Difference Between MVC, MVP, and MVVM Architecture Pattern in Android

MVC, MVP, and MVVM are architectural patterns designed to separate concerns in an application, facilitating modularity, maintainability, and testability. While they all aim to achieve this separation, they do so in distinct ways. Let's compare these patterns, particularly in the context of Android development:

Model-View-Controller (MVC):
- Model: Represents data and business logic.
- View: Displays the data to the user.
- Controller: Intermediary between Model and View. It takes user input from the View, processes it, and updates the Model and View accordingly.
In Android:
- Activity or Fragment often act as both Controller and View, which sometimes blurs the separation of concerns.
- Model is separate, typically interacting with data sources.
Model-View-Presenter (MVP):
- Model: Represents the data and business logic.
- View: Is passive and displays data given by the Presenter. It can be an Activity, Fragment, or a custom View.
- Presenter: Handles most of the logic. Acts upon the Model and updates the View. Unlike MVC's Controller, Presenter in MVP is more involved in processing UI logic.
In Android:
- View: Is typically an Activity, Fragment, or custom View. It's passive and delegates most tasks to its Presenter.
- Presenter: Handles most logic. It's decoupled from the Android framework, making it easier to test.
- Model: Remains the data access and business logic layer.
Model-View-ViewModel (MVVM):
- Model: Represents the data and business logic.
- View: Displays the data. It's passive and should not contain logic.
- ViewModel: Manages and prepares the data for the View. Provides data-binding between View and Model data. It's not meant to know View details.
In Android:
- View: Represented by an Activity or Fragment, but only for UI display.
- ViewModel: Holds and manages UI-related data in a lifecycle-conscious way. Android's Jetpack libraries introduced the ViewModel class to support this pattern.
- Model: Remains the data access and business logic layer.

Key Differences:

Interaction with the View:
- In MVC, the Controller directly updates the View.
- In MVP, the Presenter is responsible for updating the View but does so through an interface, ensuring decoupling.
- In MVVM, there's data-binding between the View and ViewModel, often eliminating the need for explicit updates.
Testability:
- MVC: Testing can be more challenging, especially since the Controller (in Android's implementation) can become tightly tied to the View.
- MVP: Improved testability because the Presenter is decoupled from the Android framework.
- MVVM: ViewModel can be easily tested as it's separated from the View layer and doesn't rely on Android framework components.
Modern Trends in Android:
- MVVM has become more popular in Android with the introduction of Jetpack libraries, especially the ViewModel and LiveData components. It aligns well with reactive programming paradigms.
- MVP was a favorite before the rise of MVVM in Android, as it provided a clear separation between the View and logic.
- MVC is seen less in modern Android apps due to the blurred lines between View and Controller in Android's implementation.

In summary, while MVC, MVP, and MVVM all aim to achieve separation of concerns, their approach varies. In the context of modern Android development, MVVM has gained significant traction due to tools and libraries that align well with this architecture, although the best choice often depends on the specific needs and complexities of the application.