What do you suggest i should do after completing this course to become an expert

Answer 1

Youtube/ udemy + practice in eclipse making basic console app and gui app whats what i been doing so far

Answer 2

practice , practice and practice ....
Start Coding a small project

Answer 3

Im currently reading (headfirst java), learning/practicing (Udemy) and studying (degree in software engineering and oracle cert). But the best thing to do is just code! Practice reading and writing code as much as possible.