Stop fragment refresh in bottom nav using navhost

Question

This problem has been asked a few times now, but we are in 2020 now, did anyone find a good usable solution to this yet?

I want to be able to navigate using the bott

Answer 1

The simple solution to stop refreshing on multiple clicks on the same navigation item could be

 binding.navView.setOnNavigationItemSelectedListener { item ->
        if(item.itemId != binding.navView.selectedItemId)
            NavigationUI.onNavDestinationSelected(item, navController)
        true
    }

where binding.navView is the reference for BottomNavigationView using Android Data Binding.

Answer 2

create a class:

@Navigator.Name("keep_state_fragment") // `keep_state_fragment` is used in navigation xml 
class KeepStateNavigator(
private val context: Context,
private val manager: FragmentManager, // Should pass childFragmentManager.
private val containerId: Int
) : FragmentNavigator(context, manager, containerId) {

override fun navigate(
    destination: Destination,
    args: Bundle?,
    navOptions: NavOptions?,
    navigatorExtras: Navigator.Extras?
): NavDestination? {
    val tag = destination.id.toString()
    val transaction = manager.beginTransaction()

    var initialNavigate = false
    val currentFragment = manager.primaryNavigationFragment
    if (currentFragment != null) {
        transaction.detach(currentFragment)
    } else {
        initialNavigate = true
    }

    var fragment = manager.findFragmentByTag(tag)
    if (fragment == null) {
        val className = destination.className
        fragment = manager.fragmentFactory.instantiate(context.classLoader, className)
        transaction.add(containerId, fragment, tag)
    } else {
        transaction.attach(fragment)
    }

    transaction.setPrimaryNavigationFragment(fragment)
    transaction.setReorderingAllowed(true)
    transaction.commitNow()

    return if (initialNavigate) {
        destination
    } else {
        null
    }
}
}

Use keep_state_fragment instead of fragment in nav_graph

In Activity:

val navController = findNavController(R.id.nav_host_fragment)

    // get fragment
    val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment)!!
    // setup custom navigator
    val navigator = KeepStateNavigator(this, navHostFragment.childFragmentManager, R.id.nav_host_fragment)
    navController.navigatorProvider += navigator

    // set navigation graph
    navController.setGraph(R.navigation.nav_graph)
    bottom_navigation.setupWithNavController(navController)