Convert List[List[Any]] into List[List[String]] in Scala -


i have following list[list[any]] want convert list[list[string]].

val input:list[list[any]] = list(list(1234), list(234, 678), list(8765, 90876, 1))

i looking following output:

val output:list[list[string]] = list(list(1234), list(234, 678), list(8765, 90876, 1))

i have tried doing following:

val output:list[list[string]] = input.map(_.tostring).tolist // or  val output:list[list[string]] = input.map(_.tostring)

none of above give me desired output.

because, list nested, need map twice.

why below not working?

val output:list[list[string]] = input.map(_.tostring)

because, _ placeholder holds value of type list[string] , applying tostring method convert list string , hence result of type list[string] instead of list[list[string]].

scala> input.map(_.tostring) res2: list[string] = list(list(1234), list(234, 678), list(8765, 90876, 1))

therefore, need map input twice. 

scala> input.map(_.map(_.tostring)) res0: list[list[string]] = list(list(1234), list(234, 678), list(8765, 90876, 1))

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