How to get last Fragment used when pressing back button

Question

I have a simple fragment with this code:

private BottomNavigationView.OnNavigationItemSelectedListener navListener =
            new BottomNavigationView.OnNavigationItemSelectedListener() {
                @Override
                public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
                    Fragment selectedFragment= null;

                    switch (menuItem.getItemId()){
                        case R.id.nav_home:
                            selectedFragment= new HomeFragment();
                            setTitle("Beranda");
                            break;
                        case R.id.nav_message:
                            selectedFragment= new MessageFragment();
                            setTitle("Pesan");
                            break;
                        case R.id.nav_transaction:
                            selectedFragment= new TransactionFragment();
                            setTitle("Transaksi");
                            break;
                        case R.id.nav_profile:
                            selectedFragment= new ProfileFragment();
                            setTitle("Profil");
                            if(sessionLevel.equals("admin")){
                                setTitle("Admin");
                            }
                            break;
                    }
                    getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, selectedFragment).commit();
                    return true;
                }
            };

Most of the fragment are just some kind of holder for Intent Activity. And the Activity itself doesnt have some fancy code.

The problem is that when i do Intent on Profile menu and then press back, the fragment shown is HomeActivity but the selected button is Profile . I dont know about the other 2 fragment since im not there yet, but probably they do the same thing.

Answer 1

You can do this like the following:

    @Override
        public void onBackPressed() {
            super.onBackPressed();

            Fragment frag = YourActivity.this.getSupportFragmentManager().findFragmentById(R.id.fragment_container);

           if(frag!=null && frag instanceof yourFragment)
           {}

   }

The following will give you count

int count = getSupportFragmentManager().getBackStackEntryCount();

You can make condition, If count is great than 1 then have more than 1 fragments else you have atleast 1 fragment and that will be last fragment. If count 0 then no more fragment available on stack as all have been poped out of stack.

Answer 2

1. Create an interface:

public interface IOnBackPressed {
    boolean onBackPressed();
}

2. In Fragment implement IOnBackPressed like:

public class FAQFragment extends Fragment implements IOnBackPressed {
    public boolean onBackPressed() {
        return false
    }
}

3. On Main Activity Backpress use

@Override
public void onBackPressed(){
     if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
          getSupportFragmentManager().popBackStack();
     } 
}