Fragment re-created on bottom navigation view item selected

Question

Following is my code for bottom navigation view item selected

bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationI         


        

Answer 1

This seemed to work well for me. Instead of attaching and detaching, i use show or hide to maintain fragment state.

    public void changeFragment(Fragment fragment, String tagFragmentName) {

        FragmentManager mFragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = mFragmentManager.beginTransaction();

        Fragment currentFragment = mFragmentManager.getPrimaryNavigationFragment();
        if (currentFragment != null) {
            fragmentTransaction.hide(currentFragment);
        }

        Fragment fragmentTemp = mFragmentManager.findFragmentByTag(tagFragmentName);
        if (fragmentTemp == null) {
            fragmentTemp = fragment;
            fragmentTransaction.add(R.id.frame_layout, fragmentTemp, tagFragmentName);
        } else {
            fragmentTransaction.show(fragmentTemp);
        }

        fragmentTransaction.setPrimaryNavigationFragment(fragmentTemp);
        fragmentTransaction.setReorderingAllowed(true);
        fragmentTransaction.commitNowAllowingStateLoss();
    }

And this is how i use it

     private void initViews() {
        BottomNavigationView bottomNavigationView = findViewById(R.id.navigation);
        bottomNavigationView.setOnNavigationItemSelectedListener
                (new BottomNavigationView.OnNavigationItemSelectedListener() {
                    @Override
                    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                        Fragment selectedFragment = null;
                        switch (item.getItemId()) {
                            case R.id.explore:
                                changeFragment(new ExploreFragment(), ExploreFragment.class
                                        .getSimpleName());
                                toggleViews(true, "");
                                break;
                            case R.id.favorite:
                                changeFragment(new FavoriteFragment(), FavoriteFragment.class
                                        .getSimpleName());
                                toggleViews(false, "Favorites");
                                break;
                            case R.id.venue:
                                changeFragment(new VenueFragment(), VenueFragment.class.getSimpleName());
                                toggleViews(false, "Venues");
                                break;
                            case R.id.profile:
                                changeFragment(new ProfileFragment(), ProfileFragment.class
                                        .getSimpleName());
                                toggleViews(false, "Profile");
                                break;
                        }
                        return true;
                    }
                });

        //Manually displaying the first fragment - one time only
        changeFragment(new ExploreFragment(), ExploreFragment.class
                .getSimpleName());

    }