Use a object before initialized as other object argument I'm new to kotlin and I know that nullable are something I should'nt use as much as I would want too. So I was wondering if something like that would be possible. class Header(var next: Trailer) class Trailer(var prev: Header) fun main() { lateinit var trailer: Trailer val header = Header(trailer) trailer = Trailer(header) } Thank you for the time used to answer my question!