Yes, by all means learn Java. It's not as hip as Go or JavaScript, nor as versatile as Lisp. Learn it because it's still a valuable utility language for writing networked services (especially large ones) and it has HUGE library support. Learn it for the hell of it. And don't be swayed by its reputation; Java in 2018 is asymptotically approaching Kotlin (which you may also want to learn, as long as you're on the JVM).