android-development

name	android-development
description	Android development guidelines for Kotlin with clean architecture, MVI pattern, Material Design, and best practices for building robust mobile applications

Android Development Best Practices

General Kotlin Guidelines

Basic Principles

• Use English for all code and documentation
• Always declare variable and function types explicitly
• Avoid the any type; create necessary custom types
• Eliminate blank lines within function bodies

Naming Standards

• PascalCase: Classes, interfaces, enums
• camelCase: Variables, functions, methods
• underscores_case: Files and directories
• UPPERCASE: Environment variables, constants
• Avoid magic numbers; define constants instead
• Functions should start with action verbs
• Boolean variables use prefixes: isLoading, hasError, canDelete

Function Design

• Keep functions under 20 instructions with single responsibility
• Use verb-based naming
• Prefix boolean returns with is, has, or can
• Prefix void returns with execute, save, send
• Combat nesting through early returns, utility extraction, and higher-order functions
• Use default parameters instead of null checks
• Consolidate parameters into objects (RO-RO pattern)

Data and Classes

• Employ data classes for data structures
• Encapsulate primitives in composite types; validate internally
• Favor immutability; use val for unchanging values
• Follow SOLID principles; prefer composition over inheritance
• Keep classes under 200 instructions, 10 public methods, 10 properties

Exception Handling

• Reserve exceptions for unexpected errors
• Catch exceptions only to fix anticipated issues or add context
• Create custom exception types for domain errors

Android Architecture

Clean Architecture

• Implement clean architecture with clear layer separation
• Use repository pattern for data persistence and caching
• Keep business logic in Use Cases or Interactors
• Separate concerns between UI, domain, and data layers

Project Structure

app/
├── data/           # Data sources, repositories, models
├── domain/         # Use cases, domain models, interfaces
├── presentation/   # UI components, ViewModels, state
└── di/             # Dependency injection modules

MVI Pattern

• Deploy MVI pattern for state and event management
• ViewModels manage UI state as a single immutable state object
• UI components observe state and render accordingly
• Handle user intents/events through a single entry point
• Keep side effects predictable and traceable

UI Development

Navigation

• Use Navigation Component for fragment and activity routing
• Define navigation graph for app flow
• Handle deep links through Navigation Component
• Implement safe args for type-safe navigation arguments

Main Activity Structure

• MainActivity manages primary navigation
• Use BottomNavigationView for main destinations (Home, Profile, Settings, etc.)
• Handle navigation state properly across configuration changes

View Binding and State

• Use ViewBinding for type-safe view access
• Use Flow or LiveData for UI state management
• Observe state changes in lifecycle-aware manner
• Handle loading, error, and success states consistently

UI Framework Preferences

• Prefer XML layouts and Fragments over Jetpack Compose (unless Compose is specifically required)
• Use ConstraintLayout for complex layouts
• Apply Material 3 design guidelines
• Follow responsive design practices for different screen sizes

Authentication Flow

Structure authentication screens properly:

1. Splash Screen - Initial app launch
2. Login Screen - User authentication
3. Register Screen - New user registration
4. Forgot Password Screen - Password recovery
5. Verify Email Screen - Email verification

Testing

Unit Testing

• Follow Arrange-Act-Assert conventions
• Test ViewModels, Use Cases, and Repositories
• Use test doubles for dependencies
• Achieve good coverage of business logic

UI Testing

• Implement widget testing for UI components
• Write integration tests for API modules
• Test navigation flows
• Use Espresso for instrumented tests

Best Practices

Lifecycle Management

• Handle lifecycle events properly
• Avoid memory leaks from improper lifecycle handling
• Use lifecycle-aware components

Background Processing

• Use Coroutines for async operations
• Handle cancellation properly
• Use WorkManager for deferrable background work

Dependency Injection

• Use Hilt or Dagger for dependency injection
• Scope dependencies appropriately
• Keep DI configuration organized

Performance

• Avoid work on the main thread
• Optimize RecyclerView with DiffUtil
• Use lazy loading for heavy resources
• Profile and optimize memory usage