Android Jetpack Compose Expert

Overview

A comprehensive guide for building production-quality Android applications using Jetpack Compose. This skill covers architectural patterns, state management with ViewModels, navigation type-safety, and performance optimization techniques.

When to Use This Skill

• Use when starting a new Android project with Jetpack Compose.
• Use when migrating legacy XML layouts to Compose.
• Use when implementing complex UI state management and side effects.
• Use when optimizing Compose performance (recomposition counts, stability).
• Use when setting up Navigation with type safety.

Step-by-Step Guide

1. Project Setup & Dependencies

Ensure your libs.versions.toml includes the necessary Compose BOM and libraries.

[versions]
composeBom = "2024.02.01"
activityCompose = "1.8.2"

[libraries]
androidx-compose-bom = { group = "androidx.compose", name = "compose-bom", version.ref = "composeBom" }
androidx-ui = { group = "androidx.compose.ui", name = "ui" }
androidx-ui-graphics = { group = "androidx.compose.ui", name = "ui-graphics" }
androidx-ui-tooling-preview = { group = "androidx.compose.ui", name = "ui-tooling-preview" }
androidx-material3 = { group = "androidx.compose.material3", name = "material3" }
androidx-activity-compose = { group = "androidx.activity", name = "activity-compose", version.ref = "activityCompose" }

2. State Management Pattern (MVI/MVVM)

Use ViewModel with StateFlow to expose UI state. Avoid exposing MutableStateFlow.

// UI State Definition
data class UserUiState(
    val isLoading: Boolean = false,
    val user: User? = null,
    val error: String? = null
)

// ViewModel
class UserViewModel @Inject constructor(
    private val userRepository: UserRepository
) : ViewModel() {

    private val _uiState = MutableStateFlow(UserUiState())
    val uiState: StateFlow<UserUiState> = _uiState.asStateFlow()

    fun loadUser() {
        viewModelScope.launch {
            _uiState.update { it.copy(isLoading = true) }
            try {
                val user = userRepository.getUser()
                _uiState.update { it.copy(user = user, isLoading = false) }
            } catch (e: Exception) {
                _uiState.update { it.copy(error = e.message, isLoading = false) }
            }
        }
    }
}