How to iterate over class hierarchy?

Question

I want to iterate over class hierarchy and print all super classes:

open class A {}
open class B : A() {}
open class C : B() {}

fun main(args: Array<String>) {
    var currentClass = C::class
    while(currentClass != Any::class) {
        println(currentClass)
        currentClass = currentClass.superclass
    }
}

but Kotlin KClass doesn't have superclass method.

I have tried to use superclass from Java:

 currentClass = currentClass.java.superclass.kotlin

but it cause compilation error:

Error:(9, 52) Type inference failed: 'T' cannot capture 'in ('C'..'C?')'. 
Type parameter has an upper bound 'kotlin.Any' that cannot be satisfied 
capturing 'in' projection

So, can anybody explain me how to do it?

Answer 1

First, specify explicit type for var currentClass to avoid its inference as KClass<C>:

var currentClass: KClass<*> = C::class

Then, superclass call will return a type with in projection, and you won't be able to call .kotlin on it. So a cast to star-projected type will also help:

currentClass = (currentClass.java.superclass as Class<*>).kotlin

Complete method:

fun main(args: Array<String>) {
    var currentClass: KClass<*> = C::class
    while (currentClass != Any::class) {
        println(currentClass)
        currentClass = (currentClass.java.superclass as Class<*>).kotlin
    }
}