Android TabLayout PagerAdapter not showing first tab fragment

Question

First tab does not show the fragment.

I am using the following method to create new tabs.

public static void addNewTab(String TimelineName, String id) {
 TabLayout.Tab tab = tabs.newTab();
 tab.setText(TimelineName)
 tabs.addTab(tab);
 adapter.addTab(TimelineName);
}

adapter.add(Timeline) is a method in the following class:

public class TabsPagerAdapter extends PagerAdapter {

private final ArrayList<CharSequence> myTabList = new ArrayList<>();
int TabPosition = 0;
public static List<Bean_TimelineData> timelineData;
public static TimeLine_Adapter timeLineAdapter;
public static RecyclerView timelineRecyclerView;

// CREATE NEW TAB
public void addTab(String title) {
myTabList.add(title);
notifyDataSetChanged();
}

public void removeTab() {
if (!myTabList.isEmpty()) {
myTabList.remove(myTabList.size() - 1);
notifyDataSetChanged();
 }
}

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


@Override
public Object instantiateItem(ViewGroup container, int position) {
LinearLayout linearLayout = new LinearLayout(container.getContext());
timelineRecyclerView = new RecyclerView(container.getContext());

SwipeRefreshLayout swipeContainer;
timelineData = new ArrayList<Bean_TimelineData>();
timeLineAdapter = new TimeLine_Adapter(container.getContext(), timelineData, TabId);
timelineRecyclerView.setLayoutManager(new LinearLayoutManager(container.getContext()));

timelineRecyclerView.setAdapter(timeLineAdapter);
linearLayout.setOrientation(LinearLayout.VERTICAL);
linearLayout.setBackgroundColor(Color.parseColor("#f2f2f2"));

container.addView(linearLayout, ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT);

LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.WRAP_CONTENT
);

params.setMargins(0, 20, 0, 0);

timelineRecyclerView.setLayoutParams(params);

linearLayout.addView(timelineRecyclerView);

return linearLayout;
}

@Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}

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

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
}

But the the result i get is this:

Rest all tabs are working correctly:

If i swipe tab from 1 to 3 and then go back to 1 the fragment appears back correctly.

I have checked a few post regarding this such as:This SO post

Nothing Worked.

EDIT

I want to dynamically add tabs. On the first tab the tab pageradapter is not being called.That is why the first tab is showing empty, rest all works correctly.

Answer 1

use FragmentPagerAdapter .

For adding Fragment to FragmentPagerAdapter, Follow it -

public class WeatherFragment extends Fragment {

    private Toolbar toolbar;
    private ViewPager viewPager;
    private ViewPagerAdapter viewPagerAdapter;
    private TabLayout tabLayout;

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

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

        //setup viewpager
        viewPager = (ViewPager) weatherFragment.findViewById(R.id.viewpager);
        tabLayout = (TabLayout) weatherFragment.findViewById(R.id.tabs);

        viewPagerAdapter = new ViewPagerAdapter(getChildFragmentManager());

        viewPager.setAdapter(viewPagerAdapter);
        tabLayout.setupWithViewPager(viewPager);

        return weatherFragment;
    }

And

public class ViewPagerAdapter extends FragmentPagerAdapter {
    public ViewPagerAdapter(FragmentManager fragmentManager) {
        super(fragmentManager);
    }

    @Override
    public Fragment getItem(int position) {
        if(position == 0) return new TodayTabFragment();
        if(position == 1) return new TomorrowTabFragment();
        if(position == 2) return new TenDaysTabFragment();

        throw new IllegalStateException("Unexpected position " + position);
    }

    @Override
    public int getCount() {
        return 3;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        if(position == 0) return "Tab 1";
        if(position == 1) return "Tab 2";
        if(position == 2) return "Tab 3";
      
        throw new IllegalStateException("Unexpected position " + position);
    }
}

To get a reference to a Fragment created by a ViewPager, use the following findFragmentByTag scheme:

Fragment fragment = supportFragmentManager.findFragmentByTag("android:switcher:" + viewPager.getId() + ":" + fragmentPosition)

Layout file for Fragment.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <android.support.design.widget.TabLayout
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:tabMode="fixed"
        android:background="@color/colorlightBlue"
        app:tabGravity="fill"
        app:tabTextColor="@color/colorWhite"
        app:tabSelectedTextColor="@color/colorWhite"
        app:tabIndicatorColor="@color/colorWhite"
        app:tabIndicatorHeight="2dp"/>


    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scrollbarAlwaysDrawVerticalTrack="true"
        android:scrollbarAlwaysDrawHorizontalTrack="true"/>

</LinearLayout>