71 Android interview questions with answers

All Android interview questions

• What is the difference between `val` and `var` in Kotlin?

• Explain Kotlin null safety and the difference between nullable and non-nullable types.

• What are extension functions in Kotlin and how do they work?

• What is a data class in Kotlin and what does it auto-generate?

• Explain sealed classes and their use case in Android.

• What are scope functions (let, run, apply, also, with) and when to use each?

• What are coroutines and why are they better than callbacks?

• Explain the difference between `launch` and `async` in Kotlin coroutines.

• What are suspend functions in Kotlin?

• How does Kotlin handle exception handling in coroutines?

• What is a companion object in Kotlin?

• Explain destructuring in Kotlin.

• Explain the Android Activity lifecycle and each method's purpose.

• What is the difference between `replace()` and `add()` in Fragment transactions?

• What are Intents in Android and what are the two types?

• What is a Service in Android and when should you use it?

• What are BroadcastReceivers and how do they work?

• What is ContentProvider and its use case?

• What are the different Android permission types and how do you handle runtime permissions?

• What is the difference between savedInstanceState and onSaveInstanceState()?

• Explain Intent filters and implicit intents.

• What are the differences between Process and Thread in Android?

• What is Jetpack Compose and why is it replacing XML layouts?

• What is a Composable function and what makes something Composable?

• Explain state management in Jetpack Compose using `mutableStateOf` and `remember`.

• What is the difference between `remember` and `rememberSaveable`?

• Explain state hoisting in Jetpack Compose and why it's important.

• What is `LaunchedEffect` and when should you use it?

• Explain the difference between `LaunchedEffect`, `DisposableEffect`, and `SideEffect`.

• What is a Modifier in Jetpack Compose and give examples.

• How do you handle navigation in Jetpack Compose?

• What is `derivedStateOf` and when should you use it?

• How do you implement theming in Jetpack Compose?

• What are CompositionLocals and how do they work?

• What is MVVM architecture and how is it structured?

• What is MVI architecture and how does it differ from MVVM?

• What is the Repository pattern and why is it important?

• Explain the difference between LiveData and StateFlow.

• What is a ViewModel and why should you use it?

• What is dependency injection and why is it important in Android?

• What is Hilt and how does it simplify dependency injection?

• Explain Clean Architecture and its layers.

• What is the Use Case pattern and when should you create one?

• What are the different Hilt scopes and what do they mean?

• What is Room database and why use it instead of SQLite directly?

• What is a DAO (Data Access Object) in Room?

• What is Retrofit and how does it work?

• What are Interceptors in Retrofit/OkHttp and how do you use them?

• How do you implement authentication with Retrofit?

• What is DataStore and how does it differ from SharedPreferences?

• What is WorkManager and when should you use it?

• What is the Paging 3 library and why use it?

• What is ProGuard and R8, and how do they optimize apps?

• What are App Bundles and how do they reduce app size?

• What are dynamic feature modules and when should you use them?

• How do you optimize app performance and what are the key metrics?

• What is testing in Jetpack Compose and how does it differ from Espresso?

• What is Kotlin Multiplatform (KMP) and how does it relate to Android?

• Explain instrumentation testing and unit testing, and when to use each.

• What are the best practices for memory management in Android?

• How do you implement CI/CD for Android apps?

• What is certificate pinning and how do you implement it?

• What is the Observer pattern and how is it used in Android?

• How do you handle configuration changes (like screen rotation)?

• What is the difference between hot and cold flows?

• What is `Context` in Android? Contrast Application context vs Activity context (memory-leak angle).

• What is an ANR (Application Not Responding) and how do you prevent it?

• What is `RecyclerView` and how does its view-recycling mechanism work?

• What is Gradle and what role does it play in building an Android app?

• What are inline functions in Kotlin? Explain `inline`, `noinline`, and `reified`.

• Distinguish cold / warm / hot start and how to optimize app startup time.