Like the title says, my first job out of college was/is a java development role. I do database level (stored procedures) and front-end stuff (html, css, js, etc) as well so I am technically full stack.
I have seen a few job openings that advertise transitioning into python or ruby without needing the experience. Is it worth time and effort to program in a different language for awhile?
What is best for a career path as a software engineer?
Do you dislike Java as a language (or feel it is technically inadequate in some way)?
Do you feel that it would be good for your career to know more languages?
If you've been out of college, and you're able to find work with what you know, I'd say your career priority is to get better at what you know. Become "master of one" before worrying about "jack of all trades". (I'm not saying "don't learn another language", but it's lower priority.)
But if you feel that Java is inadequate for the kinds of programs you want to write, or if you feel like you are on a career dead end without learning more, then make learning a new language your priority.