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In WinForms, how do I force an immediate UI update from UI thread?
What I'm doing is roughly:
label.Text = "Please Wait..." try { SomewhatLongRunningOperation(); } catch(Exception e) { label.Text = "Error: " + e.Message; return; } label.Text = "Success!"; Label text does not get set to "Please Wait..." before the operation.
I solved this using another thread for the operation, but it gets hairy and I'd like to simplify the code.
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In this case, to update the UI from a background thread, you can create a handler attached to the UI thread, and then post an action as a Runnable : Handler handler = new Handler(Looper. getMainLooper()); handler. post(new Runnable() { @Override public void run() { // update the ui from here } });
1) Have each thread set a "DataUpdated" flag when new data is available, and have the UI periodically check for new data. 2) Create each thread with a callback to a UI Update(...) method to be called when new data becomes available.
At first I wondered why the OP hadn't already marked one of the responses as the answer, but after trying it myself and still have it not work, I dug a little deeper and found there's much more to this issue then I'd first supposed.
A better understanding can be gained by reading from a similar question: Why won't control update/refresh mid-process
Lastly, for the record, I was able to get my label to update by doing the following:
private void SetStatus(string status) { lblStatus.Text = status; lblStatus.Invalidate(); lblStatus.Update(); lblStatus.Refresh(); Application.DoEvents(); } Though from what I understand this is far from an elegant and correct approach to doing it. It's a hack that may or may not work depending upon how busy the thread is.
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