I am in astrophysics (lots of telescope and satellite data).
Our main point is that Java provides a complete environment: no shared libraries, no compilation problems when moving to other machines.
The next is productivity. In java, I could focus on the problem. In c/c++ it takes only minutes, until I have to think about why my code doesn't compile. That can easily take me away for hours, sometimes longer.
The most significant downside of java is for me memory consumption. It needs a lot of care and experience to get that right.
Python on the other hand is nice. Although it does not integrate with c++ as nicely as jython integrates with java.
