Java URLEncode question?

Yes, the w3schools.com page does say that. I remember using "+" for <space> in URLs a long time ago. I think %20 became the more commonly used replacement, perhaps related to the introduction of URIs. The earlier RFC 2396 specified %20, as does the current authoritative document RFC3986.

http://tools.ietf.org/html/rfc3986#section-2.1

Or maybe because Javascript uses only %20 when encoding. Anyway, either should work. The problem probably doesn't involve Firefox at all. The problem almost certainly resides in the server. I'm guessing the server-side code is decoding the HTTP request, and when it parses the requested resource from the GET request line, it isn't properly replacing the "+" with a blank when it searches for the "a file.mp3" resource.

I think you're a little confused. The encoded version of a space is %20, not a plus sign. "a file.mp3" and "a+file.mp3" are two different files.

Edit:

You're correct that URLs shouldn't contain spaces, but URL encoding replaces a space with %20, not a plus sign. I'm not sure where you're getting the plus sign thing from; the page you linked to does not mention it.

That's because it's uhmm.. Hex I think, and %20 is just instead of a space, while a + has the value of %21 I think..

So if you type in server.com/my index/index.html the browser (Modern once at least) automatically converts the space into %20, so it becomes readable, same with the plus, the browser converts it into %21 (Or whatever the code is) so that it's readable..

Hope this helped!