Remove up button from action bar when navigating using BottomNavigationView with Android Navigation UI library

Question

I\'ve created a small app that has three fragments for top-level navigation through a BottomNavigationView. If you launch the app and click on a navigation button on the bottom

Answer 1

I had the same problem and I found a way to get the current fragment with the NavController.addOnNavigatedListener, so I applied the following logic within my Activity and for now it works for me

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_home)
    val navHost = supportFragmentManager
            .findFragmentById(R.id.navHostFragment) as NavHostFragment

    navHost.navController.addOnNavigatedListener { _, destination ->
        val showButton = showUpButton(destination.id)
        //Here occurs the magic
        supportActionBar?.setDisplayShowHomeEnabled(showButton)
        supportActionBar?.setDisplayHomeAsUpEnabled(showButton)
    }
}

//Check according to your convenience which fragment id
//should show or hide the "Up Button"
private fun showUpButton(id: Int): Boolean {
    return id != R.id.your_home_fragment && id != R.id.your_list_fragment 
            && id != R.id.your_profile_fragment
}

And this is my project...

I do not know if it is the best option but if someone has any better suggestion, it will be welcome