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C# - Wait for 2s before doing next task

private void materialRaisedButton16_Click(object sender, EventArgs e)
{
foreach (var process in Process.GetProcessesByName("RobloxPlayerBeta"))
{
process.Kill();
}
materialRaisedButton16.Text = "Successfully killed process!";
// sleep for 2s WITHOUT freezing GUI
materialRaisedButton16.Text = "Click to kill process";
}
Hi, my code is above. I need the text of the button to change for 2s then change back to the original. How is this possible?
Thanks,
Tim

Implement like this
private async Task DelayTask()
{
await Task.Delay(2000); //2000 = 2sec
DoyourStuffHere();
materialRaisedButton16.Text = "Click to kill process";
}
And Call It Like This
private void materialRaisedButton16_Click(object sender, EventArgs e)
{
foreach (var process in Process.GetProcessesByName("RobloxPlayerBeta"))
{
process.Kill();
}
materialRaisedButton16.Text = "Successfully killed process!";
// sleep for 2s WITHOUT freezing GUI
Task taketime = this.DelayTask();
}

Not freezing the GUI requires some form of Mutlitasking. Possibly even Multithreading. Very strictly speaking calling a bunch of helper processes is a primitive form of Multithreading already. Possibly the oldest one, we invented just as we came off Cooperative Multitasking back in the days.
You have many Options to do Multitasking (inlcuding Multithreading) in .NET Async...await. Tasks. Threads. For beginners in Multithreading, I would advise BackgroundWorker generally. I wrote this little intro examples a few years back that I link often:
#region Primenumbers
private void btnPrimStart_Click(object sender, EventArgs e)
{
if (!bgwPrim.IsBusy)
{
//Prepare ProgressBar and Textbox
int temp = (int)nudPrim.Value;
pgbPrim.Maximum = temp;
tbPrim.Text = "";
//Start processing
bgwPrim.RunWorkerAsync(temp);
}
}
private void btnPrimCancel_Click(object sender, EventArgs e)
{
if (bgwPrim.IsBusy)
{
bgwPrim.CancelAsync();
}
}
private void bgwPrim_DoWork(object sender, DoWorkEventArgs e)
{
int highestToCheck = (int)e.Argument;
//Get a reference to the BackgroundWorker running this code
//for Progress Updates and Cancelation checking
BackgroundWorker thisWorker = (BackgroundWorker)sender;
//Create the list that stores the results and is returned by DoWork
List<int> Primes = new List<int>();
//Check all uneven numbers between 1 and whatever the user choose as upper limit
for(int PrimeCandidate=1; PrimeCandidate < highestToCheck; PrimeCandidate+=2)
{
//Report progress
thisWorker.ReportProgress(PrimeCandidate);
bool isNoPrime = false;
//Check if the Cancelation was requested during the last loop
if (thisWorker.CancellationPending)
{
//Tell the Backgroundworker you are canceling and exit the for-loop
e.Cancel = true;
break;
}
//Determin if this is a Prime Number
for (int j = 3; j < PrimeCandidate && !isNoPrime; j += 2)
{
if (PrimeCandidate % j == 0)
isNoPrime = true;
}
if (!isNoPrime)
Primes.Add(PrimeCandidate);
}
//Tell the progress bar you are finished
thisWorker.ReportProgress(highestToCheck);
//Save Return Value
e.Result = Primes.ToArray();
}
private void bgwPrim_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
pgbPrim.Value = e.ProgressPercentage;
}
private void bgwPrim_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
pgbPrim.Value = pgbPrim.Maximum;
this.Refresh();
if (!e.Cancelled && e.Error == null)
{
//Show the Result
int[] Primes = (int[])e.Result;
StringBuilder sbOutput = new StringBuilder();
foreach (int Prim in Primes)
{
sbOutput.Append(Prim.ToString() + Environment.NewLine);
}
tbPrim.Text = sbOutput.ToString();
}
else
{
tbPrim.Text = "Operation canceled by user or Exception";
}
}
#endregion
Of course in your case, something much simpler could work: A baseline Timer. All you really want is a 2 second delay? Make a TImer set to 2 seconds, no repeat, start it in "materialRaisedButton16_Click". And let it's tick to the rest. All true multithreading really does is allow you to write the same stuff in slightly more readable form (with some tradeoffs for performance).

the easiest way would be:
foreach (var process in Process.GetProcessesByName("RobloxPlayerBeta"))
{
process.Kill();
}
materialRaisedButton16.Text = "Successfully killed process!";
// sleep for 2s WITHOUT freezing GUI
Task.Delay(2000).ContinueWith(()=>{
materialRaisedButton16.Text = "Click to kill process";
}, TaskScheduler.FromCurrentSynchronizationContext()); // this is to make it run in the UI thread again

You can use Timer.
On its tick event you update the text of the button back to the value u need.

