Hello, I have already paid for the teacher's lectures because I trust them not only for JAVA but also for SPRING. For your reference, I am currently studying Java on my own, and after listening to the Java basics lecture once, I listened to this lecture and the codes that I had been busy copying were approached with object-oriented concepts, so I understood why I had copied them that way. And since I had heard that object-oriented is important, I was able to finish the lecture after listening to it for 3 days thanks to the teacher's lectures that explained it easily with pictures and principles. Of course, I need to review it again, but if I just follow the API utilization lecture and NAP and SPR well... I think I can make something by self-studying. ------------ If you want to learn about the principles of object-oriented easily and properly, I highly recommend this lecture!!!