array.scala

package array

class Test {
  def callSize(arr: Array[Int]): Int = arr.size
  def callLength(arr: Array[Int]): Int = arr.length
}

javap-output

public class array.Test {
  public int callSize(int[]);
    Code:
       0: getstatic     #16                 // Field scala/Predef$.MODULE$:Lscala/Predef$;
       3: aload_1
       4: invokevirtual #20                 // Method scala/Predef$.intArrayOps:([I)Lscala/collection/mutable/ArrayOps;
       7: invokeinterface #26,  1           // InterfaceMethod scala/collection/mutable/ArrayOps.size:()I
      12: ireturn

  public int callLength(int[]);
    Code:
       0: aload_1
       1: arraylength
       2: ireturn

  public array.Test();
    Code:
       0: aload_0
       1: invokespecial #35                 // Method java/lang/Object."<init>":()V
       4: return
}