Covariance (`out`) vs Contravariance (`in`)? - Android Interview Questions | Android Engineers

🚀 Enrollments Open for Jetpack Compose Cohort 3 — 4 Weeks of Live Learning to Build Modern Android UIs 💚Join Now

Questions

•Builder Pattern in Kotlin?•Collections API in Kotlin?•Covariance in Kotlin?•Delay vs Thread.sleep?•Difference Between const val and val?•Difference between Coroutine and Java Thread?•Difference between Flow/SharedFlow/StateFlow and elaborate it.•Dispatchers.Default vs Dispatchers.IO?•Exception Handling in Coroutine?•Higher Order Functions in Kotlin?•How does Coroutine switch context?•How to choose between apply and with?•How to manage series and parallel execution?•Is singleton thread-safe? vs Object?•Map vs FlatMap in Kotlin?•On which thread does Dispatchers.Default execute the task or use which thread?•Singleton Pattern in Kotlin with object keyword?•StateFlow vs SharedFlow?•Suspending vs Blocking in Kotlin Coroutines?•What are Dispatchers and name all of them?•What are the different Coroutine Scopes?•What happens if we call .cancel() from a coroutine scope?•What is an Init block in Kotlin?•What is Data Class in Kotlin?•What is inline function in Kotlin?•What is SupervisorScope?•What is Unidirectional Flow?•When to use Kotlin sealed classes?•Why Coroutines are lightweight?•What is Coroutine Context?•How to choose between apply and with??•Open keyword in Kotlin?•Is it possible to force the Garbage Collection in Android??•let scope function and its use cases?•What is the difference between open and public in Kotlin??•Launch vs Async in Kotlin Coroutines?•Why do we need to call setContentView() in onCreate() of Activity class?•What is Coroutine Scope??•What is a ViewModel and how is it useful??•Write a function(Higher-Order Function) that returns a function.?•What are Labels in Kotlin?•Android Push Notification Flow using FCM?•How does the Kotlin Multiplatform work?•What is a JvmStatic Annotation in Kotlin?•JvmOverloads Annotation in Kotlin?•What is the equivalent of Java static methods in Kotlin??•What is an inline function in Kotlin?•Difference between List and Array types in Kotlin?•What is Coroutine Context??•`inline` vs `noinline` vs `crossinline`?•`launch` vs `async` in Coroutines?•`lateinit` vs `lazy` initialization?•What are Data Classes and their requirements?•Sealed Class vs Enum?•How do Extension Functions work under the hood?•Scope functions: `apply` vs `also` vs `run` vs `let` vs `with`?•`companion object` vs `object`?•Usage of `@JvmStatic` annotation?•Delegated Properties and the `by` keyword?•Reified types in inline functions?▶Covariance (`out`) vs Contravariance (`in`)?•`viewModelScope` vs `lifecycleScope`?•`flowOn` vs `subscribeOn` (threading)?•Cold Flow vs Hot Flow (StateFlow/SharedFlow)?•Exception handling nuances in `launch` vs `async`?•Usage of `yield()` in Coroutines?•What is `Nothing` type and its potential uses?•Difference between `Unit` and `Void`?•When and how to use `typealias`?•Explain Operator Overloading in Kotlin?•How do Destructuring Declarations work?•What is the purpose of the `tailrec` modifier?•What are SAM (Single Abstract Method) conversions?•`@Volatile` vs `@Synchronized` annotations?•`Sequence` vs `Iterable`: Lazy vs Eager evaluation?•What is the Contract API in Kotlin?

KotlinAdvanced5 min

Covariance (`out`) vs Contravariance (`in`)?

Want to master these concepts?

Join our live cohorts and build production-ready Android apps.

Previous Question

Reified types in inline functions?

Activity Lifecycle: A starts B, what happens to A?

1:1 Mentorship

Get personalized guidance from a Google Developer Expert. Accelerate your career with dedicated support.

Personalized Learning Path

Mock Interviews & Feedback

Resume & Career Guidance

Limited slots available each month

Share & Help Others

Help fellow developers prepare for interviews

Sharing helps the Android community grow 💚

Related Questions

Builder Pattern in Kotlin?

KotlinIntermediate

Collections API in Kotlin?

KotlinIntermediate

Covariance in Kotlin?

KotlinIntermediate

Delay vs Thread.sleep?

KotlinIntermediate

Difference Between const val and val?

KotlinIntermediate