// Polymorphism.java

public class Polymorphism {

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

   public static void doFooInterface(FooInterface f) {
      f.foo();
   }

   public static void doFoo(Foo f) {
      f.foo();
   }

   public static void demoPolymorphism() {
      doFoo(new Foo());
      doFoo(new Bar());
      doFooInterface(new Fooey());
      doFooInterface(new Barey());
   }
}

class Foo {
   public void foo() {
       System.out.println("Foo!!!");
   }
}

class Bar extends Foo {
   public void foo() {
      System.out.println("Bar!!!!");
   }
}

interface FooInterface {
   public void foo();
}

class Fooey implements FooInterface {
   public void foo() {
       System.out.println("Foo Interface!!!!");
   }
}

class Barey implements FooInterface {
   public void foo() {
      System.out.println("Bar Interface!!!!!");
   }
}