Learn Clean Architecture | App Architecture

Clean Architecture is a widely adopted approach for structuring Flutter applications to promote clear separation of concerns, scalability, and testability. This architecture organizes code into distinct layers, each with its own responsibilities, making it easier to maintain and extend your app as it grows. The three primary layers in Clean Architecture are: presentation, domain, and data.

Presentation Layer

The presentation layer handles user interface and user interaction logic. It is responsible for displaying data to users and reacting to their input, often using widgets, state management, and view models.

Domain Layer

The domain layer contains the business logic that is independent of any specific technology or framework. It defines entities, use cases, and interfaces (such as repositories) that describe how the app should behave.

Data Layer

The data layer is responsible for data sources and implementations, such as remote APIs, local databases, or device storage. This layer implements the interfaces defined in the domain layer and manages external dependencies.

By keeping these layers separate, you ensure that changes in one part of your app (like switching from a REST API to a local database) have minimal impact on other parts, and that business logic remains testable and reusable.

lib/presentation/user_profile_screen.dart

lib/domain/user_profile.dart

lib/domain/get_user_profile.dart

lib/data/user_profile_repository.dart


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import '../domain/get_user_profile.dart';
import '../domain/user_profile.dart';

class UserProfileScreen {
  final GetUserProfile getUserProfile;

  UserProfileScreen(this.getUserProfile);

  void display() {
    UserProfile profile = getUserProfile();
    print('Name: ${profile.name}');
  }
}

In the provided folder and file structure, each layer of Clean Architecture is represented with clear separation. The presentation layer contains user_profile_screen.dart, which is responsible for displaying user information and interacting with the domain layer. The domain layer holds the core business logic and contracts: user_profile.dart defines the user profile entity, and get_user_profile.dart defines a use case for retrieving a user profile. The data layer, represented by user_profile_repository.dart, provides the actual implementation for fetching data, such as simulating an API call.

Data flows from the data layer up to the presentation layer:

The presentation layer requests data by invoking a use case from the domain layer;
The domain layer relies on the data layer to fetch the actual data.

This structure keeps the UI decoupled from data sources, allowing you to modify or replace data implementations without affecting UI or business logic.

Which statement best describes the responsibilities of each layer in Clean Architecture for Flutter, and the main benefit of this separation?

Select the correct answer

All layers share the same responsibilities to reduce code duplication and increase performance

The presentation layer handles UI and user interaction, the domain layer contains business logic and use case definitions, and the data layer manages data sources and implementations; this separation improves testability and maintainability

The presentation layer manages data storage, the domain layer handles user input, and the data layer manages UI rendering; this makes the app run faster

The presentation layer defines business rules, the domain layer handles API requests, and the data layer manages state; this makes the app easier to deploy

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