无法将List [Any]转换为List [（String，String）]

Question

I have a Scala List

freq_items_list
List[Any] = List(Array((fid,1007)), Array((tes,d0920)), Array((tn,r3026), (fd,1007)), Array((tn,g5260_p2)), Array((testN
ame,g5260_p2), (fd,1007)), Array((tn,c7835)), Array((tn,g5250_p2)), Array((tn,g5250_p2), (fd,1007)), Array((tn,r7090)),
Array((tn,r7090), (fd,1007)))

I try converting it to List[(String,String)] by using

frequent_items_list.map(_.asInstanceOf[Array[(String, String)]])

However when I try that I get a ClassCastException

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Lscala.Tuple2;

I am new to Scala is there another way to convert this and what is wrong with the current way?

Answer 1

This will get you a List[(String, String)] result even if the tuple elements are not strings (they can even be a mix of types), but it will drop any List element that is not an Array() and it will drop any Array elements that aren't 2-tuples.

freq_items_list.flatMap{case a:Array[_]=> a.toList; case _ => List()}
               .collect{case (x,y) => (x.toString, y.toString)}