How do i refresh fragment in ViewPager

Question

I have a MainActivity and a HomeTabs with three tabs(A B C) all of them are Fragment. I set a onRefresh on tab C. When I trigger onRefresh that its view is gone. Why is that? I couldn't solve it.

Any help would be appreciated. Thanks in advance.

Here's my HomeTabs:

public class HomeTabs extends Fragment {
    private Context context;
    private TabLayout tabLayout;

    private int[] imageResId = {R.drawable.input_icon_color,
            R.drawable.note_icon_color,
            R.drawable.analytics_icon_color};

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

    public static HomeTabs newInstance() {
        return new HomeTabs();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_home_tabs, container, false);

        tabLayout = (TabLayout) view.findViewById(R.id.tabLayout);
        tabLayout.addTab(tabLayout.newTab().setText(getResources().getString(R.string.tab1)));
        tabLayout.addTab(tabLayout.newTab().setText(getResources().getString(R.string.tab2)));
        tabLayout.addTab(tabLayout.newTab().setText(getResources().getString(R.string.tab3)));
        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

        final ViewPager viewPager = (ViewPager) view.findViewById(R.id.viewPagerDataReport);

        ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter(getFragmentManager(), tabLayout.getTabCount());
        viewPager.setAdapter(viewPagerAdapter);

        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));

        tabLayout.getTabAt(0).setIcon(R.drawable.input_icon);
        tabLayout.getTabAt(1).setIcon(imageResId[1]);
        tabLayout.getTabAt(2).setIcon(imageResId[2]);

        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());/

                int id = tab.getPosition();
                if (id == 0) {
                    tabLayout.getTabAt(0).setIcon(R.drawable.input_icon);
                    tabLayout.getTabAt(1).setIcon(imageResId[1]);
                    tabLayout.getTabAt(2).setIcon(imageResId[2]);
                }

                if (id == 1) {
                    tabLayout.getTabAt(0).setIcon(imageResId[0]);
                    tabLayout.getTabAt(1).setIcon(R.drawable.note_icon);
                    tabLayout.getTabAt(2).setIcon(imageResId[2]);
                }

                if (id == 2) {
                    tabLayout.getTabAt(0).setIcon(imageResId[0]);
                    tabLayout.getTabAt(1).setIcon(imageResId[1]);
                    tabLayout.getTabAt(2).setIcon(R.drawable.analytics_icon);
                }
            }

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

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

        // My tab C position is 2 , when i refresh that i want to show tab C
        if (getActivity().getIntent().hasExtra("refresh")){
            tabLayout.getTabAt(2).select();
        }

        return view;
    }
}

Here is my tab C Fragment about refresh:

@Override
public void onRefresh() {
    refreshLayout.setRefreshing(false);

    MainActivity mainActivity = (MainActivity) getActivity();
    mainActivity.refreshFragment();
}

And the MainActivity:

public class MainActivity extends AppCompatActivity {

    private FrameLayout frameLayout;
    private Toolbar toolBar;

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

        toolBar = (Toolbar) findViewById(R.id.toolBar);
        setSupportActionBar(toolBar);
        getSupportActionBar().setTitle("");
        toolBar.setTitle(R.string.myAppName);
        toolBar.setNavigationIcon(R.drawable.medical_history32);
        toolBar.setTitleTextColor(Color.WHITE);

        frameLayout = (FrameLayout) findViewById(R.id.frameLayout);

        if (savedInstanceState == null) {
            switchFragment(HomeTabs.newInstance());
        }


    }

    public void switchFragment(Fragment fragment) {
        FragmentManager manager = getSupportFragmentManager();
        FragmentTransaction transaction = manager.beginTransaction();
        transaction.replace(R.id.frameLayout, fragment);
        transaction.addToBackStack(null);
        transaction.commit();
    }



    public void setTitle(String title) {
        getSupportActionBar().setTitle(title);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            new DialogHandler(this).quickDialog(
                    getResources().getString(R.string.quick),
                    getResources().getString(R.string.confirm),
                    getResources().getString(R.string.cancel),
                    new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {

                            finish();
                        }
                    }, new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {

                        }
                    });
        }
        return super.onKeyDown(keyCode, event);
    }


    public void refreshFragment() {
        //switchFragment(HomeTabs.newInstance());
        Intent intent = new Intent(this,MainActivity.class);
        intent.putExtra("refresh",true);
        startActivity(intent);
    }

}

Here's my tab C:

public class MyLineChart extends Fragment implements SwipeRefreshLayout.OnRefreshListener{
    private View view;
@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.fragment_my_line_chart, container, false);

        //................set my data

        return view;
    }

    @Override
    public void onRefresh() {
        refreshLayout.setRefreshing(false);

    }

Answer 1

There are many ways to do it. If you are using ViewPager the best solution is found here.

You must implement (override) getItemPosition method in your page adapter to return (no position changed)

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

Then to update from anywhere, you just notify the adapter of a change

mPagerAdapter.notifyDataSetChanged();