How to get trait's extended superclass/trait in Scala

Question

I am trying to answer practice question from Book "Scala for Impatient 2nd Edition". The question is like this :

Look at the BitSet class, and make a diagram of all its superclasses and traits.Ignore the type parameters (everything inside the […]).Then give the linearization of the traits.

The first impression I am thinking of is to get all BitSet 's superclasses/traits in a List.

To recursively get superclasses for a given class, I am managing to use below snippet

  def recurGetSupers(cls: Class[_]): List[Class[_]] = {
        cls :: Option(cls.getSuperclass).map(recurGetSupers).getOrElse(Nil)
  }

However, using above snippet will not give me a List of class, as expected, but below :

scala> recurGetSupers(classOf[scala.collection.BitSet])
res0: List[Class[_]] = List(interface scala.collection.BitSet)

So, my question is how to get superclasses or trait for the given trait ?

Answer 1

Scala traits correspond to Java interfaces. So to get them you need the getInterfaces method. In Scala terms, it returns an Array[Class[_]] which will get implicitly converted to a Seq and you can call toList on it.