BottomNavigationView and Android Navigation not switching fragments

Question

I am trying to use a BottomNavigationView with Android Navigation to create a standard tabbed application with three fragments: StatusFragment, MapFragment, and AlertsFragment.

I have my main_activity.xml with a FragmentContainerView and BottomNavigationView defined as follows:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.main.MainActivity">

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/mainNavHostFragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toTopOf="@id/bottomNavigationView"
        app:defaultNavHost="true"
        app:navGraph="@navigation/main_nav_graph" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottomNavigationView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:menu="@menu/main_menu" />

</androidx.constraintlayout.widget.ConstraintLayout>

My main_nav_graph.xml:

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main_nav_graph"
    app:startDestination="@id/mainActivity">
    <fragment
        android:id="@+id/statusFragment"
        android:name="<redacted>.ui.status.StatusFragment"
        android:label="StatusFragment" />
    <fragment
        android:id="@+id/mapFragment"
        android:name="<redacted>.ui.map.MapFragment"
        android:label="MapFragment" />
    <fragment
        android:id="@+id/alertsFragment"
        android:name="<redacted>.ui.alert.AlertsFragment"
        android:label="AlertsFragment" />
    <activity
        android:id="@+id/mainActivity"
        android:name="<redacted>.ui.main.MainActivity"
        android:label="main_activity"
        tools:layout="@layout/main_activity" />
</navigation>

And the associated main_menu.xml:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/statusFragment"
        android:icon="@drawable/ic_status_24"
        android:title="@string/title_status" />
    <item
        android:id="@+id/mapFragment"
        android:icon="@drawable/ic_map_24"
        android:title="@string/title_map" />
    <item
        android:id="@+id/alertsFragment"
        android:icon="@drawable/ic_alert_24"
        android:title="@string/title_alerts" />

</menu>

In the onCreate method of my MainActivity, I configure navigation as follows:

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.main_activity)
        binding = MainActivityBinding.inflate(layoutInflater)
        val navHostFragment = supportFragmentManager.findFragmentById(R.id.mainNavHostFragment) as NavHostFragment
        val navController = navHostFragment.navController

        val appBarConfiguration = AppBarConfiguration(
            setOf(
                R.id.statusFragment,
                R.id.mapFragment,
                R.id.alertsFragment
            )
        )

        NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration)
        NavigationUI.setupWithNavController(binding.bottomNavigationView, navController)
    }

The tab bar is displayed as expected, but tapping on the buttons does not do anything. I've made sure that the ids defined in main_menu.xml match those in main_nav_graph.xml. For being such a basic component of navigation on mobile, getting this to work on Android is proving to be frustratingly difficult; any help would be greatly appreciated.

Answer 1

Had the same error. What fixed it is using the same id for the fragments in the menu and navgraph xml files. menu:

<item
    android:id="@+id/navigation_home"
    android:icon="@drawable/ic_home"
    android:title="@string/home" />

<item
    android:id="@+id/navigation_explore"
    android:icon="@drawable/ic_explore"
    android:title="@string/explore" />

<item
    android:id="@+id/navigation_post"
    android:icon="@drawable/ic_post"
    android:title="@string/post" />

<item
    android:id="@+id/navigation_notifications"
    android:icon="@drawable/ic_notifications"
    android:title="@string/notifications" />

<item
    android:id="@+id/navigation_messages"
    android:icon="@drawable/ic_messages"
    android:title="@string/messages" />

navigation:

<fragment
    android:id="@+id/navigation_home"
    android:name="com.simpleapps22.dholuo.ui.home.HomeFragment"
    android:label="@string/home"
    tools:layout="@layout/fragment_home" />
<fragment
    android:id="@+id/navigation_explore"
    android:name="com.simpleapps22.dholuo.ui.explore.ExploreFragment"
    android:label="@string/explore"
    tools:layout="@layout/fragment_explore"/>
<fragment
    android:id="@+id/navigation_post"
    android:name="com.simpleapps22.dholuo.ui.post.PostFragment"
    android:label="@string/post"
    tools:layout="@layout/fragment_post"/>
<fragment
    android:id="@+id/navigation_notifications"
    android:name="com.simpleapps22.dholuo.ui.notifications.NotificationsFragment"
    android:label="@string/notifications"
    tools:layout="@layout/fragment_notifications" />
<fragment
    android:id="@+id/navigation_messages"
    android:name="com.simpleapps22.dholuo.ui.messages.MessagesFragment"
    android:label="@string/messages"
    tools:layout="@layout/fragment_messages" />

Answer 2

In My Case, I used ViewPager2 and connect it with BottomNavigationView using OnPageChangeCallback().

