in scala
class Null

final abstract class Null
extends java.lang.Object

Class Null (previously named AllRef in Scala 2.2.0 and older versions) is - together with class Nothing - at the bottom of the Scala type hierarchy.

Type Null is a subtype of all reference types; its only instance is the null reference. Since Null is not a subtype of value types, null is not a member of any such type. For instance, it is not possible to assign null to a variable of type Int.