如何获得片段在活动中的位置？

Question

I am new to android. I have a sliding tab layout and a viewpager with a fragment. I have setup a basic link between these to switch tabs for a count of 5(ie 5 tabs) The problem is that, in each of these tabs, I want to populate a listview using simplecursoradapter, for which I need the position of each fragment so that I could populate it accordingly. I have got the position in the fragment adapter class, but I am unable to pass it to the main activity. Also, How can I access DBadapter inside my fragment class to populate listview from the database? or is there some other way to do this? Below is my code. Any help is greatly appreciated. Thanks in advance.

public class myFragment extends Fragment{
    private ListView mainList;
    public static myFragment getInstance(int position){
        myFragment MyFragment = new myFragment();
        Bundle args = new Bundle();
        args.putInt("position", position);
        MyFragment.setArguments(args);

        return MyFragment;
    }
    @Override
    public View onCreateView(LayoutInflater inflater,
            @Nullable ViewGroup container,
            @Nullable Bundle savedInstanceState) {

            View layout = inflater.inflate(R.layout.fragment_main_list,container, false);
            mainList = (ListView)layout.findViewById(R.id.mainListView);
            Bundle bundle = getArguments();

            if(bundle!=null){
                if(bundle.getInt("position")==0){
                mainList.setBackgroundColor(getResources().getColor(R.color.primary500));
            }
            else if(bundle.getInt("position")==1){
                mainList.setBackgroundColor(getResources().getColor(R.color.primary100));
            }
            else if(bundle.getInt("position")==2){
                mainList.setBackgroundColor(getResources().getColor(R.color.primary700));
            }
            else if(bundle.getInt("position")==3){
                mainList.setBackgroundColor(getResources().getColor(R.color.accent));
            }
            else if(bundle.getInt("position")==4){
                mainList.setBackgroundColor(getResources().getColor(R.color.black));
            }

            }
            return layout;
    }   

}

The Main Activity is as follows:

public class MainActivity extends ActionBarActivity {
private Toolbar toolbar;
private ViewPager mPage;
private SlidingTabLayout mTabs;
DBadapter myDb;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    openDB();

    toolbar = (Toolbar)findViewById(R.id.app_bar);
    mPage = (ViewPager)findViewById(R.id.pager);
    mTabs = (SlidingTabLayout)findViewById(R.id.tabs);
    mFab = (FloatingActionButton)findViewById(R.id.fab);

    setSupportActionBar(toolbar);
    mPage.setAdapter(new myPagerAdapter(getSupportFragmentManager()));
    mTabs.setViewPager(mPage);
}
public class myPagerAdapter extends FragmentPagerAdapter{
        String[] tabs;
        public myPagerAdapter(FragmentManager fm) {
            super(fm);
            tabs = getResources().getStringArray(R.array.tabs);
        }

        @Override
        public Fragment getItem(int position) {
            myFragment MyFragment = myFragment.getInstance(position);
            return MyFragment;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return tabs[position];
        }

        @Override
        public int getCount() {
            return 5;
        }

    } 

Answer 1

Use this method :

mPage.setOnPageChangeListener(new SimpleOnPageChangeListener() {

            @Override
            public void onPageSelected(int pos) {
              // pos is the position of fragment that app showing
        });

UPDATE
in your view pager adapter :

public Fragment getItem(int position) {
    return new myFragment(position);
 } 

And in your fragment class :

public class myFragment extends Fragment{

private int pos
public void myFragment(int position){
   this.pos = position;
}
// other code of your class