java.lang.NullPointerException at android.support.v7.widget.RecyclerView.onMeasure

Question

I try to use RecyclerView with RecyclerView.Adapter but here is something wrong. I post my code below:

Layout:

Answer 1

For anyone trying to use a ViewPager for tabs, and inside their tabs have a RecyclerView which causes this crazy error, I suggest to postpone inflating by creating yet another Fragment for including only the RecylerView.

This xml file is one of my tabs which contain a frame layout instead a recycler .

shop_most_views_fragment.xml

its java class

public class MostViews extends Fragment {
private String title;
private int page;
View convertedView;
RecyclerView grids;

public static MostViews newInstance(int page, String title) {
    MostViews fragmentFirst = new MostViews();
    Bundle args = new Bundle();
    args.putInt("someInt", page);
    args.putString("someTitle", title);
    fragmentFirst.setArguments(args);
    return fragmentFirst;
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    page = getArguments().getInt("someInt", 0);
    title = getArguments().getString("someTitle");
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    convertedView = inflater.inflate(R.layout.shop_most_views_fragment, container, false);
    transitMasonaryLayoutFragmentIntoFramLayout();
    return convertedView;
}

private void transitMasonaryLayoutFragmentIntoFramLayout() {
    MasanoryLayout masanoryLayout = new MasanoryLayout();
    FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
    fragmentManager.beginTransaction()
            .add(R.id.most_view_item_frameLayout, masanoryLayout).commit();
}
}

so we have a frame layout to put our recylcer fragment into it.

shop_most_view_masanory_fragment.xml

its java class

public class MasanoryLayout extends Fragment {
View convertedView;
RecyclerView grids;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    convertedView = inflater.inflate(R.layout.shop_most_view_masanory_fragment, container, false);
    grids = (RecyclerView) convertedView.findViewById(R.id.mostViewsItem);
    setLayoutManagerOnRecyclerView();
    MasonryAdapter adapter = new MasonryAdapter(initializeData());
    grids.setAdapter(adapter);
    return convertedView;
}

private void setLayoutManagerOnRecyclerView() {
    grids.setLayoutManager(new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL));
}

private List initializeData() {
    List storeItems = new ArrayList<>();
    storeItems.add(new StoreItem("احسان", "احسان", R.drawable.detailed_index_store));
    storeItems.add(new StoreItem("احسان", "احسان", R.drawable.clothstore));
    storeItems.add(new StoreItem("احسان", "احسان", R.drawable.detailed_index_store));
    storeItems.add(new StoreItem("احسان", "احسان", R.drawable.clothstore));
    storeItems.add(new StoreItem("احسان", "احسان", R.drawable.detailed_index_store));
    storeItems.add(new StoreItem("احسان", "احسان", R.drawable.detailed_index_store));
    storeItems.add(new StoreItem("احسان", "احسان", R.drawable.clothstore));

    return storeItems;
}
}

as you see your FragmentPagerAdapter would call MostViews to be inflated and MostViews itself would call MasanoryLayout to be inflated. so we escaped FragmentPagerAdapter context ;)