Whether or not to use multiple instances of an Activity on Android?

Issue

If I have an app that refills a ListView with different data in response to a user selecting an item. Should I start a new Activity or just change the data, and call Adapter.notifyDataSetChanged()?

It seems like calling notifyDataSetChanged() is simpler, and would minimize my potential number of activities (and memory usage), but I want the Up/Back navigation to work.

My app works like File Explorer where there is a list of folders, and clicking on a folder changes the list to show the contents of the new folder. If the user clicks on a folder, I want the Up/Back buttons to take them back to the prior folder. I have implemented this with a single instance of the activity and using notifyDataSetChanged(), but can't get the Up/Back buttons working as desired. I am thinking I need to either override those somehow, or use multiple instances of the same activity. Any direction here would be appreciated.

Thanks

Solution

Using multiple instances of the same Activity is highly unproductive.

To solve your problem, the best way to do it would be to use a fragment using multiple instances of it, each one representing a folder in your arborescence. Then in the onBackPressed() of your activity, you can just use popBackStack() while there is a fragment in the backStack, then call super.onBackPressed() to resume default behavior.

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Answered By - Bhullnatik