Free online course Java Object Oriented Programming

About the free online course

Object-oriented programming is the foundation behind most professional Java applications, and learning it well is one of the quickest ways to write cleaner, safer, and easier-to-maintain code. In this free online course, you will move beyond syntax and start thinking in objects: how to model real-world concepts as classes, how to protect data, and how to design programs that scale as they grow.

You will begin by understanding the core idea of OOP in Java and why it matters in modern development. From there, you will practice creating well-structured classes and controlling access to data through encapsulation. Getters and setters help you enforce rules, validate input, and reduce bugs by keeping fields protected while still allowing intentional access. This course emphasizes the kind of habits that lead to reliable codebases and smoother teamwork.

As you progress, you will explore how Java supports flexibility through method overloading and method overriding. You will learn how to design methods that are intuitive to call in different contexts, and how overriding enables customized behavior in child classes without rewriting everything from scratch. Constructors are covered in a practical way so you understand how objects are initialized, how default and custom constructors differ, and how proper initialization improves correctness from the first line of execution.

The course also introduces generic lists so you can work with collections in a type-safe, reusable way—essential for real applications that handle groups of objects. You will then dive into static data members and static methods, clarifying when data or behavior belongs to a class as a whole versus to each instance. These topics are often misunderstood by beginners, so the lessons focus on building clear intuition you can apply immediately.

Finally, you will connect everything through inheritance and polymorphism, two concepts that power extensible systems and reusable designs. By the end, you will be able to read and write Java code that reflects common industry patterns, communicate more confidently about OOP in interviews, and build projects that are easier to expand without breaking existing features.