[AI Coding] The Essence of Asynchronous Processing! Mastering Compose with LaunchedEffect and produceState

I used to rely heavily on LaunchedEffect for handling asynchronous operations in Compose,but lately, I’ve realized that produceState might allow for a cleaner and more concise implementation.

So, I asked several AI assistants for their opinions and compared their responses.

🤔 GitHub Copilot

LaunchedEffect: Suitable for asynchronous operations that modify externally managed states (e.g., ViewModel).
produceState: Best for generating and managing asynchronous data directly within Compose.
Choose LaunchedEffect for externally managed state, and produceState for internally managed state.


@Composable
fun ExampleScreen(viewModel: MyViewModel = viewModel()) {
    // LaunchedEffect: Update externally managed state asynchronously
    val externalState by viewModel.uiState.collectAsState()
    LaunchedEffect(Unit) {
        viewModel.loadData() // Update external state asynchronously
    }

    // produceState: Generate and manage asynchronous data inside Compose
    val internalState by produceState(initialValue = "Loading...", key1 = viewModel) {
        value = viewModel.loadDataSync() // Assign result to internal state
    }

    Column {
        Text("LaunchedEffect State: $externalState")
        Text("ProduceState State: $internalState")
    }
}

🤔 ChatGPT

Use LaunchedEffect when updating existing state through side effects.
Use produceState when treating the result of an async operation as a state itself.
“Generate” with produceState, “manipulate” with LaunchedEffect.



@Composable
fun UserScreen(userId: String) {
    var user by remember { mutableStateOf<User?>(null) }
    LaunchedEffect(userId) { user = api.fetchUser(userId) } // Update existing state

    val userState by produceState<User?>(initialValue = null, key1 = userId) {
        value = api.fetchUser(userId) // Convert async result directly to state
    }

    Text("Launched: ${user?.name ?: "Loading..."}")
    Text("Produced: ${userState?.name ?: "Loading..."}")
}

🤔 Gemini

produceState: Ideal for exposing results of suspend functions or external data sources as reactive State for the UI.
LaunchedEffect: Tied to the composable’s lifecycle, suited for one-time async actions or UI event triggers (e.g., showing a snackbar).
State management: produceState handles state automatically, while LaunchedEffect requires manual updates via mutableStateOf.


@Composable
fun UserDataState(userId: String): State<User?> = produceState<User?>(
    initialValue = null,
    key1 = userId // Automatically restarts when key changes
) {
    value = fetchUserFromApi(userId)
}

@Composable
fun EventSnackbar(viewModel: MyViewModel) {
    val scope = rememberCoroutineScope() // Scope for showing snackbar
    LaunchedEffect(Unit) { // Runs once on first composition
        viewModel.uiEvents.collect { event ->
            // Receive UI event and trigger a side effect (e.g., show snackbar)
            scope.launch { SnackbarHostState.showSnackbar("Received event!") }
        }
    }
}

🤔 Summary

LaunchedEffect: Used when updating externally managed states (e.g., ViewModel) through asynchronous operations.
produceState: Used when generating and managing the result of asynchronous processing directly as state within Compose.
If the state is managed externally, use LaunchedEffect; if it’s internally generated, use produceState.
LaunchedEffect requires manual state updates, while produceState automatically manages state.
Use LaunchedEffect to update external state, and produceState to generate internal state.
LaunchedEffect manipulates existing state through side effects.
produceState creates new state from asynchronous results.
Operate state = LaunchedEffect / Generate state = produceState
produceState: Ideal for exposing asynchronous results as automatically managed State objects for the UI.
LaunchedEffect: Used to manually update existing states (e.g., ViewModel’s state) or trigger side effects such as showing a snackbar.
Where the state is managed: If it’s generated within Compose → use produceState.
Where the state is managed: If it’s controlled outside Compose (e.g., ViewModel) → use LaunchedEffect.