我找不到任何使用androidx导航体系结构的java示例，用于使用底部导航的单个活动

implementation 'androidx.navigation:navigation-fragment:2.3.5'
implementation 'androidx.navigation:navigation-ui:2.3.5'

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

<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/navigation_home"
        android:title="Home"
        android:icon="@drawable/ic_home" />
    <item
        android:id="@+id/navigation_dashboard"
        android:title="Dashboard"
        android:icon="@drawable/ic_dashboard" />
    <item
        android:id="@+id/navigation_notifications"
        android:title="Notifications"
        android:icon="@drawable/ic_notifications" />
</menu>

import androidx.appcompat.app.AppCompatActivity;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.AppBarConfiguration;
import androidx.navigation.ui.NavigationUI;

public class MainActivity extends AppCompatActivity {

    private NavController navController;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        BottomNavigationView bottomNavigationView = findViewById(R.id.bottomNavigationView);
        navController = Navigation.findNavController(this, R.id.nav_host_fragment);

        AppBarConfiguration appBarConfiguration = new AppBarConfiguration.Builder(
                R.id.navigation_home, R.id.navigation_dashboard, R.id.navigation_notifications)
                .build();

        NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration);
        NavigationUI.setupWithNavController(bottomNavigationView, navController);
    }

    @Override
    public boolean onSupportNavigateUp() {
        return NavigationUI.navigateUp(navController, appBarConfiguration)
                || super.onSupportNavigateUp();
    }
}