How would you import an external library into processing?

I have this game in which I want to use an AI engine for the opponent, but it requires I use an external file as making an AI for this game is VERY complicated. However, I found a great java library that has everything I need, but I cannot import it into processing. It doesn’t come with a jar file, so how do I import it?

Actually, instead of using the library, I found that I can make a process using processbuilder, and then I can send data to the process using outputstream