Mock interviews

How a mock works

1. TimedAbout 3 minutes a question, with a visible clock you can pause.
2. Out loudAnswer as you would in the room. Nothing is recorded.
3. Follow-upsThen the follow-up questions an interviewer would ask.
4. RubricTick the key points you covered; that is your score.

Mock sets (34)

• Coroutines mock 1

  Coroutines · 5 questions · about 25 min

  • What happens to viewModelScope work on rotation?
  • Structured concurrency
  • CoroutineScope vs CoroutineContext
  • withContext and main-safety
  • Cooperative cancellation

  Start this mock on the Coroutines page

• Coroutines mock 2

  Coroutines · 5 questions · about 25 min

  • Don't swallow CancellationException
  • Loading several things in parallel
  • Shared mutable state
  • Collecting safely from the UI
  • Why not GlobalScope?

  Start this mock on the Coroutines page

• Coroutines mock 3

  Coroutines · 5 questions · about 25 min

  • runBlocking on Android
  • Job vs SupervisorJob
  • Where CoroutineExceptionHandler works
  • Coroutines vs threads
  • What does suspend mean?

  Start this mock on the Coroutines page

• Flow and StateFlow mock 1

  Flow and StateFlow · 5 questions · about 25 min

  • StateFlow vs SharedFlow
  • stateIn and WhileSubscribed(5_000)
  • Search-as-you-type with Flow
  • combine vs zip
  • Handling errors in a Flow

  Start this mock on the Flow and StateFlow page

• Flow and StateFlow mock 2

  Flow and StateFlow · 5 questions · about 25 min

  • Wrapping a listener with callbackFlow
  • Why didn't my StateFlow update?
  • One-off events from a ViewModel
  • flowOn and context preservation
  • buffer, conflate and collectLatest

  Start this mock on the Flow and StateFlow page

• Jetpack Compose mock 1

  Jetpack Compose · 5 questions · about 25 min

  • What triggers recomposition?
  • derivedStateOf
  • LaunchedEffect and its keys
  • DisposableEffect
  • Keys in LazyColumn

  Start this mock on the Jetpack Compose page

• Jetpack Compose mock 2

  Jetpack Compose · 5 questions · about 25 min

  • CompositionLocal
  • Navigation in Compose
  • Slot APIs
  • Compose and Views together
  • Stability and skipping

  Start this mock on the Jetpack Compose page

• Jetpack Compose mock 3

  Jetpack Compose · 5 questions · about 25 min

  • Deferring state reads
  • rememberUpdatedState
  • Strong skipping mode
  • Compose vs the View system
  • remember vs rememberSaveable

  Start this mock on the Jetpack Compose page

• Jetpack Compose mock 4

  Jetpack Compose · 5 questions · about 25 min

  • State hoisting
  • rememberCoroutineScope
  • Why modifier order matters
  • collectAsStateWithLifecycle
  • Previews that scale

  Start this mock on the Jetpack Compose page

• Lifecycle and app components mock 1

  Lifecycle and app components · 5 questions · about 25 min

  • Lifecycle order: A opens B
  • SavedStateHandle
  • Fragment and view lifecycles
  • How a ViewModel survives
  • Launch modes and tasks

  Start this mock on the Lifecycle and app components page

• Lifecycle and app components mock 2

  Lifecycle and app components · 5 questions · about 25 min

  • PendingIntent and mutability
  • Services and foreground service types
  • Broadcast receivers
  • Content providers
  • Application class and startup work

  Start this mock on the Lifecycle and app components page

• Lifecycle and app components mock 3

  Lifecycle and app components · 5 questions · about 25 min

  • TransactionTooLargeException
  • Process death
  • The Activity lifecycle
  • Configuration changes
  • Explicit and implicit intents

  Start this mock on the Lifecycle and app components page

• Kotlin language mock 1

  Kotlin language · 5 questions · about 25 min

  • Sealed classes and exhaustive when
  • Extension functions
  • Delegation with by
  • Smart casts and their limits
  • Value classes

  Start this mock on the Kotlin language page

• Kotlin language mock 2

  Kotlin language · 5 questions · about 25 min

  • Collections vs sequences
  • Kotlin 2 and the K2 compiler
  • @JvmStatic, @JvmField and @JvmOverloads
  • inline functions and reified
  • Generics: in, out and star projection

  Start this mock on the Kotlin language page

• Kotlin language mock 3

  Kotlin language · 5 questions · about 25 min

  • How Kotlin code runs on Android
  • Null safety and !!
  • val, var and const val
  • Data classes
  • == vs ===

  Start this mock on the Kotlin language page

• Kotlin language mock 4

  Kotlin language · 5 questions · about 25 min

  • let, run, with, apply, also
  • lateinit vs by lazy
  • Lambdas, function types and fun interfaces
  • object, companion object and singletons
  • Visibility: internal and friends

