Object-Oriented Programming
Classes bundle data and behavior into objects.
About this topic
Object-oriented programming (OOP) organises code around objects that combine data (attributes) and behaviour (methods). A class is a blueprint, and objects are individual instances built from it. For example, a Dog class may have name and age attributes and a bark method, and each dog created is its own object.
Four main ideas support OOP. Encapsulation hides internal details and exposes a simple interface. Abstraction focuses on what an object does rather than how. Inheritance lets a new class reuse and extend an existing one, so a Puppy class can inherit from Dog. Polymorphism lets different classes respond to the same method in their own way, so a Cat and a Dog both have speak, but they sound different.
OOP helps manage large programs, such as games with players, enemies and items, or banking systems with accounts. A common misconception is that more classes always means better design; overusing inheritance can make code tangled. Another is confusing the class with the object: the class is the cookie cutter and the objects are the cookies. Model real things carefully and keep each class focused.
Key ideas
- Class vs object
- Inheritance and polymorphism
- Encapsulation
Quick check
Use cases: where Object-Oriented Programming helps
- Homework: review the key idea behind Object-Oriented Programming before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Object-Oriented Programming without notes.
- Visual learning: play with the interactive lab to see how Object-Oriented Programming changes when you adjust its inputs.
- Teaching a friend: explain Object-Oriented Programming in your own words, then compare your version with the key ideas.
Computing ideas run phones, search engines, games and the wider internet.
Frequently asked questions
What is Object-Oriented Programming?
Classes bundle data and behavior into objects.
What will I learn in Object-Oriented Programming?
Class vs object. Inheritance and polymorphism. Encapsulation.
Is Object-Oriented Programming part of Computer Science?
Yes. It is one of 80 Computer Science topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Object-Oriented Programming lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Object-Oriented Programming?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.