en_US or en-US, which one should you use? [duplicate]

Answer 1

I don't think en-US is a standard at all for Java. (If you see it somewhere could you add a link).

So just use en_US.

Answer 2

In Java 7, there is a new method Locale.forLanguageTag(String), which assumes the hyphen as a separator. I'd consider that as normative.

Check the documentation of Locale for more information.

Answer 3

Wait, wait, wait. Guys, I'm pretty sure "-" is the standard. If you see "_" somewhere it's probably something some people came up with to make it a valid identifier.

Personally I'd go with "-", just to be correct.

http://en.wikipedia.org/wiki/IETF_language_tag

http://tools.ietf.org/html/rfc5646

Answer 4

en_US. This is a very useful read.

Answer 5

If you're working with Java, you might as well use the Java locale format (en_US).

The BCP 47 documents actually do specify the en-US format, and it's just as common if not more common than Java-style locale names. But in practice you'll see the form with the underbar quite a bit. For example, both Java and most POSIX-type platforms use the underbar for their language/region separator.

So you can't go far wrong with either choice. But given that you're writing in Java and probably targeting a Unix platform, en_US is probably the way to go.