
Here's a book to get you started:
https://www.amazon.com/Java-Beginners-Guide-Herbert-Schildt-...
Now I've found Python, which has a lot of the characteristics of Mathematica, and is very fun. But I have to fix my Java printing issues before I can play with it. (If I can figure out how to deploy it as a GUI desktop app I could better justify spending more time with it).