NullPointerException on setMenuVisibility
<p>I'm following the next tutorial to insert a tab <a href="http://www.truiton.com/2015/06/android-tabs-example-fragments-viewpager/" rel="nofollow">http://www.truiton.com/2015/06/android-tabs-example-fragments-viewpager/</a>. My problem is that I'm trying to insert it in a fragment not in an activity, but I'm getting the next error.</p>

<pre><code>java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.app.Fragment.setMenuVisibility(boolean)' on a null object reference
   at android.support.v4.app.FragmentStatePagerAdapter.instantiateItem(FragmentStatePagerAdapter.java:116)
   at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:943)
   at android.support.v4.view.ViewPager.populate(ViewPager.java:1157)
   at android.support.v4.view.ViewPager.populate(ViewPager.java:1025)
   at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1545)
   at android.view.View.measure(View.java:18797)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
   at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1458)
   at android.widget.LinearLayout.measureVertical(LinearLayout.java:746)
   at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
   at android.view.View.measure(View.java:18797)
   at android.widget.ScrollView.measureChildWithMargins(ScrollView.java:1283)
   at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
   at android.widget.ScrollView.onMeasure(ScrollView.java:340)
   at android.view.View.measure(View.java:18797)
   at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
   at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
   at android.view.View.measure(View.java:18797)
   at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
   at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
   at android.view.View.measure(View.java:18797)
   at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
   at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
   at android.view.View.measure(View.java:18797)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
   at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:668)
   at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:735)
   at android.view.View.measure(View.java:18797)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
   at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
   at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
   at android.view.View.measure(View.java:18797)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
   at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:391)
   at android.view.View.measure(View.java:18797)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
   at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
   at android.view.View.measure(View.java:18797)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
   at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1458)
   at android.widget.LinearLayout.measureVertical(LinearLayout.java:746)
   at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
   at android.view.View.measure(View.java:18797)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
   at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
   at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2658)
   at android.view.View.measure(View.java:18797)
   at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2108)
   at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1224)
   at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1460)
   at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1115)
   at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6023)
   at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
   at android.view.Choreographer.doCallbacks(Choreographer.java:670)
   at android.view.Choreographer.doFrame(Choreographer.java:606)
   at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
at an...
</code></pre>

<p>The fragment that contains the tabhost and the viewpager is the next:</p>

<pre><code>public class AdministrarFragment extends Fragment {

    public static final String TAG = "AdministrarFragment";
    private FragmentIterationListener mCallback = null;
    public interface FragmentIterationListener{
        public void onFragmentIteration(Bundle parameters);
    }

    public static AdministrarFragment newInstance(Bundle arguments){
        AdministrarFragment f = new AdministrarFragment();
        if(arguments != null){
            f.setArguments(arguments);
        }
        return f;
    }

    public AdministrarFragment(){

    }

    //El fragment se ha adjuntado al Activity
    @Override
    public void onAttach(Context context) {
        super.onAttach(context);

        Activity activity = context instanceof Activity ? (Activity) context : null;
    }

    //El Fragment ha sido quitado de su Activity y ya no está disponible
    @Override
    public void onDetach() {
        super.onDetach();
    }

    //La vista ha sido creada y cualquier configuración guardada está cargada
    @Override
    public void onViewStateRestored(Bundle savedInstanceState) {
        super.onViewStateRestored(savedInstanceState);
    }

    //El Activity que contiene el Fragment ha terminado su creación
    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
    }

    //El fragment se ha adjuntado al Activity
    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

        mCallback = (FragmentIterationListener) activity;

    }

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

        TabLayout tabLayout = (TabLayout) view.findViewById(R.id.tab_layout);
        tabLayout.addTab(tabLayout.newTab().setText(getString(R.string.tiempo)));
        tabLayout.addTab(tabLayout.newTab().setText(getString(R.string.gastos)));
        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

        final ViewPager viewPager = (ViewPager) view.findViewById(R.id.pager);
        final AdministrarPageAdapter adapter = new AdministrarPageAdapter(getActivity().getSupportFragmentManager(), tabLayout.getTabCount());
        viewPager.setAdapter(adapter);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
        tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }

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

            }

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

            }
        });

        return view;
    }
}
</code></pre>

<p>And this is my pageadapter:</p>

<pre><code>public class AdministrarPageAdapter extends FragmentStatePagerAdapter {
    int mNumOfTabs;

    public AdministrarPageAdapter(FragmentManager fm, int NumOfTabs) {
        super(fm);
        this.mNumOfTabs = NumOfTabs;
    }

    @Override
    public Fragment getItem(int position) {

        switch (position) {
            case 0:
                AdministrarTiemposFragment tab_tiempos = new AdministrarTiemposFragment();
                return tab_tiempos;
            /*case 1:
                TabFragment2 tab2 = new TabFragment2();
                return tab2;
            case 2:
                TabFragment3 tab3 = new TabFragment3();
                return tab3;*/
            default:
                return null;
        }
    }

    @Override
    public int getCount() {
        return mNumOfTabs;
    }
}
</code></pre>