HomeAsUp disappear when screen rotation change in fragment

Question

I have a MainActivity in which I load different fragments (just one at the same time).

I have implemented HomeAsUp too, and it works well, but when I open a fragment, the back arrow appears at the left-top corner , but if I change the screen orientation, hamburger menu appears. I think that when activity is destroyed on the screen orientation change, the fragment backstack is also destroyed, how can i avoid this?

MAIN ACTIVITY

public class MainActivity extends AppCompatActivity
           implements NavigationView.OnNavigationItemSelectedListener {

    private HashMap<String, String> connectedUserDataMap;
    private FloatingActionButton fab;
    private TextView textAccountName;
    private ImageView profileImage;
    private Bitmap profileImageBitmap;
    private boolean doubleBackToExitPressedOnce = false;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if (savedInstanceState == null) {  //Main menu
            MainFragment fragment = new MainFragment();
            android.support.v4.app.FragmentTransaction fragmentTransaction =
                    getSupportFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.fragment_container, fragment);  
            fragmentTransaction.commit();

        }
   //listener onBackStackChangedListener
           getSupportFragmentManager().addOnBackStackChangedListener(new 
   FragmentManager.OnBackStackChangedListener() {
               @Override
               public void onBackStackChanged() {

                if (getSupportFragmentManager().getBackStackEntryCount() > 0) {

                    getSupportActionBar().setDisplayHomeAsUpEnabled(true); // show back button
                    toolbar.setNavigationOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            onBackPressed();
                        }
                    });
                } else {
                    //show hamburger
                    getSupportActionBar().setDisplayHomeAsUpEnabled(false);
                    toggle.syncState();
                    toolbar.setNavigationOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            drawer.openDrawer(GravityCompat.START);
                        }
                    });
                }
            }
        });
}

In the fragment I have nothing related to this issue to show, just a fragment

EDIT 1:

I am doing some System.out.printlns in the fragment

System.out.println("BACKSTACK COUNT =  
 "+getActivity().getSupportFragmentManager().getBackStackEntryCount());

I can see that getBackStackEntryCount() = 1 but the code in my MainActivity does not execute cause the backstack has not changed and does not print the back arrow

The Issue is that when I open the fragment the back arrow is at the left top corner, but when I rotate the screen, hamburger menu appears when It should not

SOLVED: I just put the code associated with the OnBackStackChangedListener in the MainActivity oncreate method too!

Thanks to all!

Answer 1

Have you tried adding

android:configChanges="orientation"

to your maifest in the activity tag for your activity not to be destroyed upon orientation change?

EDIT 1

Check this question it seems similar to your problem: Fragment Backstack is not restored when orientation changes

Answer 2

Try adding below line within your fragment's onCreate():

this.setRetainInstance(true);

It will retain the state even on rotation change. It will guarantee that the fragment does not get destroyed and recreated on orientation change