Pausing a BackgroundWorker from another method

I have a program that is continuously running.
When I start the program, I have a BackgroundWorker (InitialStart.cs):
BackgroundWorker recordingSyncWorker = new BackgroundWorker();
recordingSyncWorker.DoWork += new DoWorkEventHandler(RecordingSyncCheck);
recordingSyncWorker.WorkerSupportsCancellation = false;
recordingSyncWorker.WorkerReportsProgress = false;
recordingSyncWorker.RunWorkerAsync();
void RecordingSyncCheck(object sender, DoWorkEventArgs e)
{
cHandler ch = new cHandler();
Timer theTimer;
int seconds = 1;
if (taskSeconds != null && taskSeconds != "")
seconds = Convert.ToInt32(taskSeconds);
int milliseconds = seconds * 1000;
theTimer = new Timer(10000);
theTimer.Elapsed += new ElapsedEventHandler(ch.SyncMethod);
theTimer.Interval = milliseconds;
theTimer.Enabled = true;
}
And I have two methods in another class (cHandler.cs):
SyncMethod(object source, System.Timers.ElapsedEventArgs e)
{
// random code
}
private string SDCardCheck(object whatever)
{
//more code
}
SDCardCheck gets called thru WCF, so it's like there is another instance of cHandler.cs running. Is there a way for me to pause the BackgroundWorker when I call SDCardCheck?

Don't use a BackgroundWorker just to start a timer. Starting a timer is not a long running operation; it can be done directly from the UI thread.
Your other method can disable the timer to stop it from firing, and then enable it again to allow it to continue firing, in order to effectively pause its execution.

backgroundworker stops work,return only error

I'm writing an application for kinect sdk 1.8 with c#. I'm using a method to know if handpointer is hovering an interface element, this metod run in skeletonframeready.
public void CheckButton(Shape container, Point target, Point ContainerPoint)
{
// this allows our worker to report progress during work
// bw.WorkerReportsProgress = true;
bw = new BackgroundWorker();
bw.WorkerSupportsCancellation = true;
// what to do in the background thread
bw.DoWork += new DoWorkEventHandler(
delegate(object o, DoWorkEventArgs args)
{
BackgroundWorker b = o as BackgroundWorker;
_topBoundary = ContainerPoint.Y;
_bottomBoundary = _topBoundary + container.Height;
_leftBoundary = ContainerPoint.X;
_rightBoundary = _leftBoundary + container.Width;
//use midpoint of item (width or height divided by 2)
_itemLeft = target.X;
_itemTop = target.Y;
if (_itemTop < _topBoundary || _bottomBoundary < _itemTop)
{
//Midpoint of target is outside of top or bottom
args.Result = "no";
}
else if (_itemLeft < _leftBoundary || _rightBoundary < _itemLeft)
{
//Midpoint of target is outside of left or right
args.Result = "no";
}
else
{
args.Result = "yes";
}
});
// what to do when worker completes its task (notify the user)
bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(
delegate(object o, RunWorkerCompletedEventArgs args)
{
if (args.Error != null)
{
// here the app stops
Console.WriteLine(args.Error.Message);
}
else
{
// Finally, handle the case where the operation
// succeeded.
if (args.Result.ToString() == "yes")
{
//Hovering
}
else
{
//Not hovering
}
}
});
if (bw.IsBusy != true)
{
bw.RunWorkerAsync();
}
}
Until some hours ago this code works perfetly, now (without any modification) the code return always an error "The calling thread cannot access this object because a different thread owns it". What's wrong in this code?
EDIT
This is the calling of this method
CheckButton(Rect, Point, PointLeftTop);
I call the method in main thread with a Shape, the handpointer coordinate as poin and the top left point of the shape. With those parameters i knoweach cycle of the app if my handpointer is hover a determinated shape,the same that i have passed as parameter. What i expect from this method is : call from main thread, dowork in background thread (bw.DoWork) , return result in main thread (bw.RunWorkerCompleted).
The code stop here:
if (args.Error != null){
// here the app stops
Console.WriteLine(args.Error.Message);
}