  Start this mock on the Kotlin language page

• Views, layouts and RecyclerView mock 1

  Views, layouts and RecyclerView · 5 questions · about 25 min

  • How a View is measured, laid out and drawn
  • RecyclerView, ListAdapter and DiffUtil
  • Writing a custom View
  • Large screens and window size classes
  • Touch event dispatch

  Start this mock on the Views, layouts and RecyclerView page

• Architecture and dependency injection mock 1

  Architecture and dependency injection · 5 questions · about 25 min

  • UI, domain and data layers
  • Unidirectional data flow and UiState
  • MVVM vs MVI
  • Repositories and a single source of truth
  • Use cases and the domain layer

  Start this mock on the Architecture and dependency injection page

• Architecture and dependency injection mock 2

  Architecture and dependency injection · 5 questions · about 25 min

  • Hilt basics
  • Modelling errors
  • SOLID on Android
  • Hilt vs Koin vs manual DI
  • Hilt components and scopes

  Start this mock on the Architecture and dependency injection page

• Architecture and dependency injection mock 3

  Architecture and dependency injection · 5 questions · about 25 min

  • Runtime arguments with Hilt
  • Modularisation
  • Navigation between feature modules
  • Dependency injection
  • Design patterns you use every day

  Start this mock on the Architecture and dependency injection page

• Data and storage mock 1

  Data and storage · 5 questions · about 25 min

  • How Room Flow queries update
  • Relations, transactions and N+1 queries
  • Room migrations
  • Scoped storage
  • Paging 3

  Start this mock on the Data and storage page

• Data and storage mock 2

  Data and storage · 5 questions · about 25 min

  • Cache freshness and stale data
  • What to clear on logout
  • Database performance
  • Room basics
  • DataStore vs SharedPreferences

  Start this mock on the Data and storage page

• Background work and notifications mock 1

  Background work and notifications · 5 questions · about 25 min

  • Chaining work and constraints
  • Doze and App Standby
  • Exact alarms
  • Push messages with FCM
  • Expedited and long-running work

  Start this mock on the Background work and notifications page

• Networking mock 1

  Networking · 5 questions · about 25 min

  • OkHttp interceptors
  • kotlinx.serialization vs Gson
  • Retries with exponential backoff
  • HTTP caching with OkHttp
  • Handling offline and flaky networks

  Start this mock on the Networking page

• Performance mock 1

  Performance · 5 questions · about 25 min

  • Looper, Handler and the main thread
  • ANRs: causes and fixes
  • Jank and dropped frames
  • Memory leaks
  • Cold start time

  Start this mock on the Performance page

• Performance mock 2

  Performance · 5 questions · about 25 min

  • Smooth long lists
  • Profiling tools
  • Macrobenchmark and Microbenchmark
  • Battery-friendly apps
  • Baseline Profiles

  Start this mock on the Performance page

• Testing mock 1

  Testing · 5 questions · about 25 min

  • Testing coroutines with runTest
  • Testing Flows
  • Testing a ViewModel
  • Compose UI tests
  • Screenshot tests

  Start this mock on the Testing page

• Security mock 1

  Security · 5 questions · about 25 min

  • Storing tokens and secrets on device
  • Android Keystore
  • Biometric authentication
  • Network security config and pinning
  • Exported components and intent safety

  Start this mock on the Security page

• Runtime, build and Gradle mock 1

  Runtime, build and Gradle · 5 questions · about 25 min

  • ART: interpreter, JIT and AOT
  • R8, shrinking and keep rules
  • kapt vs KSP
  • Speeding up Gradle builds
  • Version catalogs and convention plugins

  Start this mock on the Runtime, build and Gradle page

• Runtime, build and Gradle mock 2

  Runtime, build and Gradle · 5 questions · about 25 min

  • Garbage collection on Android
  • Threads, @Volatile and synchronized
  • Build types, flavors and variants
  • OOP principles in Kotlin
  • Interface vs abstract class

  Start this mock on the Runtime, build and Gradle page

• Modern Android mock 1

  Modern Android · 5 questions · about 25 min

  • Edge-to-edge and window insets
  • Predictive back
  • Deep links and App Links
  • Accessibility in Compose
  • Passkeys and Credential Manager

  Start this mock on the Modern Android page

• Modern Android mock 2

  Modern Android · 5 questions · about 25 min

  • Home screen widgets with Glance
  • On-device AI features
  • Foldables and large screens
  • Kotlin Multiplatform
  • Target SDK upgrades

  Start this mock on the Modern Android page

• Mobile system design mock 1

  Mobile system design · 5 questions · about 25 min

  • Feature flags and staged rollouts
  • Designing an offline-first app
  • Designing a social feed
  • Designing a chat app
  • Designing an image loading library

  Start this mock on the Mobile system design page

• Mobile system design mock 2

  Mobile system design · 5 questions · about 25 min

  • Designing reliable uploads
  • Handling a crash spike after release
  • Designing subscriptions with Play Billing
  • Designing location tracking
  • Designing an analytics or logging SDK

  Start this mock on the Mobile system design page

Behavioral round