You are in danger of falling in tutorial hell: endless video and and article tutorial on Java. No.
Mosh will explain the why and how of every concept he teaches you. And he goes in-depth on every major concept. Watch the videos, and code along. Then code new things from what you learn from the video, with what you learned in the videos. Don’t get ahead. The course starts “light”, and then it thrusts you into the deep Java mechanics because it assumes you learned everything else Mosh taught you first. Don’t get overwhelmed learning “one more thing” outside of this course, until you finish the full course.
I think, trying to understand ‘why’ and ‘how’, and practicing in the go helps you better consume the material. How ever, the most important thing is to have a clear and specific goal regarding how you will use the knowledge at the end of the day. will you be a backend java developer (of course with framework)? or Will you be java course instructor? or What?
If you want to be a java backend developer, you don’t have to stay long in your first go trying to master by watching and practicing the videos only, this is only the first phase, you have to invest much time building projects, and thats how you will master it. And, whenever necessary, you can come back to the videos to refer concepts. This way lets you better understand the concepts in the video. Also, Don’t try to be flawless and perfect, just make sure to try to build on your own then see the instructor’s solution to get feedback for your improvement.