Great to know you have JAVA skill!
It is enough to find a job with your high skilled JAVA.
Many companies are using JAVA.
.NET is good for MSFT system. Therefore, besides high tech companies, .net is also widely used in small and middle companies, and used in gov, school, and medical places.
With your JAVA in hand, learn .NET will not hurt you.
You may also use .net under Linux which named mono.
Anyway, JAVA is a good thing, don't forget it. Pick up .NET will make your skill wider to find a job.
Thanks!