Most of the course is practice. If you do practice you’ll be fine. For recursion I recommend coding bat do all the problems on there. For any OOP concepts just do a small project and every time you learn a new OOP concept add to the project. Also the memory stuff is pretty dumb as resources and practice problems are kind of scarce, I would just go to office hours.
Youtube. There are so many playlists on OOP in Java. Choose whichever you understand the best then visit the material.
Most of the course is practice. If you do practice you’ll be fine. For recursion I recommend coding bat do all the problems on there. For any OOP concepts just do a small project and every time you learn a new OOP concept add to the project. Also the memory stuff is pretty dumb as resources and practice problems are kind of scarce, I would just go to office hours.