Show Back Arrow in Fragment

Question

I want to show Back Arrow in Fragments ToolBar. Im trying to write this code: ((AppCompatActivity) getActivity()).getSupportActionBar().setDisplayHomeAsUpEnabled(true);

but AS writes: method invokation .. may produce "java.lang.NullPointerException". What about getSupportActionBar(), AS writes cannot resolve method. Whats wrong? Here is my code:

public class AddFilterFrag extends android.app.Fragment  {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);       
        setHasOptionsMenu(true);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.add_filter_layout, container, false);
        ((AppCompatActivity) getActivity()).getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        return rootView;
    }
 @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        super.onCreateOptionsMenu(menu, inflater);

       inflater.inflate(R.menu.fragment_menu, menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == android.R.id.home) {
            //something to do
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

user_9802543 · Answer

while using navigation graphs use navController to do that

On the activity thats holding the host fragment do this

lateinit var navController : NavController

In oncreateView

navController = this.findNavController(R.id.nav_host_fragment)
        NavigationUI.setupActionBarWithNavController(this, navController)

override onSupportNavigateUp

override fun onSupportNavigateUp(): Boolean {
        return navController.navigateUp()
    }

that handles the up arrow by itself.

Show Back Arrow in Fragment

4 Answers