Fragment inside ViewPager disappears on swiping - android-listview

Question

The Context
I have a HomeActivity that contains a NewsFragment. The NewsFragment contains a ListView to display news items in a list. I have a ViewPager that is added as a header-view to the ListView. This ViewPager appears as a header to the list and contains a DateFragment to display the date. The first time the user opens the HomeActivity, I want "TODAY" to be the date. When the user swipes the DateFragment to the left, I want the date text to show "TOMORROW". Swipe again and it should show the day after tomorrow. Similarly, when the user swipes in the other direction, I want to display "YESTERDAY", the day before yesterday etc. The ViewPager should support swiping infinitely (or a very large number) in both directions.
Here's how they are nested - http://tinypic.com/r/31623qw/8. (I don't have the reputation to post images yet, but this diagram is super useful for understanding this question).
The Problem
For simplicity, I'm displaying the index of the fragment as the date. When I first open the app, I see "Date: 0" being displayed as the date in the DateFragment. When I swipe the fragment to the left (to go to the next day), I can see the next fragment appear with "Date: 1" being displayed, but almost immediately, the fragment disappears. Once the fragment disappears, nothing reappears, and I just see an empty container. I can swipe to bring back the "Date: 0" Fragment, but I can't see any other Fragments. (I'm using the - Infinite View Pager by Antony T. - https://github.com/antonyt/InfiniteViewPager)
The Gory Details
I have a HomeActivity that contains a NewsFragment. The NewsFragment contains a ListView to display news items as a list. Here is the layout.xml for the NewsFragment:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ListView
android:id="#android:id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</LinearLayout>
I have a ViewPager that is dynamically added as a header to this list. So inside NewsFragment, I first initialize the ListView:
#Override
public View onCreateView(final LayoutInflater inflater, final ViewGroup container, final Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.home_news_fragment, container, false);
list = (ListView) view.findViewById(android.R.id.list);
emptyView = view.findViewById(android.R.id.empty);
list.setEmptyView(emptyView);
return view;
}
Next, in onActivityCreated(), I initialize and load the header for the ListView, and then load the news feed items:
#Override
public void onActivityCreated(final Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
loadHeader();
loadNewsFeed();
}
In the loadHeader() method, I then dynamically create a LinearLayout container to contain my ViewPager. I create a PagerAdapter for the ViewPager and I wrap it with an InfiniteViewPager to allow infinite swiping in both directions. I then create a ViewPager and I add it to the LinearLayout container. I then add the container as a Header View to the ListView:
private void loadHeader()
{
final LinearLayout headerContainer = new LinearLayout(getActivity());
headerContainer.setId(R.id.header_container_id);
headerContainer.setLayoutParams(new AbsListView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));
headerContainer.setOrientation(LinearLayout.VERTICAL);
// initialize the pager adapter for the view pager
PagerAdapter pagerAdapter = new HeaderPagerAdapter(getActivity().getSupportFragmentManager());
// Create a view pager. I use a custom implementation of a view pager I found from another Stackoverflow answer - WrapContentHeightViewPager - that allows ViewPager's layout.height to wrap content. The original ViewPager does not allow wrapping of content.
WrapContentHeightViewPager mViewPager = new WrapContentHeightViewPager(getActivity());
mViewPager.setId(R.id.view_pager_header);
mViewPager.setLayoutParams(new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.WRAP_CONTENT));
// wrap pager to provide infinite paging with wrap-around
PagerAdapter wrappedAdapter = new InfinitePagerAdapter(pagerAdapter);
mViewPager.setAdapter(wrappedAdapter);
// Add the view pager to the header container
headerContainer.addView(mViewPager);
// add the container as a header view to the list
list.addHeaderView(headerContainer);
}
In the loadNewsFeed() method, I do an async fetch of the news feed items and populate the list by adding the items into the footer view. I won't go into the implementation details for this - outside the scope of this question.
The NewsFragment contains my pager adapter, which contains the getItem method that initializes the Fragment to be displayed by the ViewPager:
private class HeaderPagerAdapter extends FragmentPagerAdapter
{
public HeaderPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int i) {
return DateFragment.newInstance(i);
}
#Override
public int getCount() {
return Integer.MAX_VALUE;
}
}
And here is the actual Fragment to be displayed inside the ViewPager:
public class DateFragment extends Fragment
{
private int index;
TextView date;
public static final DateFragment newInstance(int index) {
DateFragment fragment = new DateFragment();
final Bundle args = new Bundle(1);
args.putInt(Constants.Extras.PAGE_INDEX, index);
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
index = getArguments() != null ? getArguments().getInt(Constants.Extras.PAGE_INDEX) : 1;
}
#Override
public View onCreateView(final LayoutInflater inflater, final ViewGroup container, final Bundle savedInstanceState)
{
View v = (ViewGroup) inflater.inflate(R.layout.summary_fragment, container, false);
date = (TextView) v.findViewById(R.id.tvDate);
return v;
}
#Override
public void onActivityCreated(final Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
date.setText("Date: " + index);
}
}
For now I am simply using the index to be displayed as the date. I want to replace this with the actual date. Why does the fragment disappear on swipe?
Considerations:
Is there a refresh/redraw event that gets called?
Does it have to do with extending FragmentPagerAdapter vs. FragmentStatePagerAdapter
Override destroyItem() or instantiateItem()?
Set up a onPageScrolled listener on the ViewPager and then handle the page scroll events? I tried thehayro.blogspot.com/2012/12/enable-infinite-paging-with-android.html and that causes my fragments to disappear and then appear after a while.
Is it because I am adding the ViewPager as a header to the list view? The list view scrolls up and down and the view pager left and right. I've added this to my ViewPager implementation to tell the list view to stop intercepting our touch events:
#Override
public boolean onInterceptTouchEvent(MotionEvent ev)
{
// Tell our parent to stop intercepting our events!
boolean ret = super.onInterceptTouchEvent(ev);
if (ret)
{
getParent().requestDisallowInterceptTouchEvent(true);
}
return ret;
}
I'm sorry about the length of this post. I felt this much detail might be necessary. Thoughts?