Hi guys. What is the difference between liveData {} and viewModelScope {} builders in ViewModel? Does liveData survive activity recreation?

If by activity re-creation you mean when an activity is recreated after a process death, no. However, if you mean configuration change (rotation, resize, etc), yes. I've never seen

viewModelScope{}

but

livedata{}

is used to create a Livedata using the ViewModel coroutine scope. (Using

emit

to emit values or

emitSource

to emit values from another Livedata) The

viewmodelScope

is a CoroutineScope scoped by the ViewModel lifecycle.

Yep, I mean exactly configuration change. I know that

viewModelScope{}

survives it, but I am not sure about

livedata{}

. Lets say I made a network request inside

livedata{}

and rotated screen couple of times - will the result arrive to observer ? Will it be cancelled if viewModel is destroyed and I moved to another activity?

The ViewModel itself survive configuration change. So with livedata you'll expose a Livedata and when the activity state will be started it's going to observe the value of the Livedata.

The block for

liveData {}

will stay alive for as long as the resulting

LiveData

has active observers, plus a configurable timeout. The default is non-zero and you can change it with a parameter to the

liveData {}

builder. Therefore if you start re-observing the same

LiveData

instance after a config change before the timeout expires, yes, the work happening in that block will continue.

I wasn't aware of the timeout 👍 Thank you for the clarification 🙂