Fragments in viewpager not working properly

Question

I have 3 tabs in a viewpager and in all the 3 fragments i am calling the server using retrofit but when i launch the activity first 2 fragments are called and from both network is being called and when i go to position next tab nothing is displayed and position becomes 2.

The issue is when I come to the activity view pager is initialized and the pager adapter return two fragments which are at position 0 and 1 and inflate both so network is called from both of then but when I move tab to next position becomes 2...it should be 1.

Adapter Class:

public class PagerAdapter extends FragmentStatePagerAdapter {

private int mNumTabs;

    public PagerAdapter(FragmentManager fm, int numTabs) {
        super(fm);
        this.mNumTabs= numTabs;
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {

            case 0:
                Fragment1 tab0 = new Fragment1();
                return tab0;
            case 1:
                Fragment2 tab1 = new Fragment2();
                return tab1;
            case 2:
                Fragment3 tab2 = new Fragment3();
                return tab2;
            default:
                return null;
        }
    }

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

}

Activity Class :

public class UserProfileScreen extends AppCompatActivity {

    private ViewPager viewPager;
    private TabLayout tabLayout;
    private Context context;      
    private PagerAdapter PagerAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_user_profile_screen);
        context = this;
        initViews();
    tabLayout.addTab(tabLayout.newTab().setText("About"));
        tabLayout.addTab(tabLayout.newTab().setText("Session"));
        tabLayout.addTab(tabLayout.newTab().setText("Subjects"));
        pagerAdapter = new PagerAdapter(getSupportFragmentManager(), tabLayout.getTabCount());
        viewPager.setAdapter(profilePagerAdapter);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) {
                //Toast.makeText(context, "Unselected",Toast.LENGTH_LONG).show();
            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {
                //Toast.makeText(context, "Reselected",Toast.LENGTH_LONG).show();
            }
        });
    }

    private void initViews(){
        myToolbar = (Toolbar) findViewById(R.id.toolbar);
        tabLayout = (TabLayout) findViewById(R.id.profile_tab_layout);
        setSupportActionBar(myToolbar);
        viewPager = (ViewPager) findViewById(R.id.profile_viewPager);
    }

}

Fragment1 :

public class Fragment1 extends Fragment {

    private RecyclerView sessions_recycler_view;
    private SessionsAdapter sessionsAdapter;
    private SessionProfileFragmentPresenter presenter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        sessionsAdapter = new SessionsAdapter(getContext(),this);
    }

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

        sessions_recycler_view = (RecyclerView) view.findViewById(R.id.sessions_list);
        sessions_recycler_view.setAdapter(sessionsAdapter);

     //Server Call to get List<HashMap<String,Object>> data

      setDataToAdapter(data);

        return view;
    }


    private void setDataToAdapter(List<HashMap<String, Object>> sessions) {
        sessionsAdapter.setData(sessions);
    }

}

Fragment2 is also same as Fragment1.

Answer 1

I support Pramod Garg answer

Default OffscreenPageLimit of viewPager is 1 so the below code may useful for you. I just added the line viewpager.setOffscreenPageLimit(2).

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_user_profile_screen);
        context = this;
        initViews();
    tabLayout.addTab(tabLayout.newTab().setText("About"));
        tabLayout.addTab(tabLayout.newTab().setText("Session"));
        tabLayout.addTab(tabLayout.newTab().setText("Subjects"));
        pagerAdapter = new PagerAdapter(getSupportFragmentManager(), tabLayout.getTabCount());
        viewPager.setAdapter(profilePagerAdapter);
        viewpager.setOffscreenPageLimit(2)
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) {
                //Toast.makeText(context, "Unselected",Toast.LENGTH_LONG).show();
            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {
                //Toast.makeText(context, "Reselected",Toast.LENGTH_LONG).show();
            }
        });
    }