I am trying to listen to a lecture that is over 20 hours long, so I am also exhausted. However, the lecture notes with many pictures were very helpful. I only knew how to use Runnable when it comes to threads, but I was a little surprised to see that there were more things to learn than I thought. I am also looking forward to the next advanced lecture. Lambda, stream... When I look at the source code for this kind of code, it is still very difficult.