Question

I have been always using

a != null

to check that a is not a null reference. But now I’ve met another way used:

a.ne(null)

what way is better and how are they different?

Answer 1

Like @Jack said x ne null is equal to !(x eq null). The difference between x != null and x ne null is that != checks for value equality and ne checks for reference equality.

Example:

scala> case class Foo(x: Int)
defined class Foo

scala> Foo(2) != Foo(2)
res0: Boolean = false

scala> Foo(2) ne Foo(2)
res1: Boolean = true