NavController navController;
AppBottomBar navView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    navView = findViewById(R.id.nav_view);

    Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.nav_host_fragment);
    navController = NavHostFragment.findNavController(fragment);
    NavGraphBuilder.build(this, fragment.getChildFragmentManager(), navController, fragment.getId());

    navView.setOnNavigationItemSelectedListener(this);
}

@Override
public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
    navController.navigate(menuItem.getItemId());
    return !TextUtils.isEmpty(menuItem.getTitle());
}

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app=“http://schemas.android.com/apk/res-auto"
android:id=”@+id/container"
android:layout_width=“match_parent"
android:layout_height=“match_parent"
android:paddingTop=”?attr/actionBarSize”>

<fragment
    android:id="@+id/nav_host_fragment"
    android:name="androidx.navigation.fragment.NavHostFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:defaultNavHost="true"
    app:layout_constraintBottom_toTopOf="@id/nav_view"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

<com.guoanrui.mynavigation.view.AppBottomBar
    android:id="@+id/nav_view"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginStart="0dp"
    android:layout_marginEnd="0dp"
    android:background="?android:attr/windowBackground"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>
老师您好，总是报这个故障，你帮我看下问题出在哪里那