/dev-guide - Android Development Guide

Complete professional Android development guide covering best practices, patterns, and production workflows.

Learning Path

Beginner (100-150 hours)

1. Kotlin Fundamentals (30-40 hours)

   • Variables, functions, classes
   • Extension functions
   • Basic coroutines

2. Android Core (40-50 hours)

   • Activities and lifecycle
   • Fragments
   • Intents and navigation
   • Data persistence

3. First App Project (30-60 hours)

   • Simple todo app with database
   • Multiple screens
   • CRUD operations

Intermediate (100-150 hours)

1. Jetpack Modern (40-50 hours)

   • ViewModel and LiveData
   • Room database advanced
   • Navigation Component
   • Hilt dependency injection

2. Architecture Patterns (40-50 hours)

   • MVVM architecture
   • Repository pattern
   • Testing strategies
   • Design patterns

3. Real-World App (20-50 hours)

   • News app, weather app, or e-commerce
   • API integration
   • Database design
   • Multi-screen navigation

Advanced (100-200+ hours)

1. Production Quality (50-100 hours)

   • Performance optimization
   • Security best practices
   • Comprehensive testing
   • CI/CD setup

2. Capstone Project (50-100+ hours)

   • Complex real-world application
   • Complete architecture
   • Full test coverage
   • Play Store deployment

Tech Stack Recommendation

UI Layer:
- Activities/Fragments (or Jetpack Compose)
- Navigation Component
- Material Design 3

Architecture:
- MVVM with ViewModel
- Repository pattern
- Hilt for DI

Data:
- Room database
- Retrofit for APIs
- DataStore for preferences

Testing:
- JUnit 4/5
- Mockk for mocking
- Espresso for UI tests

DevOps:
- GitHub Actions
- Gradle build automation
- Play Store deployment

Project Structure

myapp/
├── app/
│   ├── src/main/
│   │   ├── java/
│   │   │   └── com/example/app/
│   │   │       ├── data/
│   │   │       │   ├── local/
│   │   │       │   ├── remote/
│   │   │       │   └── repository/
│   │   │       ├── domain/
│   │   │       │   ├── model/
│   │   │       │   └── repository/
│   │   │       ├── presentation/
│   │   │       │   ├── ui/
│   │   │       │   └── viewmodel/
│   │   │       └── di/
│   │   └── res/
│   ├── src/test/
│   └── src/androidTest/
├── build.gradle.kts
└── settings.gradle.kts

Best Practices

Code Quality

✅ Follow SOLID principles ✅ DRY (Don't Repeat Yourself) ✅ KISS (Keep It Simple, Stupid) ✅ Clean code practices ✅ Consistent naming conventions

Architecture

✅ Separation of concerns ✅ Dependency injection ✅ Repository pattern ✅ Testable design ✅ Single source of truth

Testing

✅ Unit tests for business logic (70%) ✅ Integration tests (20%) ✅ UI tests (10%) ✅ Mock external dependencies ✅ Aim for 80%+ coverage

Performance

✅ No memory leaks ✅ Efficient database queries ✅ Proper coroutine scoping ✅ 60+ FPS rendering ✅ Fast app startup

Security

✅ No hardcoded secrets ✅ HTTPS for all APIs ✅ Encrypted sensitive data ✅ Proper permission handling ✅ Input validation

Common Mistakes to Avoid

❌ Not understanding lifecycle ❌ Holding context in singletons ❌ Heavy operations on main thread ❌ Memory leaks from listeners ❌ Tight coupling between layers ❌ Skipping tests ❌ Not handling configuration changes ❌ Storing secrets in code

Development Workflow

1. Plan: Design architecture, data models
2. Setup: Create project, configure dependencies
3. Implement: Build features incrementally
4. Test: Write tests while coding
5. Optimize: Performance and memory profiling
6. Polish: UI/UX refinement
7. Release: Build, sign, deploy
8. Monitor: Track crashes and analytics

Tools & Libraries

Build

• Gradle, Kotlin DSL
• Gradle plugins

Architecture

• Jetpack (Compose, ViewModel, Room)
• Hilt for DI
• Retrofit for networking

Testing

• JUnit, MockK, Espresso
• Robolectric for faster tests

Code Quality

• Lint, Detekt
• SonarQube
• Jacoco for coverage

CI/CD

• GitHub Actions
• Firebase Test Lab
• Fastlane for automation

Success Criteria

✅ App runs without crashes ✅ 80%+ test coverage ✅ No memory leaks ✅ Performs at 60 FPS ✅ Follows SOLID principles ✅ Clear code structure ✅ Documented code ✅ Proper error handling ✅ Security reviewed ✅ Published on Play Store

Resources

• Android Official Docs
• Kotlin Docs
• Jetpack Guide
• Google Codelabs

Next Steps

1. Choose a learning path (Beginner/Intermediate/Advanced)
2. Follow the tech stack recommendation
3. Use code examples from /code-examples
4. Build projects incrementally
5. Test thoroughly
6. Deploy to Play Store
7. Monitor and iterate

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Ready to build professional Android apps? Start with the learning path above!