How to check a nullable boolean in kotlin

Question

if I want to check a nullable Boolean I get a type mismatch

var bool: Boolean? = true

if(bool) 
  println("foo") 
else 
  println("bar")

because Boolean is expected not Boolean?

Answer 1

If you want to treat null case differently from either true or false:

when(bool) {
    null -> println("null")
    true -> println("foo")
    false -> println("bar")
}