Android App Development

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

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

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