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Polymorphism Example in Java and Python

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Published: Sunday, 04 May 2025 04:18

Written by Super User

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In Java, you achieve dynamic polymorphism by overriding a method in a subclass and then referring to subclass objects via a parent class reference. The actual method that gets executed is determined at runtime based on the object type.

// Base class
class Animal {
    public void sound() {
        System.out.println("Animal makes a generic sound");
    }
}

// Subclass Dog overriding the sound() method
class Dog extends Animal {
    @Override
    public void sound() {
        System.out.println("Dog barks");
    }
}

// Subclass Cat overriding the sound() method
class Cat extends Animal {
    @Override
    public void sound() {
        System.out.println("Cat meows");
    }
}

// Main class to test dynamic polymorphism
public class DynamicPolymorphismDemo {
    public static void main(String[] args) {
        // Parent class reference pointing to a Dog instance
        Animal animal = new Dog();
        animal.sound(); // Output: Dog barks

        // Parent class reference now pointing to a Cat instance
        animal = new Cat();
        animal.sound(); // Output: Cat meows
    }
}

Explanation:

1. Method Overriding: Both Dog and Cat override the sound() method in the Animal class.

2. Dynamic Binding at Runtime: The reference variable animal is declared as type Animal, but when assigned a Dog object and later a Cat object, the correct overridden method gets called based on the actual object's type.

3. Flexibility: This allows for extending to more classes later, each with its own version of the sound() method, making the code more flexible and scalable.

Dynamic Polymorphism in Python

Python uses a similar approach. Due to its dynamic nature, method overriding in subclasses automatically ensures that the correct method is called based on the instance at runtime.

class Animal:
    def sound(self):
        print("Animal makes a generic sound")

class Dog(Animal):
    def sound(self):
        print("Dog barks")

class Cat(Animal):
    def sound(self):
        print("Cat meows")

def main():
    # List of different Animal objects
    animals = [Dog(), Cat()]
    
    # The correct sound() method is called for each object
    for animal in animals:
        animal.sound()

if __name__ == '__main__':
    main()

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