Scala Option(null) expected as None but I got Some(0)

Question

val i: java.lang.Integer = null
val o: Option[Int] = Option(i) // This yields Some(0)

What is the safe wa

Answer 1

You are mixing Int and java.lang.Integer so

val i: java.lang.Integer = null
val o: Option[Int] = Option(i)

implicitly converts to

val o: Option[Int] = Option(Integer2int(i))

which becomes

val o: Option[Int] = Option(null.asInstanceOf[Int])

thus

val o: Option[Int] = Some(0)

If you want to work with java.lang.Integer, then write

val o: Option[java.lang.Integer] = Option(i)
// o: Option[Integer] = None