Simple overloading function puzzle in Java

StaticParamsDemo.java

class Base {
  public void foo(Base x) {
    System.out.println("Base.Base");
  }
  public void foo(Derived x) {
    System.out.println("Base.Derived");
  }
  public void bar(Object x) {
    System.out.println("bar-Base:Object");
  }
}
class Derived extends Base {
  public void bar(Derived x) {
    System.out.println("bar-Derived:Derived");
  }
  public void foo(Base x) {
    System.out.println("Derived.Base");
  }
  public void foo(Derived x) {
    System.out.println("Derived.Derived");
  }
}
public class StaticParamsDemo {
  public static void whichFoo(Base arg1, Base arg2) {
    arg1.foo(arg2);
  }
  public static void main(String[] args) {
    Base b = new Base();
    Derived d = new Derived();
    Base d2 = new Derived();
    System.out.print("b.bar(b): ");
    b.bar(b);
    System.out.print("b.bar(d): ");
    b.bar(d);
    System.out.print("d.bar(b): ");
    d.bar(b);
    System.out.print("d.bar(d): ");
    d.bar(d);
    System.out.print("d.bar(d2): ");
    d.bar(d2);
    System.out.print("d2.bar(b): ");
    d2.bar(b);
    System.out.print("d2.bar(d): ");
    d2.bar(d);
    System.out.print("d2.bar(d2): ");
    d2.bar(d2);
    System.out.print("whichFoo(b, b): ");
    whichFoo(b, b);
    System.out.print("whichFoo(b, d): ");
    whichFoo(b, d);
    System.out.print("whichFoo(d, b): ");
    whichFoo(d, b);
    System.out.print("whichFoo(d, d): ");
    whichFoo(d, d);
  }
}