Android - restore last viewed Activity

Question

I have 3 different Activities that user navigates between in no particular order. My goal it twofold:

1. When user switches to something else when app is resumed

Answer 1

Keep in mind that onSaveInstanceState() isn't workable for long-term state, i.e. the user powers the phone down and then turns it back on at an indeterminate point later. You will need to create your own long-term state mechanism if you wish for your state to survive power cycles.