Android Interview Questions

Abhinay Gupta
3 min readJul 15, 2023



  • What is the difference between const val and val?
  • What is so interesting about data class?
  • Is singleton thread-safe? vs Object?
  • What are different type of scope modifiers?
  • What are different Coroutine Scope?
  • How to manage series and parallel execution?
  • Difference between Flow/SharedFlow/StateFlow and elaborate it.
  • What happens if we call .cancel() from a coroutine scope?
  • What is an Init block in Kotlin?
  • How to choose between apply and with?
  • What is inline function in Kotlin?
  • Difference between Coroutine and Java Thread
  • Why Coroutines are light weight?
  • How does Coroutine switch context?
  • How does extension functions work?
  • @JvmStatic , static and Companion object
  • Kotlin vs Java
  • Parcelable vs Serializable


  • How does Garbage collection works?
  • What is a dangling pointer?
  • Elaborate Memory Leak?
  • Explain fragment Lifecycle when it comes to ViewPager and sliding between different fragments.
  • Difference between FragmentStateAdapter and FragmentStatePagerAdapter.
  • Difference between Serializable and Parcelable? What are the disadvantages of Serializable?
  • How you could implement observable SharedPrefs or observable Databases i.e. Observe a certain key/table/query?
  • How does layout inflation work from xml tags to view reference in memory?
  • What is a Thread, Handler, Looper and Message Queue?
  • What are the different methods of concurrency on Android? Can you explain the difference between ExecutorService vs CachedThreadPool vs FixedThreadPool vs AsyncTasks vs HandlerThreads?
  • How does ViewModel instance provided to Activity and Fragment. How does ViewModelProviderStoredecide when to retain the instance?
  • How do you inspect and solve Jank issue? here
  • How does the OutOfMemory happens?
  • How do you find memory leaks in Android applications?
  • What is Doze? What about App Standby?
  • What does setContentView do?
  • Process of creating a custom view
  • Deeplink understanding and architecture
  • Notifications


  • How to keep a video maintain playing state when we rotate screen?
  • How many callbacks in Fragmnets?
  • What could be the reasons when onPause didn't get triggered?
  • What kind of events trigger onPause() to run?
  • In what scenario does the “onDestory” get called directly after “onCreate”?
  • Which callback gets called on Activity when an AlertDialog is shown?
  • What’s the lifecycle in PIP (Picture-in-Picture)?
  • What happens if you rotate the device?
  • Inside a viewpager (Fragment state pager adapter) what will be the lifecycle of the fragments when you swap from tab to another ?
  • Why onActivityCreated is now depreciated in Fragment?
  • Which callback should i use if i want to know when my activity came to foreground?
  • When is onActivityResult called?
  • What does setRetainInstance do and how you can avoid it?
  • What callbacks trigger when a Dialog opens up? Conside both case, dialog attached from same activity/fragment and other activity/fragment.
  • What does launchWhenCreated, launchWhenStarted, and launchWhenResumed functions do?


  • Different type of threads?
  • Difference between different type of thread?
  • Thread <-> Handler <-> looper
  • UI vs Background Thread


  • What is SOLID principles?
  • What is MVVM?
  • Brief about Android Architecture.
  • How ViewModel retains the data in screen orientation?
  • MVVM , MVI, MVC, MVP difference
  • Design Patterns


  • How Glide internally works?
  • Hoe does retrofit workss internally?
  • ViewModel internal working
  • Proguard Working and Use

Common Question

  • String vs StringBuilder
  • == vs .equals?
  • === vs ==?
  • Java OOP concepts
  • val vs const
  • inline keyword
  • lateinit vs lazy
  • fragments & their lifecycle, Activity lifecycle, Views, Layouts