okay, I overlooked something important, I'm using ...

# announcements

[Fré Dumazy]

okay, I overlooked something important, I'm using coroutines in the method. So synchronized worked as it should. But can I use it in async(UI) { } or make sure this block isn't executed in parallel

[karelpeeters]

What's wrong with using syncronized for that too?

[Fré Dumazy]

After calling a suspend function in a synchronized block within a coroutine builder such as launch { } or async { }, you can (or always) get an IllegalMonitorStateException. I think this is because the coroutine might be continued on another thread, while the monitor provided in synchronized is on the initial thread.
The fix here was to use a Mutex object, pass it to the coroutine and replace synchronized(monitor) { } by mutex.withLock { }