Where can I find other people's Java projects to read the code and practice?

Question

Java

Hello!
Now I'm learning Java, and so far I can't find any practical application for my knowledge.
Where can you find other people's projects that were put into practice in order to read them and learn some things for yourself.
I am interested in projects on Java SE itself (Except for Swing, I don’t know it)
PS Yes, yes, I know that you can find projects on github, but libraries and some APIs are mainly published there
Thank you)

Answer 1

chapter 6 paragraph 5 and 6