I'm not sure why people don't use cross-platform GUI toolkits more often. I tend to write my GUI in Java, and transfer control over to C++ for the actual program logic. If you know about the MVC architectural pattern, you can use Java to implement the view and controller, and C++ to implement the view. If the program is simple and performance isn't critical, then I often code everything directly in Java. I've listed a few pros of cons of using Java for coding UI instead to other languages below.
Pros
- Java already has a large library full of useful utilities, and is a good starting point from which one may learn other languages. There's many well-tested Swing components that are ready to use, and tutorials online that give you good starting points for many common use cases.
- Check out the JogAmp website, and try out their demos. I prefer using C/C++ to do the rendering and Java only for the user-interface, but if performance is not critical, the JogAmp APIs a lot of flexibility in terms of controlling which subset of OpenGL you would like to use.
- Java has extensive support for databases and servlets - check out the JDBC API.
- Java is open-source, and does not restrict you to using a particular IDE (or operating system!).
- Java comes with a builtin documentation generator called Javadoc, and it works really well. In fact, documentation for the JDK is generated using it.
Cons
- Java is an interpreted language, so performance will typically be worse than that of other compiled languages.
- Java forces you to frame your entire program logic using objected-oriented principles, even when they aren't a good fit for your particular use case (e.g. simple, one-off experiments). Sometimes your code can end up being much more verbose than it needs to be in order to accomplish a particular task.
Edit: There are plenty of resources for beginners, such as this one.
