multi-level inheritance

 public class singleinheritance {

    public static void main(String[] args) {

        Dog boomer = new Dog();

        boomer.eat();

        boomer.legs = 4;

        System.out.println(boomer.legs);

    }

}

// BASE CLASS

class Animal {

    String color;

    void breath() {

        System.out.println("Breathes");

    }

    void eat() {

        System.out.println("Eats");

    }

}

// DERIVED CLASS

class Mammal extends Animal {

    int legs;

}

class Dog extends Mammal {

    String breed;

}