在选项卡式布局中加载片段后，选项卡消失

Question

我成功制作了一个标签式布局，但我有一个问题。标签显示但在加载第一个片段后消失。我不知道这是由于什么。这个代码试图找到错误。

片段的onCreateView，在i上显示cotaint。

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

// Initilization
viewPager = (ViewPager) v.findViewById(R.id.pager);
actionBar = getActivity().getActionBar();
mAdapter = new TabsPagerAdapter(getChildFragmentManager());

viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);

// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
        .setTabListener(this));
 }

 return v;

  }

主要类别：

public class ClubsPages extends android.support.v4.app.Fragment implements ActionBar.TabListener {


private OnFragmentInteractionListener mListener;


private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
// Tab titles
private String[] tabs = {"Clubs", "Pages"};

// TODO: Rename and change types and number of parameters
public static ClubsPages newInstance() {
    ClubsPages fragment = new ClubsPages();

    return fragment;
}
public ClubsPages() {
    // Required empty public constructor
}

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



}

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


    // Initilization
    viewPager = (ViewPager) v.findViewById(R.id.pager);
    actionBar = getActivity().getActionBar();

    mAdapter = new TabsPagerAdapter(getChildFragmentManager());

    viewPager.setAdapter(mAdapter);
    actionBar.setHomeButtonEnabled(false);
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

    // Adding Tabs
    for (String tab_name : tabs) {
        actionBar.addTab(actionBar.newTab().setText(tab_name)
                .setTabListener(this));
    }

    /**
     * on swiping the viewpager make respective tab selected
     * */
    /*viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

        @Override
        public void onPageSelected(int position) {
            // on changing the page
            // make respected tab selected
            actionBar.setSelectedNavigationItem(position);
        }

        @Override
        public void onPageScrolled(int arg0, float arg1, int arg2) {
        }

        @Override
        public void onPageScrollStateChanged(int arg0) {
        }
    });*/
    actionBar.show();

    return v;
}

// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
    if (mListener != null) {
        mListener.onFragmentInteraction(uri);
    }
}

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    try {
        mListener = (OnFragmentInteractionListener) activity;
    } catch (ClassCastException e) {
        throw new ClassCastException(activity.toString()
                + " must implement OnFragmentInteractionListener");
    }
}

@Override
public void onDetach() {
    super.onDetach();
    mListener = null;
}

@Override
public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {

}

@Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {

}

@Override
public void onTabReselected(ActionBar.Tab tab, FragmentTransaction ft) {

}

public interface OnFragmentInteractionListener {
    // TODO: Update argument type and name
    public void onFragmentInteraction(Uri uri);
}

}

我说在加载第一个片段后，标签会消失。所以有什么帮助吗？