FragmentPagerAdapter notifyDataSetChanged not working

Question

I got a FragmentPagerAdapter. It's getItem method can return a fragment according to data it has from the outside. After I update the data its suppose to display I call notifyDataSetChanged and yet nothing happened. I DID override the getItemPosition method to return POSITION_NONE:

public static class TabsAdapter extends FragmentPagerAdapter implements TabHost.OnTabChangeListener,         ViewPager.OnPageChangeListener {     private final Context mContext;     private final TabHost mTabHost;     private final ViewPager mViewPager;     private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();     private PagerTabsFragments fragmentDisplayInfo = null; // for now only a                                                             // single size                                                             // back                                                             // stack      static class PagerTabsFragments     {         public int tabPosition;         public Fragment fragmentToDisplay;         public Object fragmentInfo;          public PagerTabsFragments(int tab, Fragment frag, Object info)         {             tabPosition = tab;             fragmentToDisplay = frag;             fragmentInfo = info;         }     }      public void SetFragmentToDisplay(int tabPosition, Fragment frag, Object info)     {         fragmentDisplayInfo = new PagerTabsFragments(tabPosition, frag, info);         notifyDataSetChanged();     }      public void CancelFragmentToDisplay()     {         fragmentDisplayInfo = null;     } ... @Override     public Fragment getItem(final int position)     {         if ((fragmentDisplayInfo != null) && (fragmentDisplayInfo.tabPosition == position))         {             return fragmentDisplayInfo.fragmentToDisplay;         }         final TabInfo info = mTabs.get(position);         return Fragment.instantiate(mContext, info.clss.getName(), info.args);     }      @Override     public int getItemPosition(Object item)     {         if (fragmentDisplayInfo == null)         {             return super.getItemPosition(item);         }         return POSITION_NONE;     } ... 

And the update from outside is in a click event which sets the fragmentDisplayInfo var. I debuged and saw that the fragmentDisplayInfo is indeed initialized and the getItemPosition method does return POSITION_NONE, but the getItem method is not even called. Why is that?

EDIT:

If you hadn't done so as well, please notice that overiden part of the adapter:

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

Answer 1

What Nik Myers is saying is correct. However there is a piece missing. When notifyDataSetChanged is called, the method getItemPosition is called. You need to override this to get the fragments to reload.

 @Override     public int getItemPosition(Object object) {         // Causes adapter to reload all Fragments when         // notifyDataSetChanged is called         return POSITION_NONE;     }