Hey anyone aware of a way to `collect` just once from a `StateFlow` or `SharedFlow` One can call `cancel ` on the job of the coroutine that is collecting but that seems a bit cumbersome

Hey anyone aware of a way to `collect` just once from a `Sta kotlinlang #coroutines

12/13/2020, 9:25 PM

Hey, anyone aware of a way to

collect

just once from a

StateFlow

SharedFlow

? One can call

cancel()

on the job of the coroutine that is collecting but that seems a bit cumbersome...

12/13/2020, 9:45 PM

first()

12/13/2020, 10:02 PM

first()

unfortunately has different behavior from

collect()

in that it throws an exception when the flow is empty.

12/13/2020, 10:02 PM

firstOrNull

12/13/2020, 10:03 PM

firstOrNull

also has different behavior. It returns null if the flow is empty where

collect

would just block and wait until there is something.

12/13/2020, 10:05 PM

StateFlow always has a value, StateFlow and SharedFlow also never complete

AFAIK a Flow is only seen as empty if it completes without emiting, since SharedFlow (and StateFlow) never complete, they can’t be empty then.

12/13/2020, 10:08 PM

I think I saw an exception being thrown by
first()
when I was using it on a
SharedFlow
(with no initial value).

collect()

SharedFlow

no exception is thrown.

But let me double check.

12/13/2020, 10:11 PM

incidentally, on StateFlow I’d just read

value

since reading that code it will be more clear it will not suspend (

first

behaves the same in this case but on other Flows like SharedFlow it can suspend)

12/13/2020, 10:19 PM