Why are singleton objects more object-oriented?

Question

In Programming in Scala: A Comprehensive Step-by-Step Guide, the author said:

One way in which Scala is more object-oriented than Java is that cla

Answer 1

It's more object oriented in the sense that given a Scala class, every method call is a method call on that object. In Java, the static methods don't interact with the object state.

In fact, given an object a of a class A with the static method m(), it's considered bad practice to call a.m(). Instead it's recommended to call A.m() (I believe Eclipse will give you a warning). Java static methods can't be overridden, they can just be hidden by another method:

class A {
    public static void m() {
        System.out.println("m from A");
    }
}
public class B extends A {
    public static void m() {
        System.out.println("m from B");
    }
    public static void main(String[] args) {
        A a = new B();
        a.m();
    }
}

What will a.m() print?

In Scala, you would stick the static methods in companion objects A and B and the intent would be clearer as you would refer explicitly to the companion A or B.

Adding the same example in Scala:

class A
object A { 
  def m() = println("m from A") 
}
class B extends A
object B { 
  def m() = println("m from B")
  def main(args: Array[String]) {
    val a = new B
    A.m() // cannot call a.m()
  }
}