I just checked out your book at Amazon and I would like to know if you have a publisher in India?
Not presently, sorry.
or is there a possibility to buy a pdf version of the book online?
Absolutely! The
Warescription gives you access to CommonsWare library (one Android book finished, two Android books in progress), including all new titles and updates, for a year. You get the books in PDF or Kindle formats...though PDF is recommended.
I'm seriously considering myself to get some hands on in Mobile development using Java and I feel Android might be the right platform.
For experienced Java developers, it is certainly the easiest to get started in.