Utilisé surtout pour convertir des Listes. coté java 
public class Toto {
    private String name;
...
    public List getFriends() {
        return Arrays.asList("Alice", "Wendy");
    }
}
coté scala 
import scala.collection.JavaConverters._

class Hello {

  def affiche(l: Toto) = {
    l.getFriends.asScala.toList.foreach({
      x =>
        x match {
          case "Wendy" => println("Whouahou is Wendy")
          case s: String => println("friends is " + s)
        }
    })

  }
}