Inflate ListView in a custom PagerAdapter makes setAdapter call ineffective

Question

I have tried to create a custom PagerAdapter since I want to show some pages, where each page contains a ListView, that should be initialized by the pager adapter constructor MyPagerAdapter, that receives the Activity where the ViewPager is used, and a list of Strings entries.

The problem is that setAdapter(myListAdapter) called on the ListView seems ineffective and listview appears empty.

Here the piece of code where I try to initialize the ListView:

 public class MyPagerAdapter extends PagerAdapter {
 ...
 public MyPagerAdapter( Activity activity, ArrayList<String> entries){
        mContext = activity.getBaseContext();
        inflater = LayoutInflater.from(mContext);
        ViewGroup viewGroup = (ViewGroup) activity.findViewById(R.id.pager);
        View v=inflater.inflate(R.layout.page1, viewGroup);
        ListView page_1_list = (ListView) v.findViewById(R.id.page_1_list);
        mylistAdapter = new ArrayAdapter(mContext, R.layout.spinner_item, entries);
        page_1_list.setAdapter(mylistAdapter);
 }
  ....
}

Could someone explain me why happens this and how could I fix the error?

The entries list isn't empty.
The ViewPager has several pages but here I'm showing only the list relative to the first page.
The issue has nothing to do with the xml since if I try to fill It directly from the activity works.
I'm able to google myself ViewPager tutorials. The question is related to a problem, and the answer should be related to the problem itself. So if your answer doesn't explain WHY listView cannot be filled with items with described approach It is off-topic and I will not accept It.

Why you doing this in constructor?. I think you should go with `Fragment` and [FragmentStatePagerAdapter](https://developer.android.com/reference/android/support/v4/app/FragmentStatePagerAdapter). — ADM, May 02 '18 at 13:37
This is not a way of doing such thing. Does the `ViewPager` contains endless items ? — ADM, May 02 '18 at 13:40
@ADM This is the Constructor of the PagerAdapter that I use in the Activity where I have the `ViewPager` (that is the `Activity` that is passed as argument in the constructor). — AndreaF, May 02 '18 at 13:40
Yeah i know this . But Does the ViewPager contains endless items ? Anyway yes/NO both cases i suggest to go with above solution . And to answer your question your code is not enough . So add complete code . — ADM, May 02 '18 at 13:42
@ADM read the question more carefully. The code is enough since the issue is related to the way I initialize the list indirectly in the adapter. — AndreaF, May 02 '18 at 13:47
what is the view `v` here? Also, the view pager contains fragments right? Why not initialize the lists in the fragment the proper way? — denvercoder9, May 02 '18 at 13:50
@rafid059 The v is where I inflate the layout of the single page. — AndreaF, May 02 '18 at 13:58

score 0 · Answer 1 · answered May 02 '18 at 14:00

You have to use FragmentStatePagerAdapter instead of directly use controllers in Pageradapter class. i.e:

public class CustomPagerAdapter extends FragmentStatePagerAdapter {

private ArrayList<String> entries;
private MyFragment myFragment;

public CustomPagerAdapter(FragmentManager fragmentManager, ArrayList<String> entries) {
    super(fragmentManager);
    this.entries = entries;
}

// Returns total number of pages
@Override
public int getCount() {
    return entries.size();
}

// Returns the fragment to display for that page
@Override
public Fragment getItem(int position) {
    myFragment = new MyFragment();
    final Bundle bundle = new Bundle();
   //pass your array list in bundle
    myFragment.setArguments(bundle);
    return myFragment;
}

// Returns the page title for the top indicator
@Override
public CharSequence getPageTitle(int position) {

    return title_of_viewpager;
}
}

Inflate ListView in a custom PagerAdapter makes setAdapter call ineffective

1 Answers1