In the [example](http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.html) on using fragments in the Android docs, when the application is in 'dualview' mode, the details fragment is recreated whenever the application needs to show details for a different title. `FragmentTransaction.replace()` is used to swap out each old details fragment instance with a new one.

Is this recommended practice? Isn't it wasteful to create a new UI instance when the real intent (no pun intended) is to update what the UI shows, not the UI itself. It seems to me the only reason to create new instances is if one intends to add them to the backstack so the user can retrace steps. Otherwise, is it safe/advisable to update a fragment directly?

In the case of the example, it would mean a method along the lines of `DetailsFragment.setShownIndex()`. This would be called, passing in the new title index, instead of recreating `DetailsFragment`. 

Suppose we have a version of the example where one activity manages both fragments, but only shows one at a time, swapping each fragment out as needed. Would it be ok for the activity to create an instance of each fragment, retain references to each, and then simply add or remove these two instances from itself as needed? 

One possibly sticky consequence of this would be that, when the titles fragment is in `resumed` state (i.e. in the 'foreground'), selecting a title will result in a call to `DetailsFragment.setShownIndex()` at a time when the details fragment is in `stopped` state. 

Good idea? Bad idea?

Thanks in advance.