MainActivity.kt

fun setupViews()
{
    // Finding the Navigation Controller
    var navController = findNavController(R.id.fragNavHost)

    // Setting Navigation Controller with the BottomNavigationView
    bottomNavView.setupWithNavController(navController)

    // Setting Up ActionBar with Navigation Controller
    // Pass the IDs of top-level destinations in AppBarConfiguration
    var appBarConfiguration = AppBarConfiguration(
        topLevelDestinationIds = setOf (
            R.id.homeFragment,
            R.id.searchFragment,
            R.id.notificationsFragment,
            R.id.profileFragment
        )
    )
    setupActionBarWithNavController(navController, appBarConfiguration)
}