Habit Tracker Android

A modern Android application for tracking daily habits and building streaks. Built with Jetpack Compose, Material 3 design, and Hilt dependency injection for a clean, scalable architecture.

Features

• ✨ Create & Manage Habits – Add, edit, and delete habits with a smooth bottom-sheet interface
• 📊 Habit Tracking – Check in daily to build habit streaks
• 🔥 Streak Counter – Visual streak display with animated fire icon that scales on new check-ins
• 🔄 Pull-to-Refresh – Refresh habit list with Material 3 pull-to-refresh gesture
• 📱 Responsive Design – Optimized for various screen sizes
• 🌓 Dark Mode Support – Full dark mode with optimized contrast ratios
• 🔐 Secure Storage – Encrypted local storage using Tink
• 🎯 Pagination – Efficient list loading with Paging 3
• ♿ Accessibility – Custom accessibility actions and semantic annotations

Tech Stack

Architecture & UI

• Jetpack Compose – Modern declarative UI framework
• Material 3 – Latest Material Design components and theming
• Jetpack Navigation Compose – Type-safe navigation
• Jetpack Hilt – Dependency injection framework
• Paging 3 – Efficient pagination with lazy loading

Data & Storage

• Room – Local SQLite database with Kotlin coroutines support
• Retrofit – Type-safe HTTP client for API calls
• Tink Android – Encrypted storage for sensitive data
• Android Security Crypto – Secure SharedPreferences wrapper

Testing

• JUnit 4 – Unit testing framework
• Mockk – Mocking library for Kotlin
• Turbine – Flow testing utility
• Espresso Core – UI testing framework
• Hilt Android Testing – Dependency injection for tests
• LeakCanary – Memory leak detection (debug builds)

Minimum Requirements

• Minimum SDK: 26 (Android 8.0)
• Target SDK: 37
• Compile SDK: 37
• Java: Version 17

Project Structure

build.gradle.kts                        # Root Gradle build configuration
settings.gradle.kts                     # Module/plugin settings
gradle.properties                       # Shared Gradle flags and behavior
gradlew                                 # Unix Gradle wrapper
gradlew.bat                             # Windows Gradle wrapper
app/
├── build.gradle.kts                    # App module build configuration
├── proguard-rules.pro                  # ProGuard/R8 rules
└── src/
    ├── main/
    │   ├── AndroidManifest.xml         # App manifest and entry points
    │   ├── java/com/davidread/habittracker/
    │   │   ├── common/                 # Shared app infrastructure and utilities
    │   │   ├── list/                   # Habit list feature module
    │   │   ├── login/                  # Login feature module
    │   │   ├── settings/               # Settings feature module
    │   │   └── signup/                 # Sign-up feature module
    │   └── res/                        # Android resources
    │       ├── values/                 # Strings, colors, themes
    │       └── drawable/               # Images and vector assets
    ├── test/                           # Unit tests
    └── androidTest/                    # Instrumentation tests
gradle/
├── libs.versions.toml                  # Centralized dependency management
└── wrapper/                            # Gradle wrapper files

Building & Running

Prerequisites

• JDK 17 or higher
• Android Studio (latest stable recommended) compatible with AGP 9.2.0 (or IntelliJ IDEA with Android plugin)
• Android SDK Platform 36

Build Variants

The project includes multiple build variants for different environments:

• debug – Local development build
• localHostDebug – Debug build connected to localhost API (clear text traffic enabled)
• mockInAppDebug – Debug build with mock in-app responses
• release – Production release build

Build Instructions

1. Clone the repository:

   git clone https://github.com/david-read-iii/habit-tracker-android
   cd habit-tracker-android

2. Build debug APK:

   ./gradlew :app:assembleDebug

3. Run on connected device or emulator:

   ./gradlew :app:installDebug

4. Build release APK:

   ./gradlew :app:assembleRelease

IDE Setup (Android Studio)

1. Open the project in Android Studio
2. Wait for Gradle sync to complete
3. Select a build variant (debug, localHostDebug, etc.) from Build → Select Build Variant
4. Run the app using Run → Run 'app' or Shift+F10

Testing

Run all tests:

./gradlew test

Run unit tests only:

./gradlew :app:testDebugUnitTest

Run instrumentation tests on a device:

./gradlew :app:connectedAndroidTest

Run debug-specific instrumentation tests:

./gradlew :app:connectedDebugAndroidTest

Architecture

The app follows MVVM with MVI (Model-View-Intent) pattern:

• ViewModel – Manages UI state and processes user intents
• ViewState – Immutable state representation
• ViewIntent – User actions/events
• ViewEffect – One-time side effects (navigation, snackbars)

Data Flow

UI Event → Intent → ViewModel → State Update → Compose Recomposition → UI

Theming

The app uses Material 3 dynamic theming with custom color schemes:

• Light Theme – Optimized for daylight viewing
• Dark Theme – Enhanced dark mode with improved contrast for text buttons
• Accessible Colors – WCAG AA compliant contrast ratios
• Customizable – Theme tokens in common/ui/theme/

Accessibility

The app includes comprehensive accessibility support:

• Content Descriptions – All icons and images have descriptive labels
• Custom Accessibility Actions – Swipe actions exposed via accessibility APIs
• Semantic Annotations – Proper role and traversal order assignments
• Announcements – Screen reader announcements for key events

Development Guidelines

Code Style

• Follow Kotlin style conventions
• Use meaningful variable and function names
• Prefer immutable data structures
• Keep composables focused and small

Composable Best Practices

• Use remember for state management
• Leverage composition locals for theme access
• Provide default parameters for preview compatibility
• Add @Preview composables for UI verification

Testing Best Practices

• Write unit tests for ViewModels and business logic
• Test state transitions and side effects using Turbine
• Use Mockk for dependency mocking
• Add instrumentation tests for critical user flows

Build Variants Details

Debug

Standard development build with debugging enabled.

LocalHostDebug

Connects to a local API server. Clear text traffic is enabled for localhost. Use this when developing against a local backend.

MockInAppDebug

Uses mock responses for API calls without needing a backend server. Useful for UI development and testing.

Release

Production build with ProGuard/R8 optimizations. Debugging is disabled.

Performance Considerations

• Paging – Large habit lists are paginated to reduce memory footprint
• Lazy Loading – Compose only renders visible items in lazy lists
• LeakCanary – Memory leaks are detected in debug builds
• R8/ProGuard – Code shrinking and obfuscation in release builds

Security

• Encrypted Storage – Sensitive data is encrypted using Tink and EncryptedSharedPreferences
• Network Security – HTTPS enforced in production
• Clear Text Traffic – Disabled by default, only enabled in localhost debug variant
• Dependency Check – Regular updates of third-party libraries

Troubleshooting

Build Issues

Gradle sync fails:

• Clean and rebuild project artifacts: ./gradlew clean :app:assembleDebug
• Invalidate caches in Android Studio: File → Invalidate Caches

Compose compiler errors:

• Ensure Compose Compiler plugin is applied: kotlin-plugin-compose
• Clear build cache: ./gradlew clean

Runtime Issues

No habits showing:

• Check database initialization
• Verify API connection
• Check logcat for errors

Accessibility features not working:

• Enable TalkBack or system accessibility service
• Verify semantic annotations in UI