Java and PHP are very different.
It depends on your skill level, but I find Java to not be that hard compared to other programming languages like LISP or Scheme.
There are lots of edX and other MOOC courses you would want to enroll in, which can give you both solid understanding and a certificate at the same time.
I found out that credentials from edX and Datacamp are seemingly pretty appealing to recruiters.
Good luck, and use a lot of
stackoverflow (site) for questions and answers!
Edited by stingraze 2017-08-09 11:20 PM