Why Android and Java?
A part of successful learning is the commitment by the student, not just to do the work, but in their belief that they are doing the right thing in the right way. So many technology-based courses and books don't get that commitment from the reader, not subconsciously anyway.
The problem is the students' belief that they might be, partly at least, wasting their time with something that is or will soon become outdated or perhaps is not quite right for them. This can be true to a large extent with programming. So why should you spend your finite time learning Java, on Android?
Android is the fastest evolving and growing OS ever
At one time, Android updates emerged almost every two months. Even now, they emerge about once in six ...