Question

It seems like the support for printing arrays is somewhat lacking in Scala. If you print one, you get the default garbage you’d get in Java:

scala> val array = Array.fill(2,2)(0)             
array: Array[Array[Int]] = Array(Array(0, 0), Array(0, 0))

scala> println(array)
[[I@d2f01d

Furthermore, you cannot use the Java toString/deepToString methods from the java.util.Arrays class: (or at least I cannot figure it out)

scala> println(java.util.Arrays.deepToString(array))
<console>:7: error: type mismatch;
 found   : Array[Array[Int]]
 required: Array[java.lang.Object]
       println(java.util.Arrays.deepToString(array))

The best solution I could find for printing a 2D array is to do the following:

scala> println(array.map(_.mkString(" ")).mkString("\n"))
0 0
0 0

Is there a more idiomatic way of doing this?

Answer 1

In Scala 2.8, you can use the deep method defined on Array, that returns an IndexedSeq cointaining all of the (possibly nested) elements of this array, and call mkString on that:

scala> val array = Array.fill(2,2)(0)
array: Array[Array[Int]] = Array(Array(0, 0), Array(0, 0))

scala> println(array.deep.mkString("\n"))
Array(0, 0)
Array(0, 0)

The IndexedSeq returned does have a stringprefix ‘Array’ by default, so I’m not sure whether this gives precisely what you wanted.