How to distinguish architectural patterns MVI and MVVM and what are their main differences?

MVVM (Model-View-ViewModel) and MVI (Model-View-Intent) are architectural patterns for organizing code in Android applications, but they differ in their approach to state management and component interaction.

• MVVM:

  • ViewModel contains UI logic and state.
  • View subscribes to changes in ViewModel (usually via LiveData or Flow).
  • ViewModel updates the state, and View reacts to these changes.
  • The approach is oriented towards two-way data binding.

• MVI:

  • Based on a unidirectional data flow.
  • View generates an Intent (user's intentions).
  • Intents are processed, changing the Model's state.
  • View subscribes to the state and updates accordingly.
  • All application state is stored in a single State object, simplifying debugging and predictability.

Main differences:

• MVVM uses two-way data binding and ViewModel as an intermediary.
• MVI is built on a unidirectional data flow and immutable state.

Example of simplified MVI:

// Intent
sealed class UserIntent {
    object LoadData : UserIntent()
}

// State
data class ViewState(val isLoading: Boolean, val data: List<String>?, val error: String?)

// ViewModel processes Intent and updates State

Thus, the choice between MVVM and MVI depends on team preferences and requirements for state management.