Kotlin interviews—especially Android and JVM backend—cover null safety, data classes, coroutines, collections, generics variance, Java interop, and how Kotlin compares to Java, Go, and C#.
Must-know topics
val/var, null safety,data class,sealed class,object- Extension functions, lambdas, inline/reified generics
- Coroutines: suspend, scope, dispatchers, Flow basics
- Collections immutability,
map/filter, sequences vs lists - Java interop: platform types, @JvmStatic, SAM
Important interview questions and answers
- Q: Explain null safety in Kotlin.
A: Types are non-null by default;?marks nullable types; safe calls and Elvis avoid NPEs; platform types from Java need explicit handling. - Q: When choose coroutines over threads?
A: Many concurrent I/O tasks with structured cancellation—lighter than one thread per task; use threads for CPU-bound pools with clear sizing.
Self-check
- List three Kotlin topics you will review before interviews.
- How does Kotlin concurrency differ from Go goroutines?
Tip: Be ready to explain inline reified, coroutine scopes, and why Kotlin beats Java boilerplate on Android.
Interview prep
- Top interview topics?
Null safety, data classes, coroutines, inline/reified, Java interop, variance.
- Kotlin vs Java syntax win?
Data classes, properties, when, extensions, and null types.