After reading the Java language book twice, I had a certain theoretical understanding, but I had no idea how to use the theories I had learned. The moment I listened to this lecture, it was a bit sensational. I thought that Java could be taught like this. There were things I couldn't learn from the book, and while organically learning different concepts, I was able to realize how I could use them in practice and why I should learn this theory. Also, by expressing them in pictures in an easy-to-understand way, I was able to properly establish the Java language concepts that I had only abstractly understood, as it showed me how the sources I had written were applied to memory. I felt like a Jeon Han-gil teacher in the Java world because of his witty speech. I enjoyed listening to it. I will continue to listen to the rest of the lectures. I paid for the first part of SP, so I am looking forward to it.