Model: The Model component represents the data and business logic of the application. It encapsulates the data entities, database operations, network requests, and other backend-related functionality.
View: The View component represents the user interface and is responsible for displaying data to the user and capturing user input. It includes activities, fragments, layouts, and UI elements like buttons, text views, etc.
ViewModel: The ViewModel acts as an intermediary between the View and the Model. It contains the presentation logic and exposes data and commands that the View can bind to. It does not have a direct reference to the View, ensuring a separation of concerns.
Data Binding: Data Binding is a library provided by Android Jetpack that allows for seamless and declarative binding of data between the View and the ViewModel. It eliminates the need for manual updates and simplifies UI updates based on changes in the underlying data.
LiveData: LiveData is an observable data holder class also provided by Android Jetpack. It allows the ViewModel to expose data as LiveData objects that the View can observe. LiveData ensures that the View receives updated data whenever it changes, enabling automatic UI updates.
Observable: In some cases, the ViewModel may use the Observable pattern to notify the View of changes. Observables can be custom implementations or libraries like RxJava or Kotlin Coroutines.
Commands: The ViewModel can expose commands (e.g., button clicks) that the View can bind to. Commands encapsulate actions triggered by user interactions and provide a way to communicate from the View to the ViewModel.
Repository: The Repository serves as a single source of truth for data. It abstracts the data sources (e.g., local database, network) and provides methods for fetching and updating data. The ViewModel interacts with the Repository to access or modify the data.
Dependency Injection: Dependency Injection frameworks like Dagger or Hilt can be used to inject dependencies into the ViewModel and other components of the MVVM architecture. This promotes modularization, testability, and decoupling of dependencies.