android - Are there any special techniques for debugging third-party libraries?

Question

I want to use debug to see which method Schedulers.single() is.

Then I found something strange

The f here is obviously null but it is not directly return defaultScheduler?;
Why does it go to return apply(f,deaultScheduler) ;Is there something wrong with my source code? Or is there something wrong with the debug method?

Please give me some advice, I don’t understand this at all.

Answer 1

I think it is a debugging problem, Function f = onSingleHandler f is a Function type and has been assigned a non-null value onSingleHandler, so f != null
You can see that onSingleHandler is annotated as @Nullable’s

@Nullable
static volatile Function<? super Scheduler, ? extends Scheduler> onSingleHandler;