Kotlin and Java Interoperability Questions

Practical mastery of Kotlin language features and how they interoperate with Java code bases. Topics include null safety and platform types, extension functions, data classes, sealed classes, higher order functions and idiomatic Kotlin patterns, plus interoperability concerns such as calling Kotlin from Java and Java from Kotlin, nullability annotations, JVM annotations and compiled signatures, collection type differences, handling checked exceptions and migration strategies for mixed code bases. Candidates should be prepared to explain when Kotlin features improve expressiveness and maintainability and how to integrate Kotlin into legacy Java projects while preserving binary compatibility and minimizing runtime surprises.