In Scala, arrays are not covariant.

Convariant.java

package freestrings.playground

public class ConvariantInjava {

  class A {
	}

	class B extends A {
	}

	{
		B[] b = new B[] { new B() };
		A[] a = b;
		a[0] = new A(); // ==> runtime error ( java.lang.ArrayStoreException )
	};

	public static void main(String[] args) {
		new ConvariantInjava();
	}
}

Covariant.scala

package freestrings.playground

object CovariantInScala {

  class A {}
  class B extends A {}

  val b: Array[B] = Array(new B())
  val a: Array[A] = b // ==> compile error
  
}