android-app-development

name	android-app-development
description	Use when writing, reviewing, or scaffolding Android application components (Activity, Fragment, Service, BroadcastReceiver, ContentProvider) in either Android Studio (Gradle) or AOSP (Soong) build environments. Covers Android lifecycle, Intents, Permissions, AndroidManifest, Navigation, and app-level architecture conventions for Android Automotive / AAOS targets.
argument-hint	<component-or-feature-name> [write|review|debug]

Android App Development

Expert practices for building production-quality Android applications targeting Android Automotive OS (AAOS) IVI and RSE units, applicable equally in an Android Studio / Gradle project and in an AOSP source tree (Soong).

Standards baseline: Android API 33 (default minimum) · Kotlin primary, Java allowed for legacy.

---

When to Use This Skill

• Creating or reviewing an Activity, Fragment, Service, BroadcastReceiver, or ContentProvider.
• Designing or debugging app lifecycle transitions (resume/pause/stop/destroy).
• Configuring AndroidManifest.xml — permissions, components, intent filters.
• Implementing runtime permission requests and rationale flows.
• Setting up Navigation Component (NavController, NavGraph, destinations).
• Integrating an app into an AOSP product (Android.bp, product packages, signing).

---

Prerequisites

• Kotlin or Java (project-specific).
• Android Jetpack (lifecycle, navigation-fragment, activity-ktx).
• Hilt for dependency injection (see android-architecture skill).
• Build environment identified: Android Studio (Gradle) or AOSP (Soong).

---

Core Android Components

Activity

@AndroidEntryPoint // Hilt
class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        enableEdgeToEdge()
        setContentView(R.layout.activity_main)
        // or: setContent { MyTheme { NavHost(...) } }  // Compose entry
    }
}

Rules

• Use AppCompatActivity (or ComponentActivity for Compose-only screens).
• Never retain references to View or Activity context in a ViewModel.
• Use registerForActivityResult instead of deprecated onActivityResult.
• Persist transient state with onSaveInstanceState; use ViewModel for config-change state.

Fragment

@AndroidEntryPoint
class DashboardFragment : Fragment(R.layout.fragment_dashboard) {

    private val viewModel: DashboardViewModel by viewModels()

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        viewLifecycleOwner.lifecycleScope.launch {
            viewLifecycleOwner.repeatOnLifecycle(Lifecycle.State.STARTED) {
                viewModel.uiState.collect { render(it) }
            }
        }
    }
}

Rules

• Always use viewLifecycleOwner (not this) when observing LiveData or StateFlow.
• Avoid Fragment-to-Fragment direct dependencies — communicate via shared ViewModel or NavController.
• Prefer by viewModels() / by activityViewModels() over manual ViewModelProvider.

Service

Type	Base Class	Use Case
Foreground	Service + startForeground()	Media playback, navigation
Background (bounded)	Service + onBind()	IPC to other components
Intent-based	JobIntentService / WorkManager	Deferrable, guaranteed work

class MediaPlaybackService : Service() {
    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
        startForeground(NOTIFICATION_ID, buildNotification())
        return START_STICKY
    }
    override fun onBind(intent: Intent): IBinder? = null
}

Rule: Always stop or re-bind orphaned services. In AAOS, foreground services that play audio must use a MediaSession.

BroadcastReceiver

class BootReceiver : BroadcastReceiver() {
    override fun onReceive(context: Context, intent: Intent) {
        if (intent.action == Intent.ACTION_BOOT_COMPLETED) {
            // launch WorkManager jobs, not long-running tasks
        }
    }
}

Rules

• For sensitive broadcasts, register in manifest with android:exported="false" or appropriate permission.
• Never do long-running work in onReceive — delegate to WorkManager or a coroutine service.

---

AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android">

    <!-- Permissions -->
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.READ_MEDIA_IMAGES" />

    <application
        android:name=".MyApplication"
        android:label="@string/app_name"
        android:theme="@style/Theme.MyApp"
        android:networkSecurityConfig="@xml/network_security_config">

        <activity
            android:name=".ui.main.MainActivity"
            android:exported="true"
            android:launchMode="singleTask">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <!-- Automotive: opt-in to system UI templates -->
        <meta-data
            android:name="com.android.automotive"
            android:resource="@xml/automotive_app_desc" />

    </application>
</manifest>

Rules

• Always set android:exported explicitly (required Android 12+).
• Network security config must block http:// in production builds.
• Automotive apps must include automotive_app_desc.xml.

