Android developement has a lot of walk-throughs that are mostly helpful. You'll have to know XML on top of java to use the android studio (or atleast you did in spring when I used it).
If you want to dual-create an app for both andriod and iOS there is a framework that allows you to do that in java without buying the iOS developement kit. I don't have first-hand experience with this though, but TA'd some students working on it. I think they used this:
http://www.appcelerator.com/titanium/