Having experience with Java, I'd advise him to take two or three months to learn Android programming. Then, either earn enough money selling is own Android app

Having experience with Java, I'd advise him to take two or three months to learn Android programming. Then, either earn enough money selling is own Android applications on the Play Store, or he'll find employment as senior Android developer or project manager. If he has a little more time, he could also learn iOS where they's also a lot of traction and job offers.