I thought per default you observe on the Thread wh...

# rx

[mingkangpan]

I thought per default you observe on the Thread where you subscribe, but does the first function work, if the second doesn't?

[maciekjanusz]

How did you come to the conclusion that the first one doesn’t block?

[maciekjanusz]

And what is the thread calling these?

[mingkangpan]

I thought blockingFirst() is calling subscribe internally

[maciekjanusz]

well, yes

[maciekjanusz]

both of your calls are blocking, which is why you’re able to assign the val

[mingkangpan]

but first method doesn't freeze my app, second one does

[jossiwolf]

Because you are blocking the Main Thread, which is the UI Thread on Android.

[maciekjanusz]

Well, in the same sense you are blocking the main thread when assigning a value, like val a = 0

[maciekjanusz]

Observable.fromArray(1,2,3,4).blockingFirst() should complete instantly

[mingkangpan]

what I want to ask is, why does the second method completely freezes the app?

[maciekjanusz]

It shouldn’t, and your snippet is probably not enough to debug this. I suggest posting a question on stackoverflow