How to get Back Button in Actionbar with new Jetpack navigation

Question

I want to have a Backbutton in the default Actionbar on an new androidx jetpack navigation App.

I follow the google navigation-getting-started to build a navigation app, but I'm missing a Backbutton in the Actionbar so I add in the OnCreate of the MainActivity:

        ActionBar actionbar = getSupportActionBar();
        NavController nc = Navigation.findNavController(mainFragment.getView());
        AppBarConfiguration appBarConfiguration = new AppBarConfiguration.Builder(nc.getGraph()).build();
        androidx.navigation.ui.NavigationUI.setupActionBarWithNavController(this,nc, appBarConfiguration); 

Now I see a Backbutton in the ActionBar if I'm not in the start main fragment, but there is no back function if I tap that button. The regular back-key works fine, but how do I get the actionbar backbutton to work.

Update: It is not working from second fragment to first(main/root) fragment. from third to second fragment it is working. nav-graph

Answer 1

try this :-

toolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //do your stuff here
            }
        });

second option is;-

@Override
    public boolean onSupportNavigateUp() {
        return super.onSupportNavigateUp();
        // do your stuff here
    }