如何制作一个深度片段以在屏幕上使用喷气背包导航和BottomNavigationView来占据整个屏幕？

Question

I study the google example at https://github.com/android/architecture-components-samples/tree/master/NavigationAdvancedSample .And it works like this :

But I need the about fragment to take the whole screen.What is best practice?

I have try this : activity?.supportFragmentManager?.beginTransaction()?.replace(R.id.root_activity,Detail())?.addToBackStack("About")?.commit()

and get this:

the activity_main.xml:

<LinearLayout 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:id="@+id/root_activity"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.example.android.navigationadvancedsample.MainActivity">

<androidx.fragment.app.FragmentContainerView
    android:id="@+id/nav_host_container"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1" />

<com.google.android.material.bottomnavigation.BottomNavigationView
    android:id="@+id/bottom_nav"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom"
    app:menu="@menu/bottom_nav"/>

I can set activity?.findViewById<BottomNavigationView>(R.id.bottom_nav)?.visibility=View.GONE or activity?.findViewById<BottomNavigationView>(R.id.bottom_nav)?.visibility=View.INVISIBLE But when it comes back,it looks like this,I think this is not good way:

thanks!!

Answer 1

You have to toggle visibility of BottomNavigationView as shown below:

NavController.OnDestinationChangedListener destinationChangedListener = new NavController.OnDestinationChangedListener() {
        @Override
        public void onDestinationChanged(@NonNull NavController controller, @NonNull NavDestination destination, @Nullable Bundle arguments) {
            if(destination.getId() == R.id.navigation_notifications){
                navView.setVisibility(View.GONE);
            }else{
                navView.setVisibility(View.VISIBLE);
            }

        }
    };
    navController.addOnDestinationChangedListener(destinationChangedListener); 

Answer 2

in case anybody has ths same question,I post my answer here.

to work around ,I put BottomNavigationView into a MainFragment instead of MainActivity . And in the MainActivity dynamically instantiate the MainFragment,so I can replace the MainFragment as a whole in my deep child fragment .

class MainActivity : AppCompatActivity() {

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val container = FrameLayout(this)
    container.id = R.id.activity_container
    setContentView(container)
    supportFragmentManager.beginTransaction().replace(R.id.activity_container,MainFragment()).commit()
}

}

in the nested fragment : activity?.supportFragmentManager?.beginTransaction()?.replace(R.id.activity_container,About())?.addToBackStack("Abouts")?.commit()

final effect(have strip away the toolbar):