stateInDelayed

Converts a Flow to a StateFlow with a 5-second stop timeout for improved performance.

This extension function is a convenience wrapper around stateIn that uses SharingStarted.WhileSubscribed(5000L) to automatically stop the upstream flow 5 seconds after the last subscriber unsubscribes. This prevents unnecessary work when there are no active collectors.

When to Use

Use this when you want to:

• Convert a cold Flow (like Room database queries) into a hot StateFlow

• Keep the flow active briefly after the last subscriber leaves (e.g., during configuration changes)

• Avoid restarting expensive operations during brief UI lifecycle transitions

Common Use Cases

// In a ViewModel - observe database with automatic lifecycle management
class MyViewModel(repository: MyRepository) : ViewModel() {
    val users: StateFlow<List<User>> = repository.observeUsers()
        .stateInDelayed(
            initialValue = emptyList(),
            scope = viewModelScope
        )
}

// In a Repository - expose Flow as StateFlow
class MyRepository(private val database: MyDatabase) {
    fun observeUsers(): Flow<List<User>> = database.userDao().observeAll()
}

Why 5 Seconds?

The 5-second delay is optimal for:

• Configuration changes (screen rotation) - typically complete in < 1 second

• Brief app backgrounding - keeps data ready for quick return

• Navigation transitions - prevents unnecessary restarts

While still stopping the flow quickly enough to avoid resource waste when the user truly leaves the screen.

Performance Benefits

// Without delay (restarts on every rotation)
val users = repository.observeUsers()
    .stateIn(viewModelScope, SharingStarted.WhileSubscribed(), emptyList())

// With delay (survives rotation, avoids restart)
val users = repository.observeUsers()
    .stateInDelayed(emptyList(), viewModelScope)  // ← Preferred

Parameters

See also