During interview:

Them - "what was the last thing you've learned?"
Me - "Java, actually. Learning it for a personal project."
Them - "Why Java? What purpose does it serve?"
Me - "ಠ_ಠ"

I bet they wanted you to be able to reason why you specifically needed Java for your project.

@Trey50Daniel aye and portability was the answer. Linux, Mac and Windows

I'm always paranoid that languages or frameworks I'm using will be obsolete and submarine my career; so, when I see increasing talk or job postings with languages I don't know, I'll build something in it just to hedge my bets.

@dkomito one of my favorite things to do is to rebuild a web app in a new language. That way it's easy to do side by side comparisons since it's the same app, just diff languages.

@emes001 basically your own Rosetta stone.