MVVM (Google Recommended) vs MVI

21 Aug, 2026

1. Input Processing (Events)

MVVM (Direct Method Calls)

UI triggers dedicated ViewModel methods directly.

Button(onClick = { viewModel.onSubmitClicked() })

MVI (Single Entry Point)

All UI actions are wrapped into a single Intent sealed interface and sent to one handler.

Button(onClick = { viewModel.onIntent(UserIntent.Submit) })

2. State Reduction (State Updates)

MVVM (Direct State Mutation)

State is updated directly inside asynchronous calls via _uiState.update { ... }.

fun loadData() {
    viewModelScope.launch {
        val result = repository.getData()
        _uiState.update { it.copy(data = result) }
    }
}

MVI (Pure Reducer Function)

The next state is calculated via a pure reduce function based on the current state and the received action.

fun reduce(oldState: UiState, action: Action): UiState = when (action) {
    is Action.DataLoaded -> oldState.copy(data = action.data)
    is Action.Loading -> oldState.copy(isLoading = true)
}

3. Output Processing (UI Updates & Side Effects)

MVVM (State-Driven Single Flow)

Both persistent state and one-off events are encapsulated inside a single UiState. Single-shot events are consumed and cleared by the UI.

val uiState: StateFlow<UiState> = _uiState.asStateFlow()

val state by viewModel.uiState.collectAsStateWithLifecycle()

LaunchedEffect(state.userMessage) {
    state.userMessage?.let {
        snackbarHostState.showSnackbar(it)
        viewModel.onMessageShown() // Consume event
    }
}

MVI (Separated Side Effects Flow)

State rendering and single-shot events are decoupled. Side effects stream through a Channel or SharedFlow.

private val _effect = Channel<UiEffect>()
val effect = _effect.receiveAsFlow()

val state by viewModel.state.collectAsStateWithLifecycle()

LaunchedEffect(Unit) {
    viewModel.effect.collect { effect ->
        when (effect) {
            is UiEffect.ShowSnackbar -> snackbarHostState.showSnackbar(effect.message)
        }
    }
}

4. Architecture Selection Guide

Criteria	Google Recommended MVVM	Pure MVI
Primary Goal	Pragmatic developer velocity	Strict state predictability
Boilerplate	Low to Moderate	High (Sealed classes for Intent, Action, Effect)
State Mutation	Scattered across ViewModel methods	Centralized inside Reducer
Ideal Team Size	Any team size	Mid to Large teams requiring strict patterns
Debugging	Standard break-pointing	Easy event logging & state snapshot inspection

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