Does Android really flow when you forget some kind of link in the background thread?
Yes Yes. This is a very good way to create leaks.
So, do we really need to call shouldStop in the onStop () activity of the callback?
Yes, you do this in the order 1) to prevent leaks, 2) to prevent your callbacks from being triggered after the death of the launching context, which can lead to a crash. But you're right, javadocs can be confusing. ShouldStopAndJoin is called for testing (see Its as private + tests) and shouldStop is public.
Even if the actions or fragments were leaking, the application should not, right?
Right. , , , Java. , shouldStop .