MainActivity.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity6">

    <androidx.viewpager2.widget.ViewPager2
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/viewpager"
        android:layout_above="@+id/bottom_navigation"/>

    <LinearLayout
        android:id="@+id/bottom_navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true">
        <com.google.android.material.bottomnavigation.BottomNavigationView
            android:id="@+id/bottom"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:menu="@menu/bottom_menu"
            app:itemIconTint="@color/custom_bottom"
            app:itemTextColor="@color/custom_bottom"
            android:background="@color/black"/>
    </LinearLayout>


</RelativeLayout>

ViewPagerAdapter : (I Used FragmentStateAdapter(fragmentActivity FragmentActivity) Because FragmentPagerAdapter is depecrated)

class ViewPagerAdapter(fragmentActivity: FragmentActivity): FragmentStateAdapter(fragmentActivity){

    override fun getItemCount(): Int {
        return 3
    }

    override fun createFragment(position: Int): Fragment {
        return when(position){
            0 -> {
                HomeFragment()
            }
            1 -> {
                HomeFragment2()
            }
            2 -> {
                HomeFragment3()
            }
            else -> {
                throw Resources.NotFoundException("Position Not Found")
            }
        }
    }
}

And Now I will show u the answer of ur question Note I used binding just to replace findByViewId MainActivity.kt:

class MainActivity6 : AppCompatActivity() {

    private lateinit var binding: ActivityMain6Binding
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMain6Binding.inflate(layoutInflater)
        val view = binding.root
        setContentView(view)

        setupBottom()
    }

    private fun setupBottom(){
        binding.viewpager.adapter = ViewPagerAdapter(this)
        binding.viewpager.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback(){
            override fun onPageSelected(position: Int) {
                super.onPageSelected(position)
                when(position){
                    0 -> {
                        binding.bottom.menu.findItem(R.id.page_1).isChecked = true
                    }
                    1 -> {
                        binding.bottom.menu.findItem(R.id.page_2).isChecked = true
                    }
                    2 -> {
                        binding.bottom.menu.findItem(R.id.page_3).isChecked = true
                    }
                }
            }
        })
        binding.bottom.setOnItemSelectedListener { item ->
            when(item.itemId){
                R.id.page_1 -> {
                    binding.viewpager.currentItem = 0
                    true
                }
                R.id.page_2 -> {
                    binding.viewpager.currentItem = 1
                    true
                }
                R.id.page_3 -> {
                    binding.viewpager.currentItem = 2
                    true
                }
                else -> false
            }
        }
    }

    // If the user is currently looking at the first step, allow the system to handle the
    // Back button. This calls finish() on this activity and pops the back stack.
    override fun onBackPressed() {
        if(binding.viewpager.currentItem == 0){
           super.onBackPressed()
        }
        else {
            // Otherwise, select the previous step.
            binding.viewpager.currentItem = binding.viewpager.currentItem - 1
        }
    }
}

Answer 3

Regarding the <fragment> Tag: Unfortunately, both current answers are wrong and it is actually discouraged by Google! Stop using the <fragment> tag. It is deprecated and will not be maintained anymore. You are correct to switch to <FragmentContainerView> which on top contains some lifecycle fixes that are not available in <fragment>

Your code looks almost perfect and I am pretty sure that it is not the navigation components, but the way you inflate the binding.

That said, here is a working code sample from one of my apps. Take special care that you:

• create the Binding using the DataBindingUtil

• set the desired fragment as startDestination this one was correctly spotted by @sercan!

• give you <navigation> element an id (not mandatory, but to be safe)

• use exactly the same imports! androidx.* everywhere, but material.bottomnavigation.BottomNavigtaionView.

• the id of the menu item must match exactly the id of the fragment in the navi graph (you already mentioned that in your question. But I still add it here for completness.)

• the FragmentContainerView really is the defaultNavHost for the given Activity.

activity_main.xml

<androidx.fragment.app.FragmentContainerView
    android:id="@+id/activity_repository_nav_host"
    android:name="androidx.navigation.fragment.NavHostFragment"
    app:defaultNavHost="true"
    app:navGraph="@navigation/nav_graph_repository" />

<com.google.android.material.bottomnavigation.BottomNavigationView
    android:id="@+id/activity_repository_bottom_nav"
    app:menu="@menu/menu_repo_bottom" />

ActivityRepository

import androidx.databinding.DataBindingUtil
import androidx.navigation.NavController
import androidx.navigation.fragment.NavHostFragment
import androidx.navigation.ui.setupWithNavController
import com.google.android.material.bottomnavigation.BottomNavigationView

private lateinit var navView: BottomNavigationView

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    
    DataBindingUtil.setContentView<ActivityRepositoryBinding>(this, R.layout.activity_repository).also { binding ->
        binding.lifecycleOwner = this
        binding.repositoryViewModel = repositoryViewModel
        binding.webHookViewModel = webHookViewModel
    }

    setupNavController()
}

private fun setupNavController() {
    val navHostFragment = supportFragmentManager.findFragmentById(R.id.activity_repository_nav_host) as NavHostFragment
    val navController = navHostFragment.navController
    
    navView = findViewById(R.id.activity_repository_bottom_nav)
    NavigationUI.setupWithNavController(navView, navController)
}

nav_graph_repository.xml

<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/navigation_graph"
app:startDestination="@+id/fragment_downloads">

    <fragment
    android:id="@+id/fragment_downloads"
    android:name="net.onefivefour.android.bitpot.screens.downloads.DownloadsFragment"
    android:label="@string/downloads"
    tools:layout="@layout/fragment_downloads" />

</navigation>

menu_repo_bottom.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

   ...
   <item
    android:id="@+id/fragment_downloads"
    android:icon="@drawable/ic_downloads"
    android:title="@string/downloads" />

</menu>

Answer 4

If still relevant, here is the solution: https://github.com/Codeveyor/Android-Tab-Bar Fully customizable, flexible, and easy to maintain. Run test project on device or emulator to check if it matches your expectations