Different Views for different users in android -

i beginner in android , planning build app have different views based user type. when user signs up, based on id, see view different view user b sees (when signs using id). please guide how achieve this. users authenticated database based on category. each category type want have different view , subsequent screens. pointers relevant links, tutorials helpful.

my second question: user completes activity , presses button, user b should notification (say color change) of same. mean status updates different users of activity completion should updated , seen @ runtime.

my sincere apologies if sees questions basic level 1 have searched web , didn't find relevant links(may not searching right way).

any sort of guidance highly appreciable. thanks.

get category of user database , set activity upon category or make views visible or gone based on category. can't understand second question though.