ViewPager Fragement OncreateView called multiple times based on number of tabs switched

Question

I am having trouble with below code, i have 5 tabs in my application and when i am trying to switch through them i just noticed that onCreateView is called multiple times. Now first i did saw multiple post about similar issue where multiple times onCreateView is called, but mine is lit bit different, in my application onCreateView is called based on number of tabs i am switching. For example if i am DOWNLOAD tab and i switch to FAVORITE, onCreateView will be called 3 times. If i do same action from settings it will be called 4 times. Same thing happens with CANDIDATE and other tab.

Similar Posts -

1 - OnCreateView called multiple times / Working with ActionBar and Fragments

2 - Android fragment OnCreateView called twice

public class MainActivity extends AppCompatActivity {
private Toolbar toolbar;
private TabLayout tabLayout;
private ViewPager viewPager;
private Boolean exit = false;
private static final int REQUEST = 112;
private Context mContext;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    toolbar = (Toolbar) findViewById(R.id.toolbar);
    TextView mTitle = (TextView) toolbar.findViewById(R.id.toolbar_title);
    setSupportActionBar(toolbar);
    mTitle.setText(toolbar.getTitle());
    getSupportActionBar().setDisplayShowTitleEnabled(false);
    viewPager = (ViewPager) findViewById(R.id.viewpager);
    setupViewPager(viewPager);
    tabLayout = (TabLayout) findViewById(R.id.tabs);
    tabLayout.setupWithViewPager(viewPager);
    mContext = MainActivity.this;
    setupTabIcons();

}
@Override
protected void onResume()
{
    super.onResume();

}
private void setupTabIcons() {
    tabLayout.getTabAt(0).setIcon(getResources().getDrawable(R.drawable.settings));
    tabLayout.getTabAt(1).setIcon(getResources().getDrawable(R.drawable.download));
    tabLayout.getTabAt(2).setIcon(getResources().getDrawable(R.drawable.register));
    tabLayout.getTabAt(3).setIcon(getResources().getDrawable(R.drawable.profile));
    tabLayout.getTabAt(4).setIcon(getResources().getDrawable(R.drawable.favwhite));





}
private void setupViewPager(ViewPager viewPager) {
    ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
    adapter.addFragment(new SettingsFragment(), getResources().getString(R.string.settings_tab));
    adapter.addFragment(new DownloadFragment(), getResources().getString(R.string.download_tab));
    adapter.addFragment(new RegisterFragment(), getResources().getString(R.string.register_tab));
    adapter.addFragment(new ProfileFragment(), getResources().getString(R.string.profile_tab));
    adapter.addFragment(new ProfileFragment(), getResources().getString(R.string.favorites_tab));
    viewPager.setAdapter(adapter);
    viewPager.setOffscreenPageLimit(0);
}
class ViewPagerAdapter extends FragmentPagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public ViewPagerAdapter(FragmentManager manager) {
        super(manager);
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    public void addFragment(Fragment fragment, String title) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position);
    }
}
}

Update - To add more when it is run 4 times the data on screen is 4 times which is duplicate. Fragement Code -

public class RegisterFragment extends Fragment{

    public RegisterFragment() {
        // Required empty public constructor
    }

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

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment

        return inflater.inflate(R.layout.fragment_register, container, false);
    }
    @Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);
        if (isVisibleToUser) {
            getFragmentManager().beginTransaction().detach(this).attach(this).commit();
        }
    }

}

Answer 1

By default view pager load the fragment in the following order.

1. Currently selected position fragment. Visible
2. Cache for the (selected position - 1) fragment, if any. Not visible
3. Cache for the (selected position + 1) fragment, if any. Not visible

Reason for this is, to make smooth animation from one fragment to another without lagging, view pager caches the previous and the next fragment. To confirm this log the position in the getItem() method in the view pager adapter.

As a result of above. When launching activity your viewpager is loading position 0 and 1. ie loading 2 fragment. There is no fragment in -1 position.