Question

this question might be very noobish but I’m just not able to find a right solution.

So here is my problem:

I want do display the data (a java.util.List with my TaskObjects) in multiple ExpandableLists (lets say 5) each in a own Fragment so that the user is able to swipe between the different Lists.
At the moment I have a MainFragmentActivity that contains the java.util.List, the PageViewer and a ‘extended’ FragmentPagerAdapter (like TabsAdapter) that contains the Tabs AllTaskFragment and OverDueTaskFragment. These two Fragments have each a own ExpandableList and ExpandableListAdapter (writen by me).

Now when the user clicks on a child in any ExpandableLists how do i need to notify the other Fragments ExpandableListAdapter to update? I tried to call the MainFragmentActivity and from there call all Fragments but then the fragments ExpandableListAdapters were ‘null’, but why?

update:

I guess I solved the issue, atm Is working with:

If something changes in any ExpandableListAdapter, I call updateTabs() in

MainFragmentActivity

    public void updateTabs() {
        for(int i = 0 ; i < tabsAdapter.getCount() ; i++) {
            UpdateableFragment updateableFragment = (UpdateableFragment) getSupportFragmentManager().findFragmentByTag(makeFragmentName(mViewPager.getId(),i));
            updateableFragment.updateFragment();
        }
    }

    private String makeFragmentName(int viewId, int index){
         return "android:switcher:" + viewId + ":" + index;
    }

which simply calls in each fragment the method

public void updateFragment() {
         adapter.notifyDataSetChanged();
}

Is this a good approach? Or will this maybe rise some issues?

Answer 1

The key thing for such applications is to keep track of the ArrayAdapters. If you call ArrayAdapter.notifyDataSetChanged(), it will tell its view to update.