Question:

Consider the following Java code snippet:

class Animal {
    void sound() {
        System.out.println("Animal makes sound");
    }
}

class Cat extends Animal {
    void sound() {
        System.out.println("Meow");
    }
}

class Dog extends Animal {
    void sound() {
        System.out.println("Woof");
    }
}

public class Main {
    public static void main(String[] args) {
        Animal animal1 = new Cat();
        Animal animal2 = new Dog();

        animal1.sound();
        animal2.sound();
    }
}

Explain the concept of inheritance and polymorphism in the context of the given code snippet. Describe the output that would be produced when the code is executed. Provide a step-by-step explanation.

Answer:

Inheritance is a fundamental concept in Object-Oriented Programming (OOP) where a class can inherit the properties and behaviors (methods) of another class. The class that inherits is called the child or subclass, and the class being inherited from is called the parent or superclass.

Polymorphism is a concept that allows objects of different classes to be treated as objects of a common superclass. This means that a variable of the superclass type can refer to objects of its subclasses. When a method is called on a variable of the superclass type, the method defined in the subclass will be executed if it overrides the superclass method.

In the given code snippet, we have three classes: Animal, Cat, and Dog. The Cat and Dog classes inherit from the Animal class.

In the main method, two objects are created: animal1 of type Animal referring to a Cat object, and animal2 of type Animal referring to a Dog object.

When the sound method is called on animal1, since animal1 is referring to a Cat object, the sound method in the Cat class overrides the sound method in the Animal class. Therefore, the output would be:

Meow

Similarly, when the sound method is called on animal2, since animal2 is referring to a Dog object, the sound method in the Dog class overrides the sound method in the Animal class. Therefore, the output would be:

Woof

In summary, the output of the given code snippet would be:

Meow
Woof

This demonstrates the concept of polymorphism, where objects of different classes (Cat and Dog) are treated as objects of a common superclass (Animal) and the appropriate method implementation is executed based on the actual object type being referred to.