Adding fragments dynamically on both sides of the ViewPager using the FragmentStatePagerAdapter

Question

In one of my applications, I need to add fragments on both sides of the ViewPager. First of all, I will get a constant of 5 channels, and my ViewPager will show the feed at index 2, i.e. The current displayed Fragment will contain the data present in index 2. Thus, my entire ViewPager will show the center of 5 channels at the beginning and what I have achieved by simply setting the current ViewPager to 2, like this

viewPager.setCurrentItem(2);

Now the user can scroll both sides, when he scrolls to the left of the central position, I will search for the next feed ie from the server and add the feed at the zero index of my ViewPager, like this

feedsList.add(0, modelClassObject); // feedsList will contain all feeds and has been used by adapter to show data in fragments.
adapter.notifyDataSetChanged();

and when I scroll right from the center position, I will add the feed last, just like

feedsList.add(modelClassObject);
adapter.notifyDataSetChanged();

, i.e feedsList, , , . , , , , , . , . .

private class HorizontalPagerAdapter extends FragmentStatePagerAdapter {

    public HorizontalPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int arg0) {
        return FeedUserProfileFragment.newInstance(feedsList.get(arg0),
                arg0);
    }

    @Override
    public int getCount() {
        return feedsList.size();
    }

}

@Override
    public int getItemPosition(Object object) {
        return POSITION_NONE;
    }

..: (

, , - , , , . ViewPager.

Answer 1

, :

• , .
• getItem(int arg0) , .
• , .

, :

:

private class HorizontalPagerAdapter extends FragmentStatePagerAdapter {

public List<Fragment> feedsList;

    public HorizontalPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int arg0) {
        return feedsList.get(i);
    }

    @Override
    public int getCount() {
        return feedsList.size();
    }

}

:

public static YourPageAdapter adapter_obj; // make sure it static object
adapter_obj =  new YourPageAdapter(getSupportFragmentManager());
adapter_obj.feedsList = new ArrayList<Fragment>();
// then add the list of fixed fragments to it(the 5 in the beginning)
adapter_obj.feedsList = fragments_list; // an ArrayList contains the 5 fragments

:

adapter_obj.feedsList.add(0, Fragment.instantiate(mContext, ViewPager_Container_Class.class.getName(), page));
adapter_obj.notifyDataSetChanged();

Answer 2

FragmentStatePagerAdapter , .

:

• .
• notifyDataSetChanged();
• .
• notifyDataSetChanged();

BTW, getItemPosition() :

public int getItemPosition(Object object)
{
    return feedsList.indexOf( object );
}

, :

newFrag = Fragment.instantiate(...);
feedsList.add( newFrag );
adapter_obj.notifyDataSetChanged();

feedsList.remove( feedsList.size() - 1 );
feedsList.add( 0, newFrag );
adapter_obj.notifyDataSetChanged();

, FragmentStatePagerAdapter .