get back stack activity

Question

I have 2 Activities ActivityA & ActivityB, if you open ActivityA and select anything from it, it will open ActivityB, and when you finish ActivityB it will go back to ActivityA, how can i open ActivityB lets say from a notification, and when user finishs it, if there is nothing in back stack I opens ActivityA, am asking about the best solution for this, I already have ideas about that, but still not sure if this is the best solution for it.

in ActivityB

Intent intent=new Intent(getApplicationContext(), ActivityA.class);
intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
startActivity(intent);

finish();

or I can send a flag from ActivityA to ActivityB when I start B from A, if this flag exists, I just finish, if not, I start ActivityA.

Answer 1

use startActivities() and pass both activities. Android will handle the back stack for you