How to change Any to Array in scala?

Question

scala> val arr = Array[Any](Array(1.0, 2.0))
arr: Array[Any] = Array(Array(1.0, 2.0))

scala> arr(0)
res28: Any = Array(1.0, 2.0)

The array arr is fixed. How to change arr(0) to Array[Double] in this situation?

Tim · Accepted Answer · 2018-08-29 07:52:46Z

3

There are three options:

1) Don't cast to Array[Any] in the first place:

val arr: Array[Array[Double]] = Array(Array(1.0, 2.0))
val arr0: Array[Double] = arr(0)

2) Use match:

val arr0: Array[Double] = arr(0) match {
  case a: Array[Double] => a
}

3) Use asInstanceOf:

val arr0: Array[Double] = arr(0).asInstanceOf[Array[Double]]

These are in order of preference, with the option 1 being by far the best solution because it avoids throwing away type information.

answered Aug 29, 2018 at 7:52

Tim

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1 Comment

I'd prefer 3 to 2 (with the caveat that they are both bad); 2 is just pointlessly longer and less efficient.