How to Move from Beginner Java to Advanced Object-Oriented Programming — A Step-by-Step Guide
This transition isn't a big leap if you follow the right order

Short answer
Step 1: Confirm you've mastered Level One
Before anything, make sure you've mastered Java basics from Level One, since it's the foundation for everything ahead.
Step 2: Understand the difference between class and object
Start by understanding this core concept before moving to any other advanced concept.
Step 3: Master inheritance step by step
Learn the overridden concept and the super keyword through gradual practical examples.
Step 4: Learn exception handling
Master using try, catch, finally to write stable code that handles unexpected errors.
Step 5: Apply all concepts to real exercises and projects
Don't stop at theoretical understanding — apply each concept yourself so it truly sticks.
To learn these steps in detail, the Java Level Two (OOP) course on Traivis takes you through exactly this order, in 3 hours 3 minutes of intensive practical application.
Who is the instructor?
The course is taught by Nibras Alissa, who holds a master's degree in Computer Information Systems from Yarmouk University in Jordan, and previously lectured at Taibah University in Saudi Arabia. His experience spans over 20 years in university teaching, with 100% professional-level proficiency in Java, Python, C++, and SQL.
After finishing Level Two, the natural next step is Data Structures and Algorithms in Java Level Three, and if you'd like to learn another language, Nibras Alissa also teaches C++ from Scratch on Traivis.
Takeaway
Object-oriented programming isn't complex if learned in a logical order with practical application.
Links
Enroll on Traivis: https://traivis.com/ar/courses/mastering-data-analysis-with-microsoft-power-bi
Instructor profile: https://traivis.com/ar/profile/nibras-alissa
Related course 1: https://traivis.com/ar/courses/trakyb-albyanat-oalkhoarzmyat-data-structure-and-algorithms
Related course 2: https://traivis.com/ar/courses/taalm-sy-bls-bls-mn-alsfr-c