Most Asked Android Interview Questions In 2022

Hey Android Folks,

Hi, I am Rahnuma Sharib, I have mentored many developers, and their efforts landed them high-paying tech jobs, helped many tech companies in solving their unique problems. I am passionate about sharing knowledge through open-source, blogs, and videos.

I habitually note down questions immediately after completing my interview round. I have listed down below some interview questions for senior developers and tried to include answers to most questions as well.

Java

• What is the diff between encapsulation & abstraction give practical example
• HashMaps vs HashTables
• Explain OOP Concepts.
• When to use array & Array List
• What is the volatile keyword
• What is the transient keyword
• What is a diff between a string buffer & string builder
• Why is string immutable
• What is the diff between encapsulation & abstraction (practical example)
• class A -> extends class B, implements interface C. Both have the same method fun add() {}, Which one will be implemented in class A?
  Try yourself
• What is the difference between String test = new String(“X”) & String test = “X”. Explain String constant pool & String literal

Android

• When I am in my activity get a phone call what will be the lifecycle of the activity
• When I am in my activity get a phone call what will be the lifecycle of the fragment inside my activity
• Fragment, activity and application life cycle and when there life cycle method get trigger.
• Difference between fragment or activity
• What is fragment.
• What happen when we press back button on activity A.
• Which activity life cycle method trigger when orientation change.
• When onDistroy will get called before onPause or onStop.
• Type of services in Android
• What do you think about NavHost in navigation
• What are SOLID principles?
• What is broadcast receiver and content provider and how can we implement it.
• Advantage of using recycle view over list and grid view.
• Launch mode and there type and differences.
• Data binding and its type.
• How to pass data from activity to fragment or fragment to fragment.
• Difference between adding or replacing a fragment.
• What is Intent and its type
• Constraint layout and its advantage
• Difference between push value and set value ( Live Data )
• Advantage of using live data
• Dex file
• Which database you use and why
• Benefit of using Room database
• Difference between room and sqlite.
• Difference between service and thread.
• What's is concurrency.
• How to improve app performance
• What is memory leak and how to avoid it
• How to go back on previous fragment when click on back button
• How to communicate between service and activity
• What is concurrency
• On which thread service run and how can we change the thread.
• Job intent service and its purpose
• How to improve application performance.
• What is memory leak and how to solve it.
• How service will communicate with activity.
• What is job scheduler and its work.
• Parameter constructer and non parameter constructer are good and why in fragment.

Kotlin

• What are the benefits of Kotlin over Java
• Explain the use of lateinit & lazy keywords
• How to check lateinit class is initialize or not.
• What is null safety in Kotlin?
• What is the diff between Var & Val and const and val
• What is Elvis operator?
• What is Flow API in Kotlin
• Explain coroutines in kotlin
• What are scoped functions and there use in kotlin
• What is singleton class and how can you declare it?
• what is the diff between companion obj & object
• Used extension functions? example
• Data class and how its different from other classes.
• Sealed class.
• What is suspend function.
• what is the diff between static & singleton Explain @jvmstatic @jvmoverloads @jvmfiled
• Difference between volatile and syncronized.
• Live data, Mutable live data and Mediator live data
• Advantage of live data
• What is flow , state flow and shared flow
• Extension, inline, inflix and high order function and there benefit in term of memory.
• Difference between public ( visiblity modifier ) and open keyword
• Difference between volatile and synchronized.
• Arraymap and hashmap.
• How hashmap work in background.
• What is referential equality and structal equality.
• Will reference of two data class with same set of data will it be equal or not?

Kotlin Coroutines.

• What is coroutines.
• What is coroutines dispatchers there type and work.
• What is coroutines scope and its type.
• What is coroutines context.
• What is coroutines builder, its type and there work.
• Difference between launch and async

ViewModel.

• What is ViewModel and its advantage.
• How to instantiate viewmodel.
• What is the difference between ViewModel and AndroidViewModel.
• How ViewModel work internally.
• How ViewModel retain data during configuration change.
• During configuration change activity distroy and re-create then how view-model instance remain same.
• What is view-model factory & how to pass data in view model constructor
• Difference between shared view model and view model.

Dependency Injection.

• What is Dependency Injection and its benefit.
• Where should we write code of DI.
• How hilt provide required object should we write it.

Mvvm

• What is MVVM, and how does it work and its advantage.
• what is the diff between MVP/MVC & MVVM

Networking libraries ( Retrofit & Volley )

• Which one you prefer to use and why?
• advantage of using retrofit.

VCS ( Git)

• what is Marge and rebase in git.
• how you create branch and work on them .

Jetpack Compose

• What are the benefits of using Jetpack compose?
• What is a Composable function?
• What is a declarative approach?
• What jetpack compose libraries have you used?
• Explain compose UI basic components

Testing

• In Unit testing, what is @Before & @Beforeclass annotation used for
• Why should we use a Mockito lib?
• Explain Unit & Instrumentation tests

Data Structure

• What is Queue, Stack and Array.
• The time complexity of Hash Table — O(1)
• Best for getting the last item — Stack
• Time Complexity of Binary Search — O(log N)
• Which is best Sorting Algo — Quick Sort
• Best performance for finding minimum value — Array

That’s a wrap for now! Many more to come
I hope you find this blog helpful.