Hirerachial level inheritance

 public class hirearchialinheritance {

    public static void main(String[] args) {

        Mammal dog = new Mammal();

        dog.color = "Black";

        Bird eagle = new Bird();

        eagle.eat();

        Fish shark = new Fish();

        shark.breath();

        System.out.println(dog.color);

    }

}

class Animal {

    String color;

    void eat() {

        System.out.println("Eats..");

    }

    void breath() {

        System.out.println("Breathes..");

    }

}

class Mammal extends Animal {

    void walks() {

        System.out.println("Walks..");

    }

}

class Bird extends Animal {

    void fly() {

        System.out.println("Flies..");

    }

}

class Fish extends Animal {

    void swims() {

        System.out.println("Swims..");

    }

}