Is there any “strict mode” to check if I edit some view outside the main thread? I’m getting some st...

# android

[Brais Gabin]

Is there any “strict mode” to check if I edit some view outside the main thread? I’m getting some strange crashes that doesn’t point to any line of my code. I think that those errors are related with a notifyDataSetChanged or a setText performed outside the main thread. The problem is that the app is huge and those errors are race exceptions so they are not easy to reproduce. For that reason I’ll need some “tool” that checks that all the interactions done with view is done in the main thread. Any idea?

[trevjones]

from rxandroid MainThreadDisposable:

if (Looper.myLooper() != Looper.getMainLooper()) {
  throw new IllegalStateException("Expected to be called on the main thread but was " + Thread.currentThread().getName());
}

I like to wrap that logic up in a function and call it from all over the points that you suspect are being accessed illegally. requireMainThread

[Brais Gabin]

Yeah… the problem is that I have no idea what’s going on >_<. For that reason I was wondering. The same way that strict mode checks that no I/O work is done in the main thread. Is there something that checks that no UI work is done outside the main thread?

[trevjones]

the layout/draw system can sometimes detect it if it happens at specific timing, otherwise no I don't believe so. to which I invite peppering the code with a requireMainThread assertions

[trevjones]

only place I can find a check in the platform so far is android.view.ViewRootImpl#runOrPost(View source, int changeType) which gets hit from

notifySubtreeAccessibilityStateChanged(View child, View source, int changeType)

so only a specific set of changes checks it seems.

[trevjones]

and viewRootImpl.checkThread

[trevjones]

so lots of flows do check the thread

[Brais Gabin]

Yes, I was looking for a way to avoid that noise in the code. But I think that I should add it for test and then remove it... The problem is the size of the project.

[Brais Gabin]

But thanks for the answers!