ViewPager Inside Fragment that is part of tabs in FragmentActivity

Question

I'm trying to build something that I'm not sure if it's possible. I have Fragment tabs (using FragmentActivity, TabHost and TabWidget as my fragment tabs container) and in each of the fragments I want to have, as top bar, another fragments. You can look at this as - bottom bar constructed of types of items, and top bar that would be filters. I want to snap between the filters in regular gesture.

The behavior of my app is the following: I can see the main activity in which the first fragment sits, i can see the top/bottom bar, but i can't see the view(fragment) of the first top bar category. When I'm trying to snap to the other category nothing happens.

This is the code for the fragment:

Public class Tab1Fragment extends Fragment {

private ViewPager _mViewPager;
private ViewPagerAdapter _adapter;
private View child;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    if (container == null) {
        return null;
    }

    child = inflater.inflate(R.layout.tab_frag1_layout, container);

    _mViewPager = (ViewPager) child.findViewById(R.id.viewPager);
    _adapter = new ViewPagerAdapter(GlobalContext.getAppContext(),getFragmentManager());
    _mViewPager.setCurrentItem(0);

    new setAdapterTask().execute();

    return (LinearLayout) inflater.inflate(R.layout.tab_frag1_layout,
            container, false);
}

private class setAdapterTask extends AsyncTask<Void, Void, Void> {
    protected Void doInBackground(Void... params) {
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        _mViewPager.setAdapter(_adapter);
        _mViewPager.setCurrentItem(0);
    }
}

public void onActivityCreated(Bundle bdl) {
    super.onActivityCreated(bdl);

    _mViewPager.setOnPageChangeListener(new OnPageChangeListener() {

        @Override
        public void onPageScrollStateChanged(int position) {
        }

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

        @Override
        public void onPageSelected(int position) {
            // TODO Auto-generated method stub
            switch (position) {
            case 0:
                child.findViewById(R.id.first_tab).setVisibility(
                        View.VISIBLE);
                child.findViewById(R.id.second_tab)
                        .setVisibility(View.GONE);
                break;

            case 1:
                child.findViewById(R.id.first_tab).setVisibility(View.GONE);
                child.findViewById(R.id.second_tab).setVisibility(
                        View.VISIBLE);
                break;
            }
        }

    });

}

}

This is the xml for the outer Fragment:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@color/white"
android:orientation="vertical" >  

<TableLayout
    style="@style/layout_f_w"
    android:stretchColumns="*" >
    <TableRow
        android:id="@+id/tableRow1"
        android:background="#dddddd"
        style="@style/layout_wrap">

          <!-- First Tab -->
            <LinearLayout
            style="@style/layout_f_w"
            android:id="@+id/first_text"
            android:orientation="vertical" >

                  <TextView
                    android:id="@+id/textView1"
                    style="@style/text_title"
                    android:text="Tab1" />
           </LinearLayout>

        <!-- Second Tab -->
            <LinearLayout
            style="@style/layout_f_w"
            android:id="@+id/second_text"
            android:orientation="vertical" >

                <TextView
                    android:id="@+id/textView1"
                    style="@style/text_title"
                    android:text="Tab2" />

           </LinearLayout>

    </TableRow>
 </TableLayout>
 <!-- Include Tab Indicator  -->
 <include layout="@layout/indicator" android:layout_width="fill_parent"
  android:layout_height="wrap_content"  />

<android.support.v4.view.ViewPager
    android:layout_width="fill_parent" android:layout_height="fill_parent"
    android:id="@+id/viewPager" />
</LinearLayout>

This is an example for my first category fragment(the fragment category that inside the first fragment):

public class LayoutOne extends Fragment {


public static Fragment newInstance(Context context) {
    LayoutOne f = new LayoutOne();  

    return f;
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
    ViewGroup root = (ViewGroup) inflater.inflate(R.layout.layout_one, null);       
    return root;
}

}

Please help me :(

This is my Fragment Adapter:

public class ViewPagerAdapter extends FragmentStatePagerAdapter {
private Context _context;

public ViewPagerAdapter(Context context, FragmentManager fm) {
    super(fm);  
    _context=context;

    }
@Override
public Fragment getItem(int position) {
    Fragment f = new Fragment();
    switch(position){
    case 0:
        f=LayoutOne.newInstance(_context);  
        break;
    case 1:
        f=LayoutTwo.newInstance(_context);  
        break;
    }
    return f;
}
@Override
public int getCount() {
    return 2;
}
@Override
public boolean isViewFromObject(View arg0, Object arg1) {
    // TODO Auto-generated method stub
    return false;
}

}

Answer 1

Finally we have nested fragments in 4.2 and compatibility http://developer.android.com/about/versions/jelly-bean.html

Answer 2

and in each of the fragments I want to have, as top bar, another fragments

Having fragments inside of fragments is not supported, sorry.

Update: Nested fragments are supported as of Android 4.2 (and Android Support Library rev 11) : http://developer.android.com/about/versions/android-4.2.html#NestedFragments