generics - What is out keyword in kotlin

Question

I am not able to understand and I couldn't find the meaning of out keyword in kotlin.

You can check example here:

List<out T>

If any one can explain the meaning of this. It would be really appreciated.

Answer 1

List<out T> is like List<? extends T> in Java

and

List<in T> is like List<? super T> in Java

For example in Kotlin you can do things like

 val value : List<Any> = listOf(1,2,3)
//since List signature is List<out T> in Kotlin