如何在抽屉布局（带导航抽屉菜单）中使用 Android 导航组件（导航图）？

Question

I have a navigation graph that uses this fragment as a home in the main activity XML.

        <fragment
        android:id="@+id/fragment_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        class="androidx.navigation.fragment.NavHostFragment"
        app:navGraph="@navigation/main_nav_graph"
        app:defaultNavHost="true"/>

I have a Drawer layout with a menu , I can't manage to make the navigation to work when I click on the navigation drawer button (it works from main fragment but not when I click on Drawer buttons), If I use the old way to program the navigation drawer using : getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new_fragment).commit(); , my navcontroller is lost!! and I get errors like

destination fragment in unknown by navcontroller , because the controller will see the home fragment as currently displayed even if it is not the case (from debug)

public boolean onNavigationItemSelected(MenuItem item) {

        switch (item.getItemId()){
            case R.id.action_1:
                //doesn't work when it current fragment doesnt match the 
                //action_fromfragmentx_to_fragmenty
                Navigation.findNavController(this,R.id.fragment_container)
                .navigate(R.id.action_fromfragmentx_to_fragmenty);
                break;

            //Other menu options...
        }

Hence my question : How should I override this onNavigationItemSelected in Java to make the navigation component work? any link or relative doc about this subject(in Java) ?.

Answer 1

The Navigation component offers a helper class in NavigationUI in the navigation-ui artifact. As per the Update UI components with Navigation documentation for navigation drawers , you can use the setupWithNavController() method to automatically hook up menu items to navigation destinations you set up in your navigation graph by tying the destination item to a menu item :

If the id of the MenuItem matches the id of the destination, the NavController can then navigate to that destination.

Therefore you don't need a onNavigationItemSelected implementation at all, nor do you need to do any FragmentTransactions. Just make sure that the android:id="@+id/fragment_y" in your menu XML matches the android:id="@+id/fragment_y" in your navigation XML and call setupWithNavController() :

NavigationView navView = findViewById(R.id.nav_view);
// This is what sets up its own onNavigationItemSelected
NavigationUI.setupWithNavController(navView, navController);