Are there any use cases for using Channels in Andr...

# coroutines

[Lukas Lechner]

Are there any use cases for using Channels in Android Development, or are you exclusively using Flows in your apps?

[luke_c]

We're using channels for one time events, as a replacement for SingleLiveEvent

[luke_c]

SharedFlow isn't a viable replacement as if an event is emitted when there's no subscribers it will be dropped

[Lukas Lechner]

@luke_c Hmm, but Google says we shouldn't use channels for one time events: https://medium.com/androiddevelopers/viewmodel-one-off-event-antipatterns-16a1da869b95

[luke_c]

In practice it's very unlikely it's going to be a problem... But I agree with the principal of handling events as state like the article mentions

[Lukas Lechner]

Okay, and as far as I understood, events can only stay unprocessed if send() and/or collect() are called on a different Dispatcher than Dispatchers.Main.immediate, which shouldn't be the case that often since lifecycleScope and viewModelScope use this dispatcher by default, right?

[luke_c]

Yes that's my understanding. It's important you use a buffered Channel so any events sent when there are no subscribers are buffered and not dropped

[Lukas Lechner]

Okay, by default they have a capacity of 0, so we have to set it to a value >0, correct?

[luke_c]

We use Channel.BUFFERED

One caveat is that Channels have a fan out behaviour, so it's not reliable if you need multiple observers, but that's generally not a problem for most people and the same limitation that SingleLiveEvent has