public class NewsFragment extends Fragment implements  OnPageChangeListener {
    private View view=null;
    private RadioGroup rgChannel=null;
    private ViewPager viewPager;
    private HorizontalScrollView hvChannel=null;
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        
 
if(view==null){
            view=inflater.inflate(R.layout.news_fragment_layout, null);
            rgChannel=(RadioGroup)view.findViewById(R.id.rgChannel);
            viewPager=(ViewPager)view.findViewById(R.id.vpNewsList);
            hvChannel=(HorizontalScrollView)view.findViewById(R.id.hvChannel);
            rgChannel.setOnCheckedChangeListener(
                    
 
new RadioGroup.OnCheckedChangeListener() {
                @Override
                public void onCheckedChanged(RadioGroup group, 
                        int checkedId) {
                    viewPager.setCurrentItem(checkedId);        
                }
            });            
            initTab(inflater);
            initViewPager();
        }
        ViewGroup parent
 
=(ViewGroup)view.getParent();
        if(parent!=null){
            parent.removeView(view);
        }
        return view;
    }
private List<Fragment> newsChannelList=new ArrayList<Fragment>();
private NewsPageFragmentAdapter adapter;
         private void initViewPager(){
        List<Channel> channelList=ChannelDb.getSelectedChannel();
        for(int i=0;i<channelList.size();i++){
            NewsChannelFragment  fragment=new NewsChannelFragment();
            Bundle bundle=new Bundle();
            bundle.putString("cname", channelList.get(i).getName());
            fragment.setArguments(bundle);
            newsChannelList.add(fragment);
        }
        adapter=new NewsPageFragmentAdapter(super.getActivity().getSupportFragmentManager(), newsChannelList);
        viewPager.setAdapter(adapter);
        viewPager.setOffscreenPageLimit(2);
        viewPager.setCurrentItem(0);
        viewPager.setOnPageChangeListener(this);
    }
    private void initTab(LayoutInflater inflater){
        List<Channel> channelList=ChannelDb.getSelectedChannel();
        for(int i=0;i<channelList.size();i++){
            RadioButton rb=(RadioButton)inflater.
                    inflate(R.layout.tab_rb, null);
            rb.setId(i);
            rb.setText(channelList.get(i).getName());
            RadioGroup.LayoutParams params=new 
        RadioGroup.LayoutParams(RadioGroup.LayoutParams.WRAP_CONTENT,
                            RadioGroup.LayoutParams.WRAP_CONTENT);
            rgChannel.addView(rb,params);
        }
        rgChannel.check(0);
    }
    @Override
    public void onPageScrollStateChanged(int arg0) {
    }
    @Override
    public void onPageScrolled(int arg0, float arg1, int arg2) {
    }
    @Override
    public void onPageSelected(int idx) {
        setTab(idx);
    }
    private void setTab(int idx){
        RadioButton rb=(RadioButton)rgChannel.getChildAt(idx);
        rb.setChecked(true);
        int left=rb.getLeft();
        int width=rb.getMeasuredWidth();
        DisplayMetrics metrics=new DisplayMetrics();
        super.getActivity().getWindowManager().getDefaultDisplay().getMetrics(metrics);
        int screenWidth=metrics.widthPixels;
        int len=left+width/2-screenWidth/2;
        hvChannel.smoothScrollTo(len, 0);
    }

}