5 months into Java

Hello! I've been studying Java for a semester now in school (Learned the basics for 2 months and object oriented programming for 2 months). I have a 3 week break and was looking for a 1-2 week intensive bootcamp to get better during these vacations. However all of the courses are super basic and teach stuff like how to print messages and how to create arrays. I'm looking for a way (doesn't have to be a course, but if it is, should be a bit more advanced) to get better during these two weeks. Thanks for your tips/help!