What should be straight forward is not here and I couldnt find a way yet in spite of reading a lot.
I have a button which executes a time consuming function. So on clicking the button should show time elapsed in milliseconds in a label with an interval of 500 ms. And when the desired result is achieved I want the timer to stop. I dont just need the final time (the total time consumed) in a label, but the label should dynamically show the time being elapsed. My code would be:
private void btnHistory_Click(object sender, EventArgs e)
{
Class1 c = new Class1();
c.StartClock(ref label12);
Utility.PopulateHistory(dgvRecords_history, _util); //time consuming function
c.StopClock();
}
And in Class1 I write this:
internal void StartClock(ref Label l)
{
Timer t = new Timer();
t.Interval = 500;
t.Enabled = true;
t.Tag = l;
t.Tick += new EventHandler(t_Tick);
t.Start();
}
int i;
bool stop;
void t_Tick(object sender, EventArgs e)
{
if (stop)
{
((Timer)sender).Stop();
return;
}
((Label)((Timer)sender).Tag).Text = (++i).ToString();
}
internal void StopClock()
{
i = 0;
stop = true;
}
What happens is, the t_Tick event is fired only after the complete code under button event is fired. That is the tick event is fired after it goes through the StopClock function! I got no idea why on earth it should be that!
2 questions basically:
How can my requirement be achieved in the right way to handle these? I know I should use other built in classes to evaluate performance, but this is just for display purpose. For this, what is the ideal approach?
Why is my code not working?
EDIT: I have used here System.Windows.Forms Timer here, but the result is not any different with System.Timers Timer

The problem is that your long-running task is also running on the UI thread. So the timer can't fire and update the UI, since the thread is busy handling the long-running task.
Instead, you should use a BackgroundWorker to handle the long-running task.
In code:
private void btnHistory_Click(object sender, EventArgs e)
{
Class1 c = new Class1(ref label12);
c.StartClock();
var backgroundWorker = new BackgroundWorker();
backgroundWorker.DoWork += (s, e) =>
{
// time consuming function
Utility.PopulateHistory(dgvRecords_history, _util);
};
backgroundWorker.RunWorkerCompleted += (s, e) =>
{
c.StopClock();
};
backgroundWorker.RunWorkerAsync();
}
As ChrisWue noted, since you now have the long-running task in a separate thread, it needs to invoke any access to the UI controls on the UI thread.
If your long-running task just needs some data from the UI to start, you can pass that data as parameter of RunWorkerAsync(). If you need to output some result data to the UI, you can do that in the handler of the RunWorkerCompleted event. If you occasionally need to update the UI as progress is being made, you can do that in the handler of the ProgressChanged event, calling ReportProgress() in your DoWork handler.
If none of the above are needed, you could use the ThreadPool, as in StaWho's answer.

Your time consuming function is blocking the main thread. You can use BackgroundWorker or below trick:
public Form1()
{
InitializeComponent();
t.Tick +=new EventHandler(t_Tick);
t.Interval = 500;
}
int timeElapsed = 0;
System.Windows.Forms.Timer t = new System.Windows.Forms.Timer();
private void button1_Click(object sender, EventArgs e)
{
t.Start();
ThreadPool.QueueUserWorkItem((x) =>
{
TimeConsumingFunction();
});
}
void TimeConsumingFunction()
{
Thread.Sleep(10000);
t.Stop();
}
void t_Tick(object sender, EventArgs e)
{
timeElapsed += t.Interval;
label1.Text = timeElapsed.ToString();
}

Add the timer to the Components collection of the form. Or store the timer in a field in the class.
The timer is garbage collected because it is not longer reachable when your method returns.
I don't know about your long running code, but out should new run on a separate thread, or make calls to Application.DoEvents
(And remove the ref in your code, it is not used).

#Dainel Rose's answer worked for me perfectly, but only if invalid cross thread operation is handled. I could do so like:
private void btnHistory_Click(object sender, EventArgs e)
{
Class1 c = new Class1(ref label12);
c.StartClock();
var backgroundWorker = new BackgroundWorker();
backgroundWorker.DoWork += ((s, e) =>
{
// time consuming function
Utility.PopulateHistory(dgvRecords_history, _util);
});
backgroundWorker.RunWorkerCompleted += ((s, e) =>
{
c.StopClock();
});
backgroundWorker.RunWorkerAsync();
}
And in the Utility class where the time consuming function runs,
internal static void PopulateHistory(DataGridView dgv, Utility util)
{
SetDataGridView_History(dgv, util);
}
delegate void UpdateDataGridView_History(DataGridView dgv, Utility util);
static void SetDataGridView_History(DataGridView dgv, Utility util)
{
if (dgv.InvokeRequired)
{
UpdateDataGridView_History updaterDelegate = new UpdateDataGridView_History(SetDataGridView_History);
((Form)util._w).Invoke(updaterDelegate, new object[] { dgv, util });
}
else
//code that utilizes UI thread (long running process in my case)
}
Thanks all who helped. I'm marking Daniel's answer..