Scala: generics, primitive types and nulls

1 min read
Apr 25, 2018

While working on a Scala (2.12.4) project, I made a typo in my code and received an interesting output:

scala> new Get[Int]().inner() == null <console>:13: warning: comparing values of types Int and Null using `==' will always yield false new Get[Int]().inner() == null ^ res0: Boolean = true 

While it was an absolutely useless construction, it still causes such misleading output as seen above:

class Get[T]() { val x: T = inner() def inner(): T = x } new Get[Int]().inner() == null 

I would say that this is a minor Scala bug and probably is a side effect of some of value type + null bugs and other bugs, bugs.

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