val arr1 = Array( 1, 2, 3 )
val arr2 = Array( 4, 5, 6 )
val arr3 = Array( 7, 8, 9 )

arr1 ++ arr2 ++ arr3
//or:
Array concat ( arr1, arr2, arr3 )
// res0: Array[Int] = Array(1, 2, 3, 4, 5, 6, 7, 8, 9)