Threading start back again after pausing

I am using threading in my code , thread are created using function:
private void InitializeBackgoundWorkers()
{
for (int f = 0; f < maxThreads; f++)
{
listBox1.Items.Insert(0, "Starting Thread : " + (f + 1));
threadArray[f] = new BackgroundWorker();
threadArray[f].DoWork +=
new DoWorkEventHandler(backgroundWorkerFiles_DoWork);
threadArray[f].RunWorkerCompleted +=
new RunWorkerCompletedEventHandler(backgroundWorkerFiles_RunWorkerCompleted);
threadArray[f].ProgressChanged +=
new ProgressChangedEventHandler(backgroundWorkerFiles_ProgressChanged);
threadArray[f].WorkerReportsProgress = true;
threadArray[f].WorkerSupportsCancellation = true;
}
}
And the doevent is something like :
private void backgroundWorkerFiles_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
int flag = 0;
while (rowCounter < allPostingRows.Tables[0].Rows.Count && flag == 0)
{
for (int i = 0; i < maxThreads; i++)
{
if (threadArray[i].CancellationPending == true)
{
flag = 1;
threadArray[i].CancelAsync();
worker.ReportProgress(0, "Thread Paused:");
}
}
if (flag == 0)
{
//perform work here
}
}
}
And on button i try to cancel the threads using:
for (int i = 0; i < maxThreads; i++)
{
threadArray[i].CancelAsync();
}
Am i cancelling the thread correctly? As when they get canceled i see the line in listbox saying thread cancelled so it does go to the cancellation code but after some time it restarts
Thank you

I don't think you really understand BackgroundWorker. The DoWork event handler is supposed to be a handler for one unit of work. DoWork is called with one thread. It doesn't make sense to call CancelAsync from within a DoWork handler--that's independent of any and all other BackgroundWorker's. Within the DoWork handler it should only be checking one CancellationPending, the sender's (once cast to BackgroundWorker, in your case worker).
But, otherwise, calling CancelAsync from the UI is the correct way to cancel a particular BackgroundWorker.
Background workers are not "thread"s. You''re not cancelling a thread, you're cancelling the worker--which allows the DoWork handler a chance to exit before it is done it's work.

Make sure all threads exited

In a win form application, I have an array of threads which are started like this:
bool stop = false;
Thread[] threads = new Thread[10];
for (int i = 0; i < threads.Length; i++)
threads[i] = new Thread(new ThreadStart(Job));
// How to make sure all threads have exited, when the boolean = false
void Job()
{
while (!stop)
// Do something
}
Now if user press STOP, the boolean value for stop will set to true, so threads exit the Job method one after another. How can I make sure all threads are exited?
NOTE: I need traditional threading for my case and TaskLibrary doesn't fit my scenario.

Use the Join method to check if all threads have stopped.
foreach (var t in threads)
{
t.Join();
}

Have you thought about using BackgroundWorkers instead? You said "traditional threads"..I'm not exactly sure what you mean so I don't know if this is a valid proposal or not, but here it is anyways in case Join() doesn't solve your problem
BackgroundWorker[] workers = new BackgroundWorker[10];
bool allThreadsDone = false;
// initialize BackgroundWorkers
for (int i = 0; i < 10; i++)
{
workers[i] = new BackgroundWorker();
workers[i].WorkerSupportsCancellation = true;
workers[i].RunWorkerCompleted +=
new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
workers[i].DoWork += new DoWorkEventHandler(AlgorithmsUI_DoWork);
workers[i].RunWorkerAsync();
}
// thread entry point..DoWork is fired when RunWorkerAsync is called
void AlgorithmsUI_DoWork(object sender, DoWorkEventArgs e)
{
while (!stop)
// do something
}
// this event is fired when the BGW finishes execution
private void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
bool threadsStillRunning = false;
foreach (BackgroundWorker worker in workers)
{
if (worker.IsBusy)
{
threadsStillRunning = true;
break;
}
}
if (!threadsStillRunning)
allThreadsDone = true;
}
protected override OnFormClosing(FormClosingEventArgs e)
{
if (!allThreadsDone)
{
e.Cancel = true;
MessageaBox.Show("Threads still running!");
}
}
This should prevent your form from closing if any threads are still running.

I'm not sure if this is what you're looking for, but here's a simple solution I used back in .NET 3.0 to make sure a large but deterministic number of threads had completed before continuing:
Global:
AutoResetEvent threadPoolComplete = new AutoResetEvent(false);
static int numThreadsToRun;
As you activate the threads:
numThreadsToRun = [number of threads];
[start your threads];
threadPoolComplete.WaitOne();
At the end of each thread's code:
if (Interlocked.Decrement(ref numThreadsToRun) == 0)
{
threadPoolComplete.Set();
}