hey! I’m playing with BottomNavigation and Jetpack...

# compose

[nglauber]

hey! I’m playing with BottomNavigation and Jetpack Navigation and I did an sample based on @Afzal Najam post ( thanks man🙏 https://afzaln.com/multiple-navigation-graphs-with-jetpack-compose-navigation/)
Here’s my code:
https://gist.github.com/nglauber/5061cbbafd63488131380b09c8943ad7
I have two questions:
1. When the second tab is selected and displaying its root content, is there a way to display the first tab when the user presses the system back key?
2. Could someone point out where can I find a way to save the LazyColumn scroll position? In my sample, the first tab is a list.

[nglauber]

ok. I fixed #2 hoisting rememberLazyListState()

[Afzal Najam]

I think if you want to display the first tab with the back button, you might want to put both tabs in a single nav graph. The second tab wouldn't need its own nav graph in this use case, right?

[nglauber]

I tried the approach presented in documentation sample… but when I use a single nav graph and reselect the first tab, I missed the first tab back stack. Only the root composable of the first tab is displayed.

[nglauber]

Another idea I had was: set a NavHost as a child of Scaffold, and the NavHost has two other `NavHost`’s inside of it (one for each tab)… But didn’t work 😕

[Karthick]

May listen to back button click and do your logic manually

[nglauber]

@Karthick I guess this should the simpler way to deal with this specific case… But I’m wondering why NavHost is not working with nested `NavHost`s… 🤔

[Afzal Najam]

Nelson, there's a new way to deal with nested nav graphs. I'm not sure it's in the documentation yet but it's in the Androidx samples.

https://github.com/androidx/androidx/blob/androidx-main/navigation/navigation-compose/samples/src/main/java/androidx/navigation/compose/samples/NavigationSamples.kt

https://github.com/androidx/androidx/blob/androidx-main/navigation/navigation-compose/integration-tests/navigation-demos/src/main/java/androidx/navigation/compose/demos/NestedNavDemo.kt

[Kshitij Patil]

I had similar requirement and I implemented self navigation for the fragment hosting the BottomNavigation as launching the same fragment will ultimately start with First Tab but you'll lose all the navgraph states with this approach

[nglauber]

yeah… I’m having this same result @Kshitij Patil 😕
Basically, to summarize, I want to simulate the same navigation approach used by YouTube.

[nglauber]

It worked! 🎉
Thanks to this code by @Vinay Gaba 👏
https://github.com/airbnb/Showkase/blob/9301d3dc49fa3174b813931a332d56c5565ea8ad/showkase/src/main/java/com/airbnb/android/showkase/ui/BackButtonHandler.kt

[nglauber]

[Yahor]

Two navigation graphs can solve the issue #1

https://github.com/egorikftp/BelarusResistanceFlag

[nglauber]

I did that 😉 thanks @Yahor