Polymorphism

Polymorphism = "many forms"

In Java, it allows the same method name to perform different behaviors based on:

• The number/type of arguments (Compile-time)

• The actual object used at runtime (Runtime)

💡 Real-Life Analogy

A person acts differently in different roles: As a student, they attend class. As a friend, they hang out

→ One person, many behaviors — that's polymorphism.

🧠 Types of Polymorphism

🛠️ Compile-Time Polymorphism (Method Overloading)

🔸 Same method name, different parameters

class Calculator {
    int multiply(int a, int b) {
        return a * b;
    }

    int multiply(int a, int b, int c) {
        return a * b * c;
    }
}

public class Main {
    public static void main(String[] args) {
        Calculator c = new Calculator();
        System.out.println(c.multiply(2, 3));       // 6
        System.out.println(c.multiply(2, 3, 4));    // 24
    }
}

6
24

✅ Why use it?

To handle multiple versions of a method with different input types or counts.

🔁 Runtime Polymorphism (Method Overriding)

🔸 Same method name, same parameters, different behavior (due to inheritance)

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

class Cow extends Animal {
    void makeSound() {
        System.out.println("Cow says Moo");
    }
}

public class Main {
    public static void main(String[] args) {
        Animal a = new Cow();  // parent reference, child object
        a.makeSound();         // Cow’s version is called
    }
}

Cow says Moo

✅ Why use it?

To achieve dynamic behavior — the actual object decides which version of the method runs at runtime.

🔍 Key Differences