Now on the labor market demand for Java. Not only now but in the past and in the future this platform will be popular and will continue to be in demand.
The question is, what do you want to work for a large firm, where Java is used for a specific project and continue to work with her OR to get into a small "office" where you can be "rank", to develop medium and small projects.
In the second case is clearly the Python, not Django, and Pyramid or Pylons. My personal opinion — the use of Java in the medium and small(small) projects — evil, and Django is not the best web framework.
Halvorsen: this is all my personal opinion, on a personal and not only experience, and persuade me not.