Long lasting future Technology option

Question

I am currently an Android developer in ahmedabad. My mind stuck with the technology future of android. My brother who has experience in Java for 6 years adviced me to switch over to Java technology which is good as a career instead of Android which is currently growing technology. I cant understand what to do next. Its not like that I don't like Android, but I like to hold hand of a technology which grow me high in my career.