OOP Fundamentals • PolymorphismEasy⏱️ ~2 min
What is Polymorphism?
Definition
Polymorphism is the ability of objects to take multiple forms, allowing a single interface to represent different underlying implementations. It enables you to write code that works with a parent type but executes behavior specific to the actual child type at runtime.
What Problem Does It Solve?
Without polymorphism, you would need separate methods for each type of object, leading to code duplication and tight coupling. Consider a payment processing system:
Without Polymorphism:
processCreditCard(creditCard)
processDebitCard(debitCard)
processPayPal(paypal)
processUPI(upi)
processDebitCard(debitCard)
processPayPal(paypal)
processUPI(upi)
Every new payment method requires a new method, violating the Open/Closed Principle (OCP). Polymorphism solves this by allowing a single processPayment(paymentMethod) method to handle all types.
Core Benefits
First, extensibility: Add new types without modifying existing code. Second, flexibility: Client code depends on abstractions, not concrete implementations. Third, maintainability: Changes to one implementation do not affect others.
Interview Tip: Always distinguish between compile-time (method overloading) and runtime polymorphism (method overriding). LLD interviews focus on runtime polymorphism through inheritance and interfaces.
💡 Key Takeaways
✓Polymorphism allows one interface to represent multiple implementations
✓Solves the problem of code duplication and tight coupling when handling different types
✓Enables Open/Closed Principle: open for extension, closed for modification
✓Runtime polymorphism (overriding) is more relevant to LLD than compile-time (overloading)
📌 Examples
1Payment processing: single processPayment() method handles CreditCard, DebitCard, UPI
2Notification system: sendNotification() works with Email, SMS, Push implementations