Flows in Kotlin

Flow vs Stateflow vs Sharedflow

First, the Base Type: Flow<T>

• A cold asynchronous stream.

• Starts emitting only when collected.

• Use for standard data streams (e.g., database queries, API paginated responses).

fun getNumbers(): Flow<Int> = flow {
    emit(1)
    emit(2)
}

Then the Hot Ones: StateFlow and SharedFlow :

StateFlow<T>

• Hot flow — always active (even if no one is collecting).

• Keeps and exposes the latest value.

• Perfect for UI state (like screen loading state, user input, etc).

• Backed by MutableStateFlow (which you update).

• Think of it like LiveData from Android but for coroutines.

val state = MutableStateFlow("Loading...")

state.value = "Done!"

state.collect {
    println(it) // Always gets the latest value
}

SharedFlow<T>

• Also hot flow, but doesn’t keep a "latest value".

• More like an event bus — good for one-time events (like navigation, toasts).

• Supports multiple collectors at once.

• Tip: Use SharedFlow when:

  • You want to broadcast something once.

  • You don’t care about storing the latest value.

val events = MutableSharedFlow<String>()

launch {
    events.emit("Navigate to Home")
}

events.collect {
    println("Event received: $it")
}

Conclusion :