It may not be worth getting good at it, unless it's purely a way to get a job at a big company.
Brightest futures seem to be Python (for data science and AI), Rust, Elm, Kotlin, Go, maybe F#, and probably Swift.
Regarding Java, i think its a good starting point if you want to hack your first web project together. You sort of see how everything works together. Before that I always recommend looking at C just to know what you are missing out on. If there is some calculation happening you can always call some C/C++ code to see if you get some speed ups by optimizing for the cache (just an interesting experiment if youve never done it before.