---

Permissions

Runtime permission request (Kotlin)

private val requestPermissionLauncher =
    registerForActivityResult(ActivityResultContracts.RequestMultiplePermissions()) { permissions ->
        val granted = permissions.entries.all { it.value }
        if (!granted) showPermissionRationale()
    }

fun requestMediaPermissions() {
    val permissions = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
        arrayOf(Manifest.permission.READ_MEDIA_IMAGES, Manifest.permission.READ_MEDIA_VIDEO)
    } else {
        arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE)
    }
    requestPermissionLauncher.launch(permissions)
}

Rules

• Check shouldShowRequestPermissionRationale() before re-request.
• Never request permissions at app start without user-initiated action context.
• AAOS: some android.car.* permissions are signatureOrSystem — only available to privileged apps.

---

Navigation Component

// NavGraph definition (nav_graph.xml)
<navigation app:startDestination="@id/homeFragment">
    <fragment android:id="@+id/homeFragment" android:name=".ui.home.HomeFragment">
        <action android:id="@+id/to_detail" app:destination="@id/detailFragment" />
    </fragment>
    <fragment android:id="@+id/detailFragment" android:name=".ui.detail.DetailFragment">
        <argument android:name="itemId" app:argType="string" />
    </fragment>
</navigation>

// Navigate
findNavController().navigate(HomeFragmentDirections.toDetail(itemId = id))

// Back
findNavController().navigateUp()

Rules

• Use Safe Args plugin for type-safe navigation arguments.
• Deep links: declare in manifest AND nav graph.
• Avoid calling navigate() in a Flow collect without checking currentDestination.

---

AOSP Integration

Android.bp — android_app module

android_app {
    name: "MyCarApp",
    srcs: ["src/**/*.kt", "src/**/*.java"],
    resource_dirs: ["res"],
    manifest: "AndroidManifest.xml",

    // Dependencies
    static_libs: [
        "androidx.lifecycle_lifecycle-viewmodel-ktx",
        "androidx.navigation_navigation-fragment-ktx",
        "car-ui-lib",
    ],
    libs: [
        "android.car",
    ],

    // Build config
    sdk_version: "current",          // or "33" for specific API
    min_sdk_version: "30",
    target_sdk_version: "33",

    // App characteristics
    privileged: true,                // place in /system/priv-app
    certificate: "platform",         // or "shared", "media", "testkey"
    product_specific: true,          // place in /product/priv-app

    // Optimization
    dex_preopt: {
        enabled: false,              // disable for faster build iterations
    },
}

Product package inclusion

# device.mk or product.mk
PRODUCT_PACKAGES += \
    MyCarApp

Key properties

Property	Effect
privileged: true	/system/priv-app — can request signatureOrSystem permissions
platform_apis: true	access hidden platform APIs (use sparingly)
certificate: "platform"	signed with platform key — can share UID with system
product_specific: true	placed in /product partition
vendor_specific: true	placed in /vendor partition

Rules

• Prefer sdk_version: "current" over platform_apis: true.
• Use platform_apis: true only when a hidden API is unavoidable and documented via @hide in AOSP source.
• Always verify with adb shell pm list packages -f | grep MyCarApp after flashing.

---

Lifecycle State Machine

Created → Started → Resumed (visible + focused)
          ↑               |
          └───── Paused ──┘
                    |
                  Stopped
                    |
                 Destroyed

Rules

• Start/stop animations, sensors, camera in onResume/onPause.
• Release heavy resources in onStop; restore in onStart.
• Observe Flow inside repeatOnLifecycle(Lifecycle.State.STARTED) to stop collection when app goes background.

---

Step-by-Step Workflows

Step 1: Define the component

Identify whether you need Activity, Fragment, Service, BroadcastReceiver, or ContentProvider.

Step 2: Register in AndroidManifest.xml

Add the component declaration with the correct intent-filter and permissions.

Step 3: Implement the lifecycle methods

Override only the callbacks you need; always delegate to super for others.

Step 4: Connect to ViewModel or Service

Use ViewModelProvider for UI logic; bind/start Services for background work.

Step 5: Test the component

Write unit tests for ViewModel logic and instrumented tests for the component lifecycle.

Troubleshooting

• Activity not launched / ActivityNotFoundException — verify intent-filter in AndroidManifest.xml; check action string and category.
• java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState — use commitAllowingStateLoss() only as a last resort; properly guard fragment transactions by lifecycle state.
• Memory leak via static Context — never store Activity or View in static fields; use ApplicationContext for long-lived components.
• Service killed by system — call startForeground() for long-running services; handle onTaskRemoved() for cleanup.

Pre-Commit Checklist

• No hardcoded strings — all in res/values/strings.xml.
• android:exported explicitly set on all manifest components.
• No Context stored in non-context-aware classes.
• Runtime permissions checked before accessing protected resources.
• Navigation: back stack managed — no duplicate destinations accumulation.
• AOSP: Android.bp certificate and partition placement verified.
• No System.out.println or bare Log.d without tag constant.

---

References

• Android App Architecture Guide
• Navigation Component Docs
• AOSP — Building Apps
• Android.bp Reference