Sample Users App

This is a sample Android application built to demonstrate modern Android development practices. The app fetches a list of users from a remote API, displays them in a list, and allows the user to view the details of each user. It also includes functionality to add a new user to the list locally.

App Flow & Features

1. Users List: The main screen fetches and displays a list of users from the dummyjson.com API.
2. User Details: Tapping on a user in the list navigates to a details screen, showing more information about the selected user.
3. Add User: A Floating Action Button allows the user to add a new, hardcoded user to the list. After adding, the app automatically navigates to the details screen for this new user.
4. Image Loading: User profile pictures are loaded asynchronously from URLs using Coil.

Architecture

The project follows the Clean Architecture principles, separating the codebase into three main layers:

• data: This layer is responsible for all data-related operations. It includes the API service definition (Retrofit), data transfer objects (DTOs), and the repository implementation that fetches data from the remote source and manages an in-memory cache.
• domain: This is the core layer of the application. It contains the business logic, defining the data models (UserModel) and the repository interface (IUserRepository) that the UI layer will interact with. This layer has no knowledge of the Android framework.
• ui: This layer is responsible for the presentation. It is built entirely with Jetpack Compose and follows the Model-View-ViewModel (MVVM) design pattern. It contains the Composable screens, ViewModels, and navigation logic.

MVVM Pattern

The MVVM pattern is used to separate the UI from the business logic:

• View: The Composable functions (UsersView, UserDetailsView) that observe data from the ViewModel and render the UI. They delegate all user actions to the ViewModel.
• ViewModel: (UsersViewModel, UserDetailsViewModel) It acts as a bridge between the View and the data layer (via the repository). It holds the UI state, processes user actions, and provides data streams that the UI can observe.
• Model: The data entities defined in the domain layer (UserModel), which are manipulated by the repository and exposed to the UI by the ViewModel.

Key Dependencies

• Jetpack Compose: For building the UI declaratively.
• Hilt: For dependency injection, which simplifies providing dependencies like the repository and API service.
• Retrofit: For making network requests to the REST API.
• Gson: For parsing JSON data from the API responses.
• Coil 3: For loading and displaying images asynchronously.
• Jetpack Navigation for Compose: For handling navigation between screens.
• Lifecycle-ViewModel-Compose: For integrating ViewModels with the Composable lifecycle.

Data Flow PlantUML Diagram

Here is a diagram illustrating the flow of data from the remote API to the UI for displaying the user list.