ViewPager blank after Navigation from DrawerLayout list

Question

Here's the structure of my App

HomeActivity replaces the contentArea with either TransScreen or FlowScreen. Both are Fragments (support v4).

HomeActivity (drawerlayout containing contentArea frameLayout + menu ListView)
- TransScreen (fragment with viewPager + actionbar tabs)
  - InListFragment (ListFragment)
  - OutListFragment (ListFragment)
- FlowScreen (fragment)

When the app starts up, TransScreen is the default screen - I see the lists - all good here. Switch from Drawer menu to FlowScreen, that's fine too. Now when I switch back to TransScreen, I see the tabs but blank content in the ViewPager (not the 'empty' message or the listView).

Tried debugging, on the first render of the TransScreen, I see the getItem method of the ViewPager's adapter (derived from FragmentStatePagerAdapter) is called (call stack starts from ViewPager.populate()) But when I switch to another screen and back again, TransScreen::onCreateView() is called but the subsequent getItem calls are not being triggered.

Here's what TransScreen onCreateView looks like:

pseudo code onCreateView()

_tabsPager = new ViewPager(activity); // from getActivity()
_tabsPager.setId(R.id.transactionsTabCarousel);

_tabsPager.setAdapter(_tabsAdapter);
            _tabsPager.setOnPageChangeListener(syncSelectedActionBarTabOnPageSelectListener());

ActionBar actionBar = activity.getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);


TabListener tabListener = getSyncPagerOnTabSelectListener();
actionBar.addTab(createActionTab(actionBar, tab1Text, tabListener));
actionBar.addTab(createActionTab(actionBar, tab2Text, tabListener));

Log.d(TAG, "onCreate end!");

return _tabsPager;

_tabsAdapter is created in onCreate() and does a lookup in an internal Fragment array during getItem(position). However getItem only seems to be called the first time and not after I switch to this Screen via the drawerLayout - pullout menu.

public TransactionTabsAdapter(FragmentManager fm) {
        super(fm);
        try {
            _fragments = new Fragment[2];
            _fragments[0] = new InListFragment();
            _fragments[1] = new OutListFragment();
        } catch (Exception e) {
            Log.e(TAG, "TabsAdapter ctor", e);
        }

    }

No exceptions in LogCat.

Tried passing in getChildFragmentManager to the tabsAdapter inside first level fragment TransScreen. No dice.

Another update:

So to eliminate the possibility that I messed up in TransScreen. I downloaded the code for the following android sample http://developer.android.com/samples/SlidingTabsColors/index.html

I then substituted TransScreen with SlidingTabsColorFragment()

HomeActivity:onCreate

...
        _screens = new Fragment[]{ 
new SlidingTabsColorsFragment(), //new TransactionsScreen()
new CashFlowScreen() };
        setScreen(0);
    }

    private void setScreen(int position) {
        try {
            FragmentManager fm = getSupportFragmentManager();
            fm.beginTransaction()
                .replace(R.id.contentArea, _screens[position])
                .commit();
            _drawerMenu.setItemChecked(position, true);
            _drawerLayout.closeDrawer(_drawerMenu);
        } catch (Exception e) {
            Log.e(TAG, "setScreen via Drawer Menu", e);
        }
    }

Same problem reproducible - and with a stack trace

: threadid=1: thread exiting with uncaught exception (group=0x41be52a0)
: FATAL EXCEPTION: main
: java.lang.IllegalStateException: No activity
:   at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1091)
:   at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1086)
:   at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1884)
:   at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1514)
:   at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:947)
:   at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
:   at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
:   at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
:   at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:440)
:   at android.os.Handler.handleCallback(Handler.java:615)
:   at android.os.Handler.dispatchMessage(Handler.java:92)
:   at android.os.Looper.loop(Looper.java:137)
:   at android.app.ActivityThread.main(ActivityThread.java:4921)
:   at java.lang.reflect.Method.invokeNative(Native Method)
:   at java.lang.reflect.Method.invoke(Method.java:511)
:   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
:   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
:   at dalvik.system.NativeStart.main(Native Method)

here is the solution -> http://stackoverflow.com/questions/16600156/fragment-in-viewpager-not-restored-after-popbackstack?rq=1 — Abhishek Chauhan, Jan 10 '15 at 14:32

Gishu · Answer 1 · 2014-10-06T09:08:09.010

So the answer seems to be : Don't use ViewPager with nested fragments - it doesn't work.

So I looked at an app that had what I wanted.. basically a simple NavDrawer which allows you to jump to different screens, one or more of which could contain a viewpager. So I looked at the Google IO App source.

Lessons learned:.

Use activities for different screens - I was using fragments. When you click on a nav drawer option, spawn the new activity. Suppress default animations + use fade in/out to obtain a less jarring transition.
So now for the screen, we have a ViewPager with single level fragments. (as opposed to a fragment containing a viewpager with tab child fragments)
It seems SlidingTabLayout is preferred over ActionBar tabs (which is what i was using)

The issue isn't solved. With these changes, it's a good enough workaround

ViewPager blank after Navigation from DrawerLayout list

1 Answers1