Using GTK+ from both Java and native C++ on Windows

I have to write a program for my final project in my Java class. My program must be written in Java and it must be cross platform compatible (meaning it will run on two different operating systems).

At the same time, I am writing a completely different program for my final project in my C++ class and I would like to write a GUI for it. I have much more flexibility in writing it than I do with my Java program, which must be strictly Java.

Rather than learning two completely different APIs, I would like to use GTK+ in place of the AWT and Swing libraries for my Java program and in place of Winforms for my C++ application. I have spoken to both of my professors and this is acceptable.

My question is, how do I do it? If someone could point me towards or provide me with directions for getting simple Hello World applications running in both languages on Windows using GTK+ (preferably in Visual Studio for C++ and Eclipse for Java), I should be able to work from there.