OOP Fundamentals • Abstraction & InterfacesEasy⏱️ ~2 min
What is Abstraction in OOP?
Definition
Abstraction is the process of hiding implementation details while exposing only essential behaviors through a simplified interface. It focuses on what an object does, not how it does it.
Abstraction solves two critical problems in object-oriented design:
First, it reduces complexity by allowing clients to interact with objects through a simple contract without understanding internal mechanics. A driver operates a Car using accelerate() and brake() without knowing engine combustion or hydraulic systems.
Second, it enables loose coupling by defining contracts (interfaces or abstract classes) that multiple implementations can satisfy. This allows interchangeable components and easier testing.
«interface»
PaymentProcessor
+ processPayment(amount): Result
▲
CreditCardProcessor
+ processPayment()
PayPalProcessor
+ processPayment()
Interview Tip: Always distinguish abstraction (hiding complexity) from encapsulation (hiding data). Abstraction is about design-level simplification, while encapsulation is about data protection.
💡 Key Takeaways
✓Abstraction hides implementation details and exposes essential behaviors through a contract
✓Interfaces and abstract classes are the primary mechanisms for achieving abstraction
✓Reduces coupling by allowing clients to depend on abstractions rather than concrete implementations
✓Focuses on "what" behavior is provided, not "how" it is implemented
📌 Examples
1PaymentProcessor interface hides whether payment uses credit card, PayPal, or cryptocurrency
2Database interface abstracts whether storage is SQL, NoSQL, or in-memory