kotlin-android

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Original

English

🇨🇳

Translation

Chinese

Kotlin Android Skill

Kotlin Android 技能

Production-ready Android development with Jetpack libraries.

基于Jetpack库的可用于生产环境的Android开发。

Topics Covered

涵盖主题

MVVM Pattern

MVVM模式

kotlin

@HiltViewModel
class UserViewModel @Inject constructor(
    private val repository: UserRepository
) : ViewModel() {
    private val _uiState = MutableStateFlow(UiState())
    val uiState = _uiState.asStateFlow()

    fun load() = viewModelScope.launch {
        _uiState.update { it.copy(isLoading = true) }
        repository.getUsers()
            .onSuccess { users -> _uiState.update { it.copy(users = users, isLoading = false) } }
    }
}

kotlin

@HiltViewModel
class UserViewModel @Inject constructor(
    private val repository: UserRepository
) : ViewModel() {
    private val _uiState = MutableStateFlow(UiState())
    val uiState = _uiState.asStateFlow()

    fun load() = viewModelScope.launch {
        _uiState.update { it.copy(isLoading = true) }
        repository.getUsers()
            .onSuccess { users -> _uiState.update { it.copy(users = users, isLoading = false) } }
    }
}

Compose UI

kotlin

@Composable
fun UserScreen(viewModel: UserViewModel = hiltViewModel()) {
    val state by viewModel.uiState.collectAsStateWithLifecycle()
    UserContent(state)
}

kotlin

@Composable
fun UserScreen(viewModel: UserViewModel = hiltViewModel()) {
    val state by viewModel.uiState.collectAsStateWithLifecycle()
    UserContent(state)
}

Type-Safe Navigation

类型安全导航

kotlin

@Serializable
data class ProfileRoute(val userId: String)

composable<ProfileRoute> { entry ->
    val route: ProfileRoute = entry.toRoute()
}

kotlin

@Serializable
data class ProfileRoute(val userId: String)

composable<ProfileRoute> { entry ->
    val route: ProfileRoute = entry.toRoute()
}

Troubleshooting

问题排查

Issue	Resolution
Recomposition loop	Mark class @Stable or use derivedStateOf
ViewModel recreated	Use hiltViewModel() not viewModel()

问题	解决方法
重组循环	为类添加@Stable注解或使用derivedStateOf
ViewModel被重建	使用hiltViewModel()而非viewModel()

Usage

使用方法

Skill("kotlin-android")

Skill("kotlin-android")