So I'm trying to build an app with a bottom navigation bar that will switch between fragments. I did the coding according to some documentation.
I tried every solution on the internet but none of them seems to work for me.
the error:
Caused by: java.lang.ClassCastException: com.example.jetpacklesson.MainFragment cannot be cast to androidx.navigation.fragment.NavHostFragment
at com.example.jetpacklesson.MainActivity.onCreate(MainActivity.java:30)
here is the XML main activity code
<androidx.constraintlayout.widget.ConstraintLayout 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=".MainActivity">
<androidx.fragment.app.FragmentContainerView
android:id="@ id/firstFragmentHolder"
android:layout_width="0dp"
android:layout_height="0dp"
android:name="com.example.jetpacklesson.MainFragment"
app:defaultNavHost = "true"
app:layout_constraintBottom_toTopOf="@ id/bnv_bottomBar"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph = "@navigation/nav_graph"/>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@ id/bnv_bottomBar"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:menu="@menu/nav_bottom_navigation" />
</androidx.constraintlayout.widget.ConstraintLayout>
and main activity java code:
BottomNavigationView bnv_navigationBar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.firstFragmentHolder);
NavController navController = navHostFragment.getNavController();
bnv_navigationBar = findViewById(R.id.bnv_bottomBar);
NavigationUI.setupWithNavController(bnv_navigationBar, navController);
}
CodePudding user response:
Your XML file says:
android:name="com.example.jetpacklesson.MainFragment"
If you want that to be a NavHostFragment
, you need to change that to
android:name="androidx.navigation.fragment.NavHostFragment"
As per the Navigation Getting Started guide.