kotlin-flow-state-event-modeling

Use StateFlow for synchronous state reads and SharedFlow for event modeling with replay semantics. StateFlow requires an initial value and emits distinct updates, while SharedFlow supports replaying events to multiple subscribers.

To handle one-shot events safely, use Channel for synchronous event delivery or SharedFlow with appropriate replay semantics. Channels ensure events are consumed once, preventing lost events during complex state transitions.

The best way to update StateFlow atomically is using the update function. It applies atomic updates to MutableStateFlow, preventing race conditions during complex state transitions and ensuring thread-safe UI updates.

The stateIn function converts a cold Flow into a hot StateFlow by applying sharing strategies. It requires a SharingStarted strategy to control when sharing begins and ends, ensuring robust UI updates across Android and Kotlin projects.

Avoiding sentinel default values in StateFlow prevents stale values and complex state transitions. Using meaningful initial states instead of sentinels ensures error-resistant handling and correct flow composition for UI updates.

Channel offers synchronized event delivery for one-shot events, ensuring each event is consumed by exactly one collector. SharedFlow broadcasts events to all subscribers, making it suitable when multiple consumers need the same event.