/quick-help - Quick Help for Common Tasks

Fast reference for solving common Android development problems.

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Learn Android Development

If you're a beginner:

1. Start with /dev-guide
2. Review Kotlin Fundamentals agent
3. Study Android Core agent
4. Use /code-examples for reference

If you have experience:

1. Check Jetpack Modern agent
2. Review Architecture Patterns agent
3. Use /code-examples for patterns
4. Study Production Skill

Build a New App

1. Plan architecture (MVVM, Repository pattern)
2. Set up project with:
   - Jetpack (ViewModel, Room, Navigation)
   - Hilt for dependency injection
   - Retrofit for APIs
3. Implement features incrementally
4. Write tests (Unit + UI)
5. Optimize performance
6. Deploy to Play Store

Use ViewModel & LiveData

@HiltViewModel
class MyViewModel @Inject constructor(
    private val repository: MyRepository
) : ViewModel() {
    private val _state = MutableLiveData<State>()
    val state: LiveData<State> = _state

    fun doSomething() {
        viewModelScope.launch {
            _state.value = repository.getData()
        }
    }
}

// In Fragment
viewModel.state.observe(viewLifecycleOwner) { state ->
    updateUI(state)
}

Setup Room Database

@Entity
data class Item(@PrimaryKey val id: Int, val name: String)

@Dao
interface ItemDao {
    @Query("SELECT * FROM Item")
    suspend fun getAll(): List<Item>

    @Insert
    suspend fun insert(item: Item)
}

@Database(entities = [Item::class], version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun itemDao(): ItemDao
}

Use Dependency Injection (Hilt)

@HiltAndroidApp
class MyApp : Application()

@HiltViewModel
class MyViewModel @Inject constructor(
    private val repository: MyRepository
) : ViewModel()

class MyFragment : Fragment() {
    private val viewModel: MyViewModel by viewModels()
}

Make API Calls

interface ApiService {
    @GET("/items")
    suspend fun getItems(): List<Item>
}

val retrofit = Retrofit.Builder()
    .baseUrl("https://api.example.com/")
    .addConverterFactory(GsonConverterFactory.create())
    .build()

val api = retrofit.create(ApiService::class.java)
val items = api.getItems()  // In coroutine

Handle Navigation

// Navigate
findNavController().navigate(R.id.action_go_to_detail)

// With arguments
findNavController().navigate(
    MyFragmentDirections.actionGoToDetail(itemId = 123)
)

// Pop back stack
findNavController().popBackStack()

Write Unit Tests

@RunWith(RobolectricTestRunner::class)
class MyViewModelTest {
    private val repository = mockk<MyRepository>()
    private lateinit var viewModel: MyViewModel

    @Before
    fun setup() {
        viewModel = MyViewModel(repository)
    }

    @Test
    fun `test something`() {
        coEvery { repository.getData() } returns testData

        viewModel.doSomething()

        assertEquals(testData, viewModel.state.value)
    }
}

Test UI

@RunWith(AndroidJUnit4::class)
@HiltAndroidTest
class MyActivityTest {
    @get:Rule
    val activityRule = ActivityScenarioRule(MyActivity::class.java)

    @Test
    fun testButton() {
        onView(withId(R.id.button))
            .perform(click())

        onView(withId(R.id.result))
            .check(matches(withText("Expected text")))
    }
}

Store Sensitive Data

val encryptedPrefs = EncryptedSharedPreferences.create(
    context, "secret",
    MasterKey.Builder(context).setKeyScheme(MasterKey.KeyScheme.AES256_GCM).build(),
    EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
    EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
)

encryptedPrefs.edit { putString("token", "secret_value") }

Deploy to Play Store

1. Increment versionCode and versionName
2. Enable minification:
   minifyEnabled = true
3. Build release bundle:
   ./gradlew bundleRelease
4. Sign with keystore
5. Upload to Google Play Console
6. Configure app listing
7. Start staged rollout (5% → 25% → 100%)

Fix Memory Leaks

// ❌ LEAK
object Singleton {
    lateinit var context: Context
}

// ✅ FIX
object Singleton {
    var context: WeakReference<Context>? = null
}

// ✅ Also unregister listeners
override fun onDestroy() {
    super.onDestroy()
    unregisterReceiver()
}

Improve Performance

Memory:

• ✅ Avoid memory leaks
• ✅ Release large objects
• ✅ Use WeakReference when needed

Battery:

• ✅ Batch network requests
• ✅ Use WorkManager with constraints
• ✅ Optimize location updates

Rendering:

• ✅ Avoid main thread blocking
• ✅ Use RecyclerView for lists
• ✅ Lazy load images

Common Errors

"Can't create instance of ViewModel"

• Add @HiltViewModel annotation
• Check constructor parameters are provided by Hilt

"NullPointerException on view"

• Check layout file has the view with correct ID
• Verify view binding is set correctly

"Fragment not attached to context"

• Use getViewLifecycleOwner() not getLifecycleOwner()
• Check fragment is still attached before operations

"ANR (Application Not Responding)"

• Move heavy operations to background thread
• Use coroutines properly
• Profile with Android Profiler

Useful Commands

# Build debug APK
./gradlew assembleDebug

# Build release bundle
./gradlew bundleRelease

# Run tests
./gradlew test

# Run instrumentation tests
./gradlew connectedAndroidTest

# Check lint
./gradlew lint

# Profile app
./gradlew profileRelease

Resources

Official Docs:

• Android Developer Docs
• Kotlin Documentation
• Jetpack Guide

Training:

• Google Codelabs
• Android Developers Blog

Tools:

• Android Studio
• Android Profiler
• Firebase Test Lab

Quick Checklist

Before launching to Play Store:

• ✅ App runs without crashes
• ✅ All tests passing
• ✅ No memory leaks
• ✅ 60+ FPS rendering
• ✅ Fast startup (< 5 seconds)
• ✅ Security reviewed
• ✅ Code obfuscated
• ✅ Signed with production key
• ✅ Version code incremented
• ✅ Crash reporting configured

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Need more detailed help?

• /dev-guide - Complete development guide
• /code-examples - Real-world code examples
• Use agents for specific topics: kotlin-essentials, android-core, jetpack-modern, architecture-solid