geonik

  enum Type {
    ANIMAL(null),
    MAMMAL(ANIMAL),
    DOG(MAMMAL) {
      public void makeNoise() {
        System.out.println("Woof");
      }
    },
    CAT(MAMMAL) {
      public void makeNoise() {
        System.out.println("Meow");
      }
    };
    private Type parent;
    Type(Type parent) {
      this.parent = parent;
    }
    public boolean isA(Type type) {
      if(this == type) return true;
      if(parent != null) return parent.isA(type);
      return false;
    }
    public void makeNoise() { }
  }
  assert Type.DOG.isA(Type.MAMMAL) == true;
  assert Type.CAT.isA(Type.DOG) == false;
  Type.CAT.makeNoise(); // "Meow"