How to call list passed as argument in Scala

Question

I am trying to do the following...

I have a class defined as RefInt and a method refInt5 which should take a List of references to instances of RefInt.

I need to change the argument in such a way so that it becomes visible to the caller.

object argpass {

  class RefInt (initial : Int) {
    private var n : Int = initial 
    def get () : Int = n 
    def set (m : Int) : Unit = { n = m }
  }

  def refint5 (xs : List[RefInt]) : Unit = {

    // What am I missing to modify RefInt(s)?

  }
}

The test code I have to see if the argument has changed.

property ("EX05 - refint5", EX (5)) {
    val rand = scala.util.Random
    val xs : List[Int] = (1 to 5).toList.map (x => rand.nextInt (100))
    val ys : List[RefInt] = xs.map (x => new RefInt (x))
    refint5 (ys)
    var changed = false
    for ((x, r) <- xs.zip (ys)) {
      if (x != r.get) {
        changed = true
      }
    }
    if (!changed) {
      throw new RuntimeException ("xs is unchanged!")
    }
  }
}

Answer 1

One possible option: Iterate xs, call set for each element - get the current value - add 1.

def refint5(xs: List[RefInt]): Unit = {
  xs.foreach { x => x.set(x.get + 1) }
}