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Nothing and Null Types in Scala

Scala Nothing and Null Types: Nothing and null are the value returned when no other value is returned by the program. In this Scala tutorial on nothing and null types we will learn about Scala nothing and null, nill types.
Submitted by Shivang Yadav, on July 22, 2019

Scala Nothing Type

It is a trait in Scala. Being a trait it does not have any instance, and is contained by every data set but is not a superclass. Nothing has found uses in functions that always return an exception to handle.

Scala Nil Type

It is a list that has no element. Nil uses nothing as it is a subset. Nil's type is list[nothing].

    var a = nil gives a lit[nothing]

Scala Null Type

It is a trait that is used only by reference instances, not data instances. This means it is a subset of only reference class. Scala uses Option instead of Null as it is more effective. The value of the reference data types like objects etc is null, but this value is not valid for data types like Int, Float, etc.

Scala None Type

It is the replacement of null in the option type of Scala. It has none that is initialized when no value is given.

Example:

object MyClass {
    
    def main(args: Array[String]) {
        println(null);
        //println(none) // gives error : not found : value none 
        println(Nil)
    }

}

Output

null
List()

Example of None in Scala

object MyClass {
    
    def main(args: Array[String]) {
         //printing empty list
        println(None.toList) 
        //checking whether None is empty or not
        println(None.isEmpty)
        //printing value of None as string
        println(None.toString)
    }

}

Output

List()
true
None