Java inheritance

gistfile1.java

interface Animal {
    void eat()
}

class Mammal implements Animal {
    void eat() {
        System.out.println("mammal eating");
    }
}

class Dog extends Mammal {
    void eat() {
        System.out.println("dog eating");
    }
}

class App {
    public static void main(String[] args) {
        Mammal mammal = new Dog();
        mammal.eat();
    }
}