Read the stickies, above the android section. Android is NOT officially supported.
There is an "interest group" trying to implement android on a PI, but they have not gotten far, the various demo's on youtube and such are just that technical demo's, in practice Android is not usable.
in short, forget about using Android. The RPF has no interest in supporting it, its a medium for consumers, not for learning to program. *
* and yeah, I know you can have an opposing opinion about it, but that isn't influencing the RPF.