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When I navigate from one Fragment to another with the new Navigation Components, I can do it successfully with the following:

btn_walk.setOnClickListener(Navigation.createNavigateOnClickListener(R.id.next_action))

Now, if I pop the backstack from the destination Fragment with

findNavController().popBackStack()

The Fragment that launched that Fragments recreates itself again, but the state is not being saved, I have been looking around to see how to fix it, but I don't really know if actually how to do an .add function with the navigate() from Navigation components

enter image description here

This gif shows the navigation from one fragment to another, when popping the stack from the destination fragment, it recreates the fragment that launched that one instead of saving the state of it.

Using the fragmenttransaction.add() method does maintain the instance of that fragment alive also if I pop the back stack.

Is there any way to do the same with Navigation Components ?

I have also readed this Navigation Architecture Fragment Reload Problem but it's unclear how it should be solved.

halfer
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Gastón Saillén
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1 Answers1

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Fragments automatically restore their saved state when they return from the back stack: that is true with our without Navigation. Seems like the problem is with how you've coded your Fragment.

You can confirm this is a problem with your Fragment by turning on 'Don't keep activities', hitting the home button, then returning to your app and see if the Fragment restores its state perfectly. You can also test the case where you handle configuration changes (i.e., rotating the device) correctly - again, you should be able to restore your state exactly where you were. If you handle both those cases, then it'll work great in Navigation as well.

ianhanniballake
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  • I'd strongly suggest asking separate questions if you have a specific View, etc. that you're having difficult with in saving/restoring its state in either of those cases. – ianhanniballake Jul 24 '19 at 02:32
  • Thanks Ian, Will take a look tomorrow – Gastón Saillén Jul 24 '19 at 04:49
  • His question is actually legitimate. It's a navigation component bug, and it's being discussed here. https://stackoverflow.com/questions/50485988/is-there-a-way-to-keep-fragment-alive-when-using-bottomnavigationview-with-new-n/51684125#51684125 there is also a bug report https://issuetracker.google.com/issues/80029773 – TatiOverflow Mar 03 '21 at 16:39
  • @TatiOverflow - no, that has nothing to do with this issue. Fragments **on the back stack** already save and restore their state properly. That issue link is specifically for fragments **not** on the back stack. – ianhanniballake Mar 03 '21 at 17:24