You may be wondering why you should become a mobile developer? I can cite two strong reasons, one of which never existed before. The familiar one is to be part of an IT organization for their mobile programming efforts. The IT opportunities are on the raise but not fully realzied yet unlike what happened with the Web programming paradigm when it came into being. I expect this need, however, to be a gradually increasing demand.
On the other hand, the immediate and exiciting opportunity is for you to become an independent app publisher. The availability of a sales channel for the apps that you write is a unique one in the software industry. Not every one of us is going to be a raising star in an IT organization. The independent developer path gives an avenue for you to grow at your own pace and in the direction that satisfies you. Luck and Patience might even make you rich. At least you can add value to the society in meeting your needs.
So should you decide to venture into the android mobile programming space you want to be prepared with the right hardware that makes this experience bearable. If you are buying a windows laptop see if you can get one with at least 8G of memory, solid state hard drive, and a reasonably fast processor. Expect to spend about a $1000 to a $1500. If you are buying a Mac laptop, similar configuration may cost you about $2500. A good fast configuration is important for android development.
If you are a seasoned Java programmer, given this investment, and a few good books in hand you can expect to be a competent mobile android app devloper in about 6 months.
Should you decide to take this on you may want to follow a well laid out road map for accomplishing the goal of creating meaningul, relentelessly useful apps, not for, but using the Android platform.