Scala worksheet can not resolve class name - IntelliJ IDEA

Question

I am following along with a lecture, the lecturer is using Eclipse but I am using IntelliJ IDEA Community Edition 15.0.6, and the code on a Scala worksheet named rationals.scala is as follows

object rationals{
  val x = new Rational(1,2)
  x.numer
  x.denom
}

//noinspection ScalaPackageName
class Rational(x: Int, y: Int) {
  def numer = x
  def denom = y
}

The Scala worksheet worksheet will not compute and there is a warning (not error) associated with the class definition that reads

Package names doesn't correspond to directories structure, this may cause problems with resolve to classes from this file

Also, and this is odd but maybe significant, IDEA flags numer and denom as typos.

Any guidance? thx

Answer 1

The problem isn't with the name matching directory structure, the actual problem is that you have multiple definitions in the worksheet which it doesn't like. If you declare the class inside the object, then it'll compute properly:

object rationals {
  class Rational(x: Int, y: Int) {
    def numer = x
    def denom = y
  }

  val x = new Rational(1,2)
  x.numer
  x.denom
}

Answer 2

@Yuval Itzchakov @MaxWen

If you reference Rational.scala outside the worksheet, then you have to make sure to tick the Make project box the first time you run it.

Eclipse and IntelliJ worksheets don't work the same. –