Kotlin wildcards for variables

Question

Is it possible to declare common wildcards in Kotlin, like this code in Java:

List<Integer> a = new ArrayList<>(); List<? extends Number> b = a; 

Answer 1

The equivalent in Kotlin would be:

 val a = ArrayList<Int>() val b: ArrayList<out Number> = a 

Answer 2

Kotlin does not have wildcards; instead, it uses the concepts of deviation from declarations and types.

Please review the documentation, which covers quite extensively.

Kotlin provides so-called stellar projection

 val a = ArrayList<Int>() val b: ArrayList<out Number> = a