Learning Android Development

Saving StateFlow State in ViewModel

Ensure your state flow value persist through process death

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Not too long ago, Google introduced an article on how one can migrate from LiveData to StateFlow. A great read.

Migrating from LiveData to Kotlin’s Flow

However, there’s no mention of how can one persist the StateFlow value across process death. Hence, here I explore the way to do so.

Manually Save and Retrieve the Value

For a normal flow, we can convert to StateFlow that is equivalent to LiveData as below.

val stateFlow = flow {
    emit(suspendFunc())
}.stateIn(
    scope = viewModelScope + Dispatchers.IO,
    started = SharingStarted.WhileSubscribed(5000L),
    initialValue = "Nothing"
)

This, however, means that whenever we start observing from it, it will start reading from suspendFunc() again, i.e. if the process kill the app, then all will start again.