I happen to work for a company in the financial sector.

Our developers use Java (mostly).

Our research department uses whatever they are most comfortable with for research, but the result of their research is coded up in C++. If we had to do it over, we'd probably do everything in Java. Misc. notes:

Personally, I am WAY more productive in Java.

I supplement Java with Clojure.

I find the performance penalty for using Java is pretty-much negligible. It's always how you do it that matters more than what language you do it in. Don't use Java Generics for number crunching though... use a dedicated primitives collection library like Colt.

Java and C++ are quite similar in some respects. I would say though, that it's easier to go from C++ to Java, than from Java to C++.

Best C++ books:

Accelerated C++ by Andrew Koenig and Barbara E. Moo

Effective C++ by Scott Meyers (make sure you get the 3rd edition)

Best Java books:

Effective Java by Joshua Bloch

Java Concurrency in Practice by Brian Goetz, Tim Peierls, Joshua Bloch, and Joseph Bowbeer

If you have to use C++, start using the Boost C++ libraries early on. You can learn a great deal just by using the Boost libraries, and reading their documentation.