Question

I have a ViewPager (extends FragmentPagerAdapter) which holds two Fragments. What I need is just refresh a ListView for each Fragment when I swipe among them. For this I have implemented ViewPager.OnPageChangeListener interface (namely onPageScrollStateChanged). In order to hold references to Fragments I use a HashTable. I store references to Fragments in HashTable in getItem() method:

  @Override
        public Fragment getItem(int num) {
            if (num == 0) {
                Fragment itemsListFragment = new ItemsListFragment();
                mPageReferenceMap.put(num, itemsListFragment);
                return itemsListFragment;
            } else {
                Fragment favsListFragment = new ItemsFavsListFragment();
                mPageReferenceMap.put(num, favsListFragment);
                return favsListFragment;
            }
        }

So when I swipe from one Fragment to another the onPageScrollStateChanged triggers where I use the HashTable to call required method in both Fragments (refresh):

 public void refreshList() {
        ((ItemsListFragment) mPageReferenceMap.get(0)).refresh();
        ((ItemsFavsListFragment) mPageReferenceMap.get(1)).refresh();
    }

Everything goes fine until orientation change event happens. After it the code in refresh() method, which is:

public void refresh() {
        mAdapter.changeCursor(mDbHelper.getAll());
        getListView().setItemChecked(-1, true); // The last row from a exception trace finishes here (my class).
    }

results in IllegalStateException:

java.lang.IllegalStateException: Content view not yet created
        at android.support.v4.app.ListFragment.ensureList(ListFragment.java:328)
        at android.support.v4.app.ListFragment.getListView(ListFragment.java:222)
        at ebeletskiy.gmail.com.passwords.ui.ItemsFavsListFragment.refresh(ItemsFavsListFragment.java:17)

Assuming the Content view is not created indeed I set the boolean variable in onActivityCreated() method to true and used if/else condition to call getListView() or not, which shown the activity and content view successfully created.

Then I was debugging to see when FragmentPagerAdapter invokes getItem() and it happens the method is not called after orientation change event. So looks like it ViewPager holds references to old Fragments. This is just my assumption.

So, is there any way to enforce the ViewPager to call getItem() again, so I can use proper references to current Fragments? May be some other solution? Thank you very much.

Answer 1

Then I was debugging to see when FragmentPagerAdapter invokes getItem() and it happens the method is not called after orientation change event. So looks like it ViewPager holds references to old Fragments.

The fragments should be automatically recreated, just like any fragment is on an configuration change. The exception would be if you used setRetainInstance(true), in which case they should be the same fragment objects as before.

So, is there any way to enforce the ViewPager to call getItem() again, so I can use proper references to current Fragments?

What is wrong with the fragments that are there?