Kotlin

publishedBy Jetbrains

Features

compatibility with Java
- "Kotlin seamlessly interacts with Java classes and methods, and vice versa, allowing for a smooth transition to the new language without the need to rewrite existing code."
extensions allow adding new functions to existing classes without modifying them

Coroutines

"2. Conceptually Coroutines are very similar to VirtualThreads. The identical parts are: lightweight threads and structured concurrency. But there are also some differences:
- Coroutines are more feature rich than what Loom offers now, namely:
  - context propagation (meaning let the same context, like a MDC, Transaction etc. be propagated across several Coroutines) is fully embedded in Coroutines. Loom is still experimenting with this part, which they call scope variables.
  - Cancellation: Part of the Contract Coroutines offer is cancellation, no matter how nested a process tree might be. This is and will not be available in Loom. In certain use-cases this is a big omission for Loom."1

Nullable Types

In Java, you need to explicitly check for null before accessing an object to avoid NullPointerException. This often leads to verbose null-checking code.

val name: String? = null
println(name?.length ?: "Name is null")

Kotlin uses the safe call operator (?.) and the Elvis operator (?:) to handle nullables concisely. This line safely accesses the length if name is not null, or otherwise prints "Name is null". In Kotlin, the safe call operator, ?., and the ?: operator are used for default values, simplifying null handling.