Question

my winform has a thread running and I need it to notify main thread once it’s done, then the main thread can set progressbar back to normal state.

currently, what i have is something as following

------begin---------
// codes before....
call thread one....
create thread two instance then start thread two
---------end------------------

in thread two, i have

--------begin------
 while(threadOne.isalive){
   Thread.Sleep(500);
 }
 call setProgressbar delegate
 ---------end----------------

i did this instead of put an var in thread one is because thread one is recursive method….
i wonder if this correct way of doing it, can someone help?
thanks

Answer 1

EDIT: The answer below the line answers your explicit question, but if you’re using .NET 4, you should consider thinking at a higher level of abstraction instead – tasks. The Task Parallel Library exposes a richer set of functionality than “bare” threads, and you can do things like registering continuations (with Task.ContinueWith) – and there you can even specify which task scheduler to use, so you can directly specify that when a background task has finished, a particular action should be invoked on the UI thread.

---

Original answer

The simplest way would be to delegate the first thread’s responsibility, e.g.

public void WrappedStart()
{
    bool success = false;
    try
    {
        StartWork();
        success = true;
    }
    finally
    {
        NotifyCompleted(success);
    }
}

private void StartWork()
{
    // Do your real work here
}

...

Thread t = new Thread(WrappedStart);
t.Start();

If your thread might do different things, you could change your WrapperStart to take the action to wrap:

public void WrappedStart(Action action)
{
    ...
}

Then:

Thread t = new Thread(() => WrappedStart(RealWork));
t.Start();

Note that if you do want the multi-thread solution, just use Thread.Join instead of looping explicitly.