To get your day rate up, though, you're going to have to build up your own network, so that you're not competing against everyone else on the freelance sites. Check out Brennan Dunn's books/blog/email list. [1][2]
If you're good and get the right connections, you should be able to get up towards that $100/hr mark. To get beyond that, you really need to be able to point to a bank account and say, "because of me, there's more money there." See patio11 [3]. At that point, language is far less relevant - and in fact, I'd hazard a guess that Java is a particularly difficult language to do that with (because it tends to be more backend rather than front-end, but that's an unsubstantiated gut feel.)
[1] http://doubleyourfreelancingrate.com/ [2] http://brennandunn.com/ [3] https://training.kalzumeus.com/newsletters/archive/consultin...
For Java (which I have 15 years fulltime experience with including backend and frontend frameworks)/C# and iOS/Android the freelance sites are infested with $5/hour workers from the east who will not finish anything, write crazy unreadable code and most of them also do 3+ jobs at the same time, making sure you get the lowest grade. Exceptions are there, but I have done outsourcing for many years and the 'start you off with a senior to get you in and then replace with a junior who cannot do anything' is more normal and the reason we stopped doing it all together.
I am trying to use danielstudds advice here as well, but find it hard. All promises of 'premium freelance' sites never worked (while my gut says it still should by the way; site with rigorous intake with a minimum level of acceptance (if you have no talent at all then go fix that elsewhere first), having a panel of experts in different development areas who interview and assess you every 3 months and set your level(s) and price goals).
And i'm a social animal but I unfortunately hang out most with coders who 'already made it' (and don't care about work and have no connections anymore of that kind) or academic researchers (I would go for a position like that the rest of my life, but my credentials aren't good enough to say that I want to sit on a mountain working on formal methods and programming languages) or artists.
Good luck to fellow searchers.
Please contact me at info@brightinventions.pl. We might have sth for you.
Good programming does not have a lot to do with the particular programming language involved, IMHO.