Hide android bottom navigation view for child screens/ fragments

Question

I'm trying to create a single activity Android application. I have MainActivity (only activity) with BottomNavigationView, three top level fragments and some child fragments. My requirement is whenever the screen is showing top level fragments, bottom navigation should be visible such that switching is possible. But when I'm viewing any of the child fragments, bottom navigation should be hidden. Is there any out-of-box way using the Navigation component or need to change the visibility manually ?

Answer 1

Update (Navigation component 1.0)

As of Navigation component 1.0.0-alpha08, method addOnNavigatedListener(controller: NavController, destination: NavDestination) was changed to addOnDestinationChangedListener(controller: NavController, destination: NavDestination, arguments: Bundle). Its behavior was also slightly changed (it is also called if the destinations arguments change).

Old Answer

You can use NavController.OnNavigatedListener to achieve this behavior (set it in Activity onCreate):

findNavController(R.id.container).addOnNavigatedListener { _, destination ->
    when (destination.id) {
        R.id.dashboardFragment -> showBottomNavigation()
        else -> hideBottomNavigation()
    }
}

private fun hideBottomNavigation() {
    // bottom_navigation is BottomNavigationView
    with(bottom_navigation) {
        if (visibility == View.VISIBLE && alpha == 1f) {
            animate()
                    .alpha(0f)
                    .withEndAction { visibility = View.GONE }
                    .duration = EXIT_DURATION
        }
    }
}

private fun showBottomNavigation() {
    // bottom_navigation is BottomNavigationView
    with(bottom_navigation) {
        visibility = View.VISIBLE
        animate()
                .alpha(1f)
                .duration = ENTER_DURATION
    }
}