旨在显示带有 3 个菜单的底部栏（每个菜单都有专用片段）。尽管相同的预览完全位于片段下方，但 BottomBar 不会显示在 UI 中。粘贴在下面的 HomeActivity 的 AndroidStudio 屏幕截图。
由于大多数示例都使用 CoordinatedLayout，因此 ConstraintLayout 是否有任何限制？
<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:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".home.HomeActivity">
<fragment
android:id="@+id/nav_host_home_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="0dp"
app:defaultNavHost="true"
app:layout_constraintBottom_toTopOf="@id/bottomNavigationView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="@navigation/nav_home" />
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/bottomNavigationView"
style="@style/Widget.MaterialComponents.BottomNavigationView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?android:attr/windowBackground"
app:itemIconTint="@color/colorPrimary"
app:itemTextColor="@color/colorPrimary"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="@menu/bottom_home_menu" />
</androidx.constraintlayout.widget.ConstraintLayout>
并在 HomeActivity 中设置 BottomBar，如下所示：
private fun setupNavigation() {
val navController = findNavController(R.id.nav_host_home_fragment)
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
val appBarConfiguration = AppBarConfiguration(
setOf(
R.id.navigation_home, R.id.navigation_bookings, R.id.navigation_profile
)
)
setupActionBarWithNavController(navController, appBarConfiguration)
bottomNavigationView.setupWithNavController(navController)
}