Android + Kotlin Interview Questions (2026) – Most Asked & Explained

Practical • Scenario-Based • Production-Focused

Why Interviewers Combine Android + Kotlin

🔸 Kotlin is the official Android language
🔸 Tests real-world development skills
🔸 Evaluates architecture + language knowledge
🔸 Differentiates tutorial learners from experienced developers

CORE ANDROID + KOTLIN QUESTIONS

1. Why is Kotlin preferred for Android development?

🔸 Null safety reduces crashes
🔸 Less boilerplate than Java
🔸 Better readability and maintainability
🔸 Full Java interoperability

2. How does Kotlin null safety help in Android apps?

🔸 Prevents NullPointerException
🔸 Forces compile-time checks
🔸 Safer UI and lifecycle handling

3. How do you handle null values in Android UI code?

🔸 Safe call operator (?.)
🔸 Elvis operator (?:)
🔸 ViewBinding to avoid null views

4. What Kotlin features improve Android performance?

🔸 Data classes
🔸 Inline functions
🔸 Lazy initialization
🔸 Coroutines instead of threads

5. How do coroutines improve Android apps?

🔸 Avoid blocking main thread
🔸 Simplify async code
🔸 Better lifecycle management
🔸 Less memory usage

6. Where do you use coroutines in Android?

🔸 Network API calls
🔸 Database operations
🔸 Background tasks
🔸 UI state updates

7. Difference between launch and async in Android usage

🔸 launch – Fire and forget (UI events)
🔸 async – Returns result (API calls)

8. How do ViewModel and Coroutines work together?

🔸 ViewModelScope manages lifecycle
🔸 Prevents memory leaks
🔸 Cancels coroutines automatically

9. Why should you not launch coroutines in Activity?

🔸 Activity lifecycle is short
🔸 Risk of memory leaks
🔸 ViewModelScope is safer

10. How does Kotlin Flow help in Android?

🔸 Handles async data streams
🔸 Lifecycle-aware collection
🔸 Ideal for UI state updates

ARCHITECTURE + KOTLIN QUESTIONS (VERY COMMON)

11. How does MVVM work with Kotlin?

🔸 View – Activity / Fragment
🔸 ViewModel – Business logic
🔸 Model – Data source
🔸 Kotlin simplifies data handling

12. Why use sealed classes in Android UI state?

🔸 Restricts possible states
🔸 Compile-time safety
🔸 Cleaner UI handling

13. How do you represent UI states in Kotlin?

🔸 Loading
🔸 Success
🔸 Error
🔸 Empty

14. Why is Repository pattern important?

🔸 Single source of truth
🔸 Separates data logic
🔸 Improves testability

15. How do you handle configuration changes using Kotlin?

🔸 ViewModel
🔸 SavedStateHandle
🔸 Avoid Activity-level state

REAL INTERVIEW SCENARIO QUESTIONS

16. App crashes on rotation – how do you fix it?

🔸 Move logic to ViewModel
🔸 Avoid holding Activity reference
🔸 Use ViewBinding

17. API call blocks UI – what’s wrong?

🔸 Network call on Main thread
🔸 Move to IO dispatcher
🔸 Use coroutines

18. RecyclerView scrolling is laggy

🔸 Use DiffUtil
🔸 Avoid heavy operations in onBind
🔸 Optimize layouts

19. Memory leak detected in Fragment

🔸 Clear binding in onDestroyView
🔸 Avoid static context
🔸 Cancel background tasks

20. How do you handle errors in Kotlin + Android?

🔸 Sealed class for UI state
🔸 Centralized error mapper
🔸 Retry mechanisms

ANDROID + KOTLIN BEST PRACTICES

21. How do you avoid memory leaks using Kotlin?

🔸 Use weak references
🔸 Avoid global coroutines
🔸 Use lifecycle-aware scopes

22. Why use ViewBinding with Kotlin?

🔸 Null-safe view access
🔸 No findViewById
🔸 Faster than DataBinding

23. How do you structure large Android projects?

🔸 Feature-based modules
🔸 Clean Architecture
🔸 Shared core module

24. How do you write clean Kotlin code?

🔸 Use immutability
🔸 Avoid nested logic
🔸 Follow naming conventions

25. How do you test Android + Kotlin code?

🔸 Unit tests for ViewModel
🔸 Mock repositories
🔸 Coroutine testing tools

SENIOR-LEVEL ANDROID + KOTLIN QUESTIONS

26. How do you handle backward compatibility?

🔸 AndroidX
🔸 Feature flags
🔸 Kotlin language compatibility

27. How do you improve app startup time?

🔸 Lazy initialization
🔸 Avoid heavy Application.onCreate
🔸 Use SplashScreen API

28. How do you secure data in Kotlin Android apps?

🔸 EncryptedSharedPreferences
🔸 HTTPS
🔸 Certificate pinning

29. How do you manage multi-flavor apps using Kotlin?

🔸 productFlavors
🔸 Environment-based configs
🔸 Different API endpoints

30. What makes a strong Android + Kotlin developer?

🔸 Strong Kotlin fundamentals
🔸 Android lifecycle understanding
🔸 Clean architecture
🔸 Problem-solving skills