Checking for null

Check for null as a condition in the if block:

fun main(args: Array<String>) {
    val nullableCupcake: Cupcake? = Cupcake.almond()

    if (nullableCupcake != null) {
      nullableCupcake.eat()
    }
}

Kotlin will do a smart cast. Inside the if block, nullableCupcake is a Cupcake, not a Cupcake?; so, any method or property can be accessed.