How to re create the fragment in viewpager

Question

I have a viewpager with 5 tabs , each tab is fragment showing different data to user , each fragment have recycleview inside itself , and i need to re insert updated data into the recyclerview when user change the tab, and I need to update the view

Every time I swipe to a tab, a new instance of the fragment in that tab needs to load so that data will be updated.

I have tried:

1- I used FragmentStatePagerAdapter (nothing happens)

2- I Override getItemPosition method to return PagerAdapter.POSITION_NONE; (nothing happens)

3- setOffscreenPageLimit(0) (Nothing happens)

4- refresh function inside each fragment to be called onTabSelected (gives nullPointerException)

How can i recreate fragment from scratch each time user change the tab i really need to know.

I have been struggling with this problem for a week with no progress. I appreciate any help, be it a hint, a comment, a suggestion.

Let me know what code should I post, Thanks.

Edit: my codes:

MainActivity:

public class Sefaresh_activity3 extends AppCompatActivity implements Serializable, Sefaresh3_interface {
    Context context;
    Toolbar mtoolbar;
    private List<Food> food_list = new ArrayList<>();

    MyPagerAdapter adapter;
    Custom_TabLayout mTabLayout;
    ViewPager mpager;
@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sefaresh_activity3);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
            getWindow().getDecorView().setLayoutDirection(View.LAYOUT_DIRECTION_LTR);
        }

        context = this;
        sqlHelper = new SqlHelper(this);
setupTabs();

private void setupTabs() {
        mtoolbar = (Toolbar) findViewById(R.id.app_bar);
        setSupportActionBar(mtoolbar);

        SpannableString s = new SpannableString(getTitle());
        s.setSpan(new TypefaceSpan(this, "IRAN Sans Bold.ttf"), 0, s.length(),
                Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
        setTitle(s);

        try {
            getSupportActionBar().setHomeButtonEnabled(true);
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        } catch (Exception e) {
            L.m("something is wrong in toolbar section");
        }

        adapter = new MyPagerAdapter(getSupportFragmentManager());

        mTabLayout = (Custom_TabLayout) findViewById(R.id.tab_layout);
        mpager = (ViewPager) findViewById(R.id.viewpager);
        mpager.setAdapter(adapter);

        mTabLayout.setTabsFromPagerAdapter(adapter);
        mTabLayout.setupWithViewPager(mpager);

        mpager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(mTabLayout));
        mTabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                L.m("tab selected" + tab.getPosition());
                mpager.setCurrentItem(tab.getPosition());

//                    Sefaresh3_fragment all_fragment = (Sefaresh3_fragment) adapter.getFragment_all();
//                    sefaresh3_fragment.onRefresh();

//                    Sefaresh3_fragment sefaresh3_fragment = (Sefaresh3_fragment) adapter.fragment_all;
//                    adapter.notifyDataSetChanged();

            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        });

    }

class MyPagerAdapter extends FragmentStatePagerAdapter {
       // public ArrayList<Fragment> fragmentArrayList = new ArrayList<>();
        Fragment fragment_all;
        Fragment fragment_pizza;
        Fragment fragment_sandwich;
        Fragment fragment_salad;
        Fragment fragment_coca;

        public Fragment getFragment_coca() {
            return fragment_coca;
        }

        public Fragment getFragment_all() {
            return fragment_all;
        }

        public Fragment getFragment_pizza() {
            return fragment_pizza;
        }

        public Fragment getFragment_sandwich() {
            return fragment_sandwich;
        }

        public Fragment getFragment_salad() {
            return fragment_salad;
        }

        String[] tabs = {
                "products",
                "new products",
                "featured",
                "star",
                "star2"
        };

        @Override
        public int getItemPosition(Object object) {
            return PagerAdapter.POSITION_NONE;
        }

        public MyPagerAdapter(FragmentManager fm) {
            super(fm);
            tabs = getResources().getStringArray(R.array.sefaresh3_tabs);
        }

        @Override
        public int getItemPosition(Object object) {
            return POSITION_NONE;
        }

        @Override
        public Fragment getItem(int num) {
            Fragment fragment = null;
            orders = new Orders();
            orders.setOrders(all_orders);
            switch (num) {
                case 0:
//                    fragment_all = Sefaresh3_fragment.newInstance("all", "");
//                    return new Sefaresh3_fragment().newInstance("all","");
                    return Sefaresh3_fragment.newInstance("all","");
                case 1:
                    fragment_pizza = Sefaresh3_fragment.newInstance("pizza", "");
                    return fragment_pizza;
                case 2:
                    fragment_sandwich = Sefaresh3_fragment.newInstance("sandwich", "");
                    return fragment_sandwich;
                case 3:
                    fragment_salad = Sefaresh3_fragment.newInstance("salad", "");
                    return fragment_salad;
                case 4:
                    fragment_coca = Sefaresh3_fragment.newInstance("coca", "");
                    return fragment_coca;
                default:
                    return fragment;
            }
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return tabs[position];
        }

        @Override
        public int getCount() {
            return 5;
        }

    }

Answer 1

thanks for everybody suggestions , after one week struggling with this problem I found the solution.

I tried several methods but finally I just found the solution.

I used Broadcast receiver to tell the fragment update the list , and every time I need to update the fragments to update the data list , I call the broadcaster. its awesome and it works well

If anyone had the same problem I will be happy to help him :) thanks.