Tabs of TabLayout not showing

Question

I have a main activity, which hosts a fragment, which in turn hosts a TabLayout (with a ViewPager). The tab bar is shown, baut the tabs themselves are not shown.

Here is my code in the main activity for displaying the host fragment:

        Fragment fragment = new BMITabsFragment();

        FragmentManager fragmentManager = getSupportFragmentManager();
        fragmentManager.beginTransaction().replace(R.id.content_frame, fragment).addToBackStack(Constants.BMI_TABS_FRAGMENT).commit();

Here is my the Fragment which hosts the TabLayout, which is BMITabsFragment (s.a.):

public class BMITabsFragment extends Fragment {
...
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (getArguments() != null) {
        mParam1 = getArguments().getString(ARG_PARAM1);
        mParam2 = getArguments().getString(ARG_PARAM2);
    }

}

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    // Get the ViewPager and set it's PagerAdapter so that it can display items
    ViewPager viewPager = (ViewPager) view.findViewById(R.id.viewpager);
    viewPager.setAdapter(new BMIFragmentPagerAdapter(getActivity().getSupportFragmentManager(),
            getActivity()));

    // Give the TabLayout the ViewPager
    TabLayout tabLayout = (TabLayout) view.findViewById(R.id.sliding_tabs);
    tabLayout.setupWithViewPager(viewPager);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_bmitabs, container, false);
    return view;
}
...
}

This is my FragmentPagerAdapter:

public class BMIFragmentPagerAdapter extends FragmentPagerAdapter {

final int PAGE_COUNT = 2;
private FragmentManager fragmentManager;
private Context context;

public BMIFragmentPagerAdapter(FragmentManager fm, Context context) {
    super(fm);
    this.context = context;
    this.fragmentManager = fm;

}

public BMIFragmentPagerAdapter(FragmentManager fm) {
    super(fm);
    fragmentManager = fm;

}

@Override
public CharSequence getPageTitle(int position) {
    String[] pageTitles = context.getResources().getStringArray(R.array.page_titles_array);
    return pageTitles[position];
}

@Override
public Fragment getItem(int position) {
    SharedPreferences prefs = context.getSharedPreferences(Constants.SHARED_PREFS_FILE, 0);
    long patientId = prefs.getLong(Constants.SELECTED_PATIENT_ID, 1);
    Fragment fragment = null;
    switch (position){
        case 0:
            return BMITabelleFragment.newInstance(patientId);

        case 1:
            return BMIChartFragment.newInstance(patientId);

        default:
            return BMITabelleFragment.newInstance(patientId);
    }
}

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

And this is the fragment_bmitabs.xml:

<?xml version="1.0" encoding="utf-8"?>

<android.support.design.widget.TabLayout
    android:id="@+id/sliding_tabs"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:tabMode="scrollable" />

<android.support.v4.view.ViewPager
    android:id="@+id/viewpager"
    android:layout_width="match_parent"
    android:layout_height="0px"
    android:layout_weight="1"
    android:background="@android:color/white" />

</LinearLayout>

My code is based on the Google Android Guide at https://github.com/codepath/android_guides/wiki/Google-Play-Style-Tabs-using-TabLayout

What I am missing here?

Note: I am using AppCompatActivity and the support libraries v4 & v7 and the com:android:support:design library

Answer 1

None of the other answers worked for me, I tried all of them

However, this one did: TabLayout not showing tabs after adding navigation bar

According to that answer, you have to enclose your TabLayout in a AppBarLayout. Why? Who knows. But at least it works.

Example Code (taken from that post):

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="200dp"
    android:id="@+id/appBarLayout2">


    <android.support.design.widget.TabLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tabLayout2"
        app:tabMode="fixed"
        app:tabGravity="fill"

        ></android.support.design.widget.TabLayout>

</android.support.design.widget.AppBarLayout>

<android.support.v4.view.ViewPager
    android:layout_width="match_parent"
    android:layout_height="300dp"
    android:layout_alignParentStart="true"
    android:layout_alignParentBottom="true"
    android:id="@+id/viewPager2"
    android:layout_below="@+id/appBarLayout2">

</android.support.v4.view.ViewPager>

Answer 2

Set tab icons after setupWithViewPager()

private void setTabs {
   tabLayout.setupWithViewPager(viewPager);
   setupTabIcons();
} 

private void setupTabIcons() {
   tabLayout.getTabAt(0).setIcon(tabIcons[0]);
   tabLayout.getTabAt(1).setIcon(tabIcons[1]);
   tabLayout.getTabAt(2).setIcon(tabIcons[2]);
}