android-kotlin（安卓 科特林）

When to use this skill

Use this skill whenever the user wants to:

• Create Android applications using Kotlin with Activities, Fragments, or Jetpack Compose
• Implement ViewModel, LiveData, StateFlow, or other Jetpack architecture components
• Configure Gradle build files (build.gradle.kts), dependencies, or build variants
• Set up navigation, permissions, or Android lifecycle handling
• Build and sign APK/AAB for release or configure ProGuard

How to use this skill

1. Project Setup

Create a new project with Android Studio or configure build files:

// build.gradle.kts (app module)
plugins {
    id("com.android.application")
    id("org.jetbrains.kotlin.android")
}

dependencies {
    implementation("androidx.core:core-ktx:1.12.0")
    implementation("androidx.lifecycle:lifecycle-viewmodel-ktx:2.7.0")
    implementation("androidx.navigation:navigation-fragment-ktx:2.7.6")
}

2. Architecture (MVVM with ViewModel)

class MainViewModel : ViewModel() {
    private val _items = MutableStateFlow<List<Item>>(emptyList())
    val items: StateFlow<List<Item>> = _items.asStateFlow()

    fun loadItems() {
        viewModelScope.launch {
            _items.value = repository.getItems()
        }
    }
}

3. UI with Jetpack Compose

@Composable
fun ItemList(viewModel: MainViewModel = viewModel()) {
    val items by viewModel.items.collectAsState()
    LazyColumn {
        items(items) { item ->
            Text(text = item.name, modifier = Modifier.padding(16.dp))
        }
    }
}

4. Navigation

Register destinations in the navigation graph and navigate programmatically:

findNavController().navigate(R.id.action_home_to_detail)

Best Practices

• Use viewModelScope for coroutines tied to ViewModel lifecycle; avoid leaking activities.
• Save UI state with SavedStateHandle in ViewModel; handle process death gracefully.
• Use ViewBinding or Jetpack Compose instead of findViewById.
• Apply ProGuard/R8 rules for release builds; keep signing keys secure.
• Test with @RunWith(AndroidJUnit4::class) and Espresso for UI tests.

Resources

• https://developer.android.com/kotlin
• https://developer.android.com/jetpack/compose
• https://developer.android.com/topic/architecture

Keywords

android, Kotlin, Jetpack, Compose, ViewModel, Navigation, Gradle, AndroidManifest.xml