default.scala

class Something{
  var x: Double = _
  var y: String = _
  var z: Char = _
}

val s = new Something
s.x
s.y
s.z

//=================
scala> val s = new Something
s: Something = Something@74093613

scala> s.x
res7: Double = 0.0

scala> s.y
res8: String = null

scala> s.z
res9: Char = ?