Null is - together withscala.Nothing - at the bottom of the Scala type hierarchy.

Null is the type of thenull literal. It is a subtype of every type except those of value classes. Value classes are subclasses ofAnyVal, which includes primitive types such asInt,Boolean, and user-defined value classes.

SinceNull is not a subtype of value types,null is not a member of any such type. For instance, it is not possible to assignnull to a variable of typescala.Int.