kotlin.TypeCastException: null cannot be cast to non-null type androidx.navigation.fragment.NavHostFragment at NavigationExtensionsKt

Issue

I copied the NavigationExtensions.kt extension file from the NavigationAdvancedSample and I get this exception:

Solution

UPDATE: make sure your menu item ids are the same as your navigation resource files ids

also: if you're having a problem with ItemReselectedListener Add null safety checks, your listener should be something like this:

setOnNavigationItemReselectedListener { item ->
        val newlySelectedItemTag = graphIdToTagMap[item.itemId]
        val selectedFragment = fragmentManager.findFragmentByTag(newlySelectedItemTag)
                as NavHostFragment?
        val navController = selectedFragment?.navController
        // Pop the back stack to the start destination of the current navController graph
        navController?.popBackStack(
            navController.graph.startDestination, false
        )
    }

Answered By - tahaak97