Android up navigation for an Activity with multiple parents

Question

I have a problem for implementing up navigation on an app with this navigation tree:

Answer 1

That's a tricky question and in my opinion really shows the difficulties in coping with the UX decisions of Android for the "up button". Therefore, there's not a clear-cut answer to your problem.

I have two possible solutions for you.

1. Mimicking the back button behavior.

You could consider adding an extra to the intent for launching Detail from one of its various parents. This extra would inform those activities which activity they would need to launch when android.R.id.home is pressed.

This would effectively mean that your app "goes back" to its common ancestor, instead of simply relaunching Home.

Another way of implementing this may be simply executing onBackPressed() instead of launching Home with Intent.FLAG_ACTIVITY_CLEAR_TOP, but bear in mind that the associated animation would be different than a normal "up" action.

2. Skip intermediate activites and go home.

Some apps treat the "up button" as a "home button". You might want to consider having it simply always relaunch Home with Intent.FLAG_ACTIVITY_CLEAR_TOP.