CODEWITHSUNDEEP
arraysscalatypes
prosseek
prosseek

Reputation: 191159

Type mismatch with Array of Array in Scala

I'm trying to build an array of an array to give it as a argument to a method. The value of inner arrays are any kind of data (AnyVal) such as Int or Double.

The method's signature is as follows:

def plot[T <: AnyVal](config:Map[String, String], data:Array[Array[T]]): Unit = {

This is the code:

val array1 = (1 to 10).toArray
val array2 = ArrayBuffer[Int]()
array1.foreach { i =>
  array2 += (getSize(summary, i))
}
val array3 = new Array[Int](summary.getSize())

val arrays = ArrayBuffer[Array[AnyVal]](array1, array2.toArray, array3) # <-- ERROR1
Gnuplotter.plot(smap, arrays.toArray) # <-- ERROR2

However, I have two errors:

enter image description here enter image description here

What might be wrong?

Upvotes: 1

Views: 1483

Answers (1)

Gabriele Petronella
Gabriele Petronella

Reputation: 108169

Array, being a mutable data structure, is not covariant (here's why)

So Array[Int] is not a subtype of Array[AnyVal], hence you cannot pass it where an Array[AnyVal] is expected.

Would a List do for you purposes?

In case performance matters and you really need to use Array, you can simply cast everything to an Array[Any] and be done with it.

Alternatively, if you just need an Array[Any] as the final type to pass to the plot function, you can do everything with List, and convert it with toArray[Any] at the very end.

Upvotes: 6

Related Questions