Model
The model represents the state of the UI and holds the necessary data for rendering. It should be an immutable object that reflects the current UI state. The model can be a simple data class or a more complex state machine, depending on the complexity of your UI.
View
The view is responsible for rendering the UI based on the model’s state. It should be a passive component without any business logic. The view observes changes in the model and updates itself accordingly. Android’s View or Fragment classes typically serve as the UI representation.
Intent
The intent represents the user’s action or intention to perform an operation in the UI. It can be triggered by user interactions, system events, or any other action. Intents are dispatched to the business logic layer to handle the user’s actions. Intents can be simple objects or events that encapsulate the user’s intention.
In the MVI (Model-View-Intent) pattern, the flow of data and actions follows a unidirectional cycle, which means the data flows in a single direction, ensuring a clear and predictable pattern for managing state and UI updates. The unidirectional cycle ensures that the data flows in a clear and consistent manner, making it easier to understand the flow of actions and states within the app. It also simplifies debugging and testing since the data flow is more predictable.
Reactive programming
Libraries like RxJava or Kotlin Coroutines provide a convenient way to handle asynchronous events and data streams. They enable you to observe and react to changes in the model or user intents.
LiveData or StateFlow
Android’s LiveData or Kotlin’s StateFlow can be used as observable data holders to represent the model’s state. These components can be observed by the view to update the UI reactively.
ViewModel
Android’s ViewModel class can be used to store and manage the state of the model. It survives configuration changes (such as screen rotations) and provides an easy way to share data between the business logic and UI components.
Event-driven architecture
You can use event-driven approaches to handle user intents and communicate between components. This can involve implementing interfaces or using event bus libraries to decouple the view and business logic.
Implementing MVI in Android typically involves using reactive programming libraries like RxJava or Kotlin Coroutines to handle asynchronous events and data streams. Libraries such as LiveData, ViewModel, and StateFlow can also be used to simplify the integration with Android components like activities and fragments.
By following the MVI pattern, you can achieve a more predictable and maintainable codebase. It helps separate concerns, simplifies testing, and provides a clear flow of data and actions in your Android app.
Overall, MVI provides a structured and predictable approach to building Android apps, making them easier to understand, test, and maintain, especially in complex UI scenarios.