Object Oriented Programming in Java by Kunal Kushwaha

About this course

Build Java programs that are easier to maintain, extend, and scale by mastering object oriented programming from the ground up. This free online course guides you from the moment an object is created in memory to the design decisions that make real applications resilient over time. You will learn to think in terms of classes, objects, and responsibilities so your code reads clearly, avoids duplication, and stays flexible as requirements change.

You will practice core OOP principles—encapsulation, inheritance, polymorphism, and abstraction—and understand when each one improves design rather than complicates it. Along the way, you will work with packages, access control, and the Object class, helping you write code that behaves predictably across modules and teams. You will also gain confidence with static members, singleton-style patterns, and the built-in methods Java developers use daily.

As you progress, you will connect OOP to modern Java development by exploring abstract classes, interfaces, and annotations, including how Java supports multiple inheritance through interfaces. You will deepen your skills with generics to create type-safe components, and see how custom data structures can be designed with OOP thinking. The course also introduces practical features used in professional codebases, such as lambda expressions, exception handling, object cloning, and natural ordering for sorting objects.

Finally, you will become comfortable navigating the Collections Framework, understanding common list behaviors, legacy classes like Vector, and how enums fit into clean design. By the end, you will have a strong foundation to read and write idiomatic Java, contribute to backend projects, and approach interviews and assignments with a clear mental model of how OOP works in Java.