Kotlin-Annotation-Hello-World.kt

import kotlin.reflect.full.findAnnotation

annotation class HelloName(val name: String)

abstract class Hello {
    fun getName(): String {
        val ann = javaClass.kotlin.findAnnotation<HelloName>()
        return ann?.name ?: throw IllegalStateException("Missing annotation @HelloName")
    }
}

@HelloName("World")
class Learn : Hello()

fun main(args: Array<String>) {
    println("Hello ${Learn().getName()}")
}