Display a RecyclerView in Fragment

Question

I m trying out the new RecyclerView in Android Lollipop and I m stuck   I m trying to receive a list  with an icon and a TextView to the right of the icon  inside a Fragment   I found this great tutorial on how to set up a RecyclerView  I have followed every point and only changed the item layout xml to fit my needs   The project builds without any errors but when it launches on my device I m getting this error      java lang RuntimeException  Unable to start activity ComponentInfo com fredrikaldgard materialcolors com fredrikaldgard materialcolors MainActivity   java lang NullPointerException  Attempt to invoke virtual method  void android support v7 widget RecyclerView setLayoutManager android support v7 widget RecyclerView LayoutManager   on a null object reference   I ve tried to google the problem but I m quite an amateur with Android development   Here s my MainActivity    Override protected void onCreate Bundle savedInstanceState        super onCreate savedInstanceState       setContentView R layout activity main           1  get a reference to recyclerView     RecyclerView recyclerView    RecyclerView  findViewById R id list           2  set layoutManger     recyclerView setLayoutManager new LinearLayoutManager this            this is data fro recycler view     ItemData itemsData       new ItemData  Indigo  R drawable circle               new ItemData  Red  R drawable color ic launcher               new ItemData  Blue  R drawable indigo               new ItemData  Green  R drawable circle               new ItemData  Amber  R drawable color ic launcher               new ItemData  Deep Orange  R drawable indigo             3  create an adapter     MyAdapter mAdapter   new MyAdapter itemsData          4  set adapter     recyclerView setAdapter mAdapter          5  set item animator to DefaultAnimator     recyclerView setItemAnimator new DefaultItemAnimator       And my MyAdapter   public class MyAdapter extends RecyclerView Adapter lt MyAdapter ViewHolder gt    private ItemData   itemsData   public MyAdapter ItemData   itemsData        this itemsData   itemsData        Create new views  invoked by the layout manager   Override public MyAdapter ViewHolder onCreateViewHolder ViewGroup parent                                                 int viewType           create a new view     View itemLayoutView   LayoutInflater from parent getContext                 inflate R layout item layout  null           create ViewHolder      ViewHolder viewHolder   new ViewHolder itemLayoutView       return viewHolder        Replace the contents of a view  invoked by the layout manager   Override public void onBindViewHolder ViewHolder viewHolder  int position            - get data from your itemsData at this position        - replace the contents of the view with that itemsData      viewHolder txtViewTitle setText itemsData position  getTitle         viewHolder imgViewIcon setImageResource itemsData position  getImageUrl             inner class to hold a reference to each item of RecyclerView public static class ViewHolder extends RecyclerView ViewHolder        public TextView txtViewTitle      public ImageView imgViewIcon       public ViewHolder View itemLayoutView            super itemLayoutView           txtViewTitle    TextView  itemLayoutView findViewById R id item title           imgViewIcon    ImageView  itemLayoutView findViewById R id item icon                Return the size of your itemsData  invoked by the layout manager   Override public int getItemCount         return itemsData length        Edit  Here s the Fragment  public class ColorsFragment extends Fragment        public ColorsFragment           Override     public View onCreateView LayoutInflater inflater  ViewGroup container                           Bundle savedInstanceState             View rootView   inflater inflate R layout fragment colors  container  false            return rootView            What has possibly gone wrong

User · Answer

Make sure that you have the correct layout  and that the RecyclerView id is inside the layout  Otherwise  you will be getting this error  I had the same problem  then I noticed the layout was wrong       public class ColorsFragment extends Fragment             public ColorsFragment                 Override          public View onCreateView LayoutInflater inflater  ViewGroup container               Bundle savedInstanceState        gt  make sure you are getting the correct layout here  R layout                  View rootView   inflater inflate R layout fragment colors  container  false

User · Answer

This was asked some time ago now  but based on the answer that  nacho zona3 provided  and previous experience with fragments  the issue is that the views have not been created by the time you are trying to find them with the findViewById   method in onCreate   to fix this  move the following code      1  get a reference to recyclerView RecyclerView recyclerView    RecyclerView  findViewById R id list       2  set layoutManger recyclerView setLayoutManager new LinearLayoutManager this        this is data fro recycler view ItemData itemsData       new ItemData  Indigo  R drawable circle           new ItemData  Red  R drawable color ic launcher           new ItemData  Blue  R drawable indigo           new ItemData  Green  R drawable circle           new ItemData  Amber  R drawable color ic launcher           new ItemData  Deep Orange  R drawable indigo         3  create an adapter MyAdapter mAdapter   new MyAdapter itemsData      4  set adapter recyclerView setAdapter mAdapter      5  set item animator to DefaultAnimator recyclerView setItemAnimator new DefaultItemAnimator        to your fragment s onCreateView   call  A small amount of refactoring is required because all variables and methods called from this method have to be static  The final code should look like    public class ColorsFragment extends Fragment         public ColorsFragment             Override      public View onCreateView LayoutInflater inflater  ViewGroup container           Bundle savedInstanceState              View rootView   inflater inflate R layout fragment colors  container  false               1  get a reference to recyclerView          RecyclerView recyclerView    RecyclerView  rootView findViewById R id list                2  set layoutManger          recyclerView setLayoutManager new LinearLayoutManager getActivity                   this is data fro recycler view          ItemData itemsData                    new ItemData  Indigo   R drawable circle                    new ItemData  Red   R drawable color ic launcher                    new ItemData  Blue   R drawable indigo                    new ItemData  Green   R drawable circle                    new ItemData  Amber   R drawable color ic launcher                    new ItemData  Deep Orange   R drawable indigo                            3  create an adapter          MyAdapter mAdapter   new MyAdapter itemsData               4  set adapter          recyclerView setAdapter mAdapter               5  set item animator to DefaultAnimator          recyclerView setItemAnimator new DefaultItemAnimator               return rootView              So the main thing here is that anywhere you call findViewById   you will need to use rootView findViewById

User · Answer

You should retrieve RecyclerView in a Fragment after inflating core View using that View  Perhaps it can t find your recycler because it s not part of Activity   Override public View onCreateView LayoutInflater inflater  ViewGroup container                               Bundle savedInstanceState        final View view   inflater inflate R layout fragment artist tracks  container  false       final FragmentActivity c   getActivity        final RecyclerView recyclerView    RecyclerView  view findViewById R id recyclerView       LinearLayoutManager layoutManager   new LinearLayoutManager c       recyclerView setLayoutManager layoutManager        new Thread new Runnable              Override         public void run                 final RecyclerAdapter adapter   new RecyclerAdapter c               c runOnUiThread new Runnable                      Override                 public void run                         recyclerView setAdapter adapter                                                      start         return view

User · Answer

I faced same problem  And got the solution when I use this code to call context  I use Grid Layout  If you use another one you can change     recyclerView setLayoutManager new GridLayoutManager getActivity   1     if you have adapter to set  So you can follow this  Just call the getContext   adapter   new Adapter getContext    myModelList    If you have Toast to show  use same thing above    Toast makeText getContext     quot Error in  quot  e  Toast LENGTH SHORT  show     Hope this will work  HappyCoding

[java] Display a RecyclerView in Fragment

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