I'll give you a bit of advice I give to engineers I mentor. Go to a tech jobs site like dice.com, and put in a technology you're curious about. So, put in java

I'll give you a bit of advice I give to engineers I mentor. Go to a tech jobs site like dice.com, and put in a technology you're curious about. So, put in java for your zip code. See what jobs are available. Are they back end? desktop? Then you'll find out where java (and any other tech) is used, and how popular it is. For example, how many jobs are there for PHP compared to Java? I'm not saying you should adapt a technology based solely on the number of jobs...but we all gotta eat. And on the flip side if you see Java jobs decline over the years...time to learn the one that's increasing :)