JetpackPrep (Kotlin • Jetpack Compose • Hilt • Retrofit • Room • Paging)

A realistic Android interview practice app built with modern Jetpack libraries — designed to sharpen your architecture and UI skills.

🔍 Features

• Fetch posts from a public REST API (JSONPlaceholder)
• Display a paginated list with integrated search and filtering
• Navigate to details screens for individual items
• Work offline with Room database and a RemoteMediator for caching & sync
• Preserve state safely across configuration changes using ViewModel and SavedStateHandle

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🚀 Quickstart

Requirements

• Android Studio Hedgehog or newer (JDK 17)
• Android SDK 26+

Run

1. Open the project in Android Studio.
2. Sync Gradle.
3. Run the app configuration on an emulator or device.

Network: The app uses https://jsonplaceholder.typicode.com/ and does not require keys.

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🧱 Tech Stack

• Kotlin, Coroutines/Flow
• Jetpack Compose + Material 3 + Navigation
• Hilt for Dependency Injection
• Retrofit + OkHttp + Kotlinx Serialization for networking/JSON
• Room for local cache
• Paging 3 with RemoteMediator (offline-first)

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🧭 Architecture

• MVVM + Repository
• UI (Compose) observes StateFlow from ViewModels
• Repository coordinates network ↔ database
• RemoteMediator handles sync/pagination between server and Room

UI (Compose) ──observes──▶ ViewModel ──calls──▶ Repository ──▶ Retrofit (API)
                                         │
                                         └──▶ Room (Local cache)

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📂 Project Structure (suggested)

app/
  src/main/java/<your.package>/
    app/                    # App-wide bootstrapping (Application, DI)
    common/                 # Result wrappers, utils, constants
    data/                   # remote/ (Retrofit), local/ (Room), paging/, repository/
    domain/                 # models/, usecases/ (optional)
    presentation/           # ui/, screens/, components/, nav/
      ui/theme/             # Theme (colors/typography)

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🖥️ Main Activity (Compose entry)

Minimal example:

@AndroidEntryPoint
class MainActivity : ComponentActivity() {
  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContent {
      InterviewTheme {
        AppNavGraph() // startDestination = Home
      }
    }
  }
}

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🔍 Features

• Search with debounce + flatMapLatest
• Paging list (append/loading states, error/retry)
• Offline‑first (airplane mode after first load)
• Safe state on rotation (SavedStateHandle)
• Clean layering & DI

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🧪 Testing (starter ideas)

• Unit: Repository + ViewModel (fake API/DAO, kotlinx-coroutines-test)
• UI: Compose tests for the list & details render

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🧰 Troubleshooting

• Build fails JDK: Ensure Gradle JVM is set to 17 (File → Settings → Build Tools → Gradle).
• No internet: Check emulator has network or try on device.
• Room schema change: For quick iteration, use fallbackToDestructiveMigration() (already enabled in sample) but avoid for production.

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📌 Roadmap / Practice Tasks

• Add Retry UI for network errors
• Replace details workaround with DAO.getById(id)
• Add UI & unit tests
• Real server paging; remove client‑side slicing
• CI (GitHub Actions) for build & lint

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📜 License

MIT

Dev: ALAA EDDIN ALBARGHOTH