Is recreating a activity common sense

Question

In our application when a user switches between modes (different user/ different type of screen) the activity recreates itself (by an explicit call to recreate() ). This behavior was added by a external programmer we hired. He states this is completely normal to do.

The problem I have with this is that 99,9% of all activity state is the same. But when the activity is recreated all data is queried again, consuming quite a bit of time.

Is this a normal pattern? Or is it just as good to only change the data to suit the new situation?

when you say " switches between modes " you mean screen rotation? — Blackbelt, Mar 17 '14 at 14:16
It is somewhat normal to recreate activity when changing the Locale, so that new localization resources are loaded automatically by the Android system. — luben, Mar 17 '14 at 14:19
We're using an embedded device so screen rotation is not supported. We're also not chancing locales. — refro, Mar 17 '14 at 14:20

score 2 · Answer 1 · answered Mar 17 '14 at 14:23

To me it seems kind of strange to manually recreate the whole Activity just to reload some data. In any case just updating the data which has actually changed seems like a much better approach. Especially if you say that it takes quite a bit of time to reload all the data.

The only thing I can think of right now which requires to recreate the Activity is changing the locale or something like, but even that I would not recommend unless it is really necessary. If you are not dealing with configuration changes, e.g. locale, there is no reason to recreate the whole Activity just to reload some data.

score 0 · Answer 2 · edited May 23 '17 at 12:11

I would say it's "normal" in the sense that Activities are recreated all the time by the system, so this just adds another event in which that would happen. Though this is, on it's own, really weird way of going about it. A better, more efficient, cleaner way would be to swap out Fragments on "mode change". You can have a UI fragment for each "mode" and the data stored in a retained Fragment that each one pulls from. This would also help in the sense that the UI doesn't have to be recreated completely with each Fragment swap.

However, if you must, it is an absolute requirement that you follow the same data storage/retrieval methods that you would if the system was killing and recreating the Activity. See How to save state during orientation change in Android if the state is made of my classes?

Basically, you shouldn't be recreating data you already have.

Is recreating a activity common sense

2 Answers2