How to update RecyclerView Adapter Data

Question

Trying to figure out what is the issue with updating RecyclerView s Adapter    After I get a new List of products  I tried to    Update the ArrayList from the fragment where recyclerView is created  set new data to adapter  then call adapter notifyDataSetChanged     it did not work  Create a new adapter  as others did  and it worked for them  but no change for me  recyclerView setAdapter new RecyclerViewAdapter newArrayList    Create a method in Adapter which updates the data as follows   public void updateData ArrayList lt ViewModel gt  viewModels       items clear       items addAll viewModels      notifyDataSetChanged        Then I call this method whenever I want to update the data list  it did not work   To check if I can modify the recyclerView in any way  and I tried to remove at least an item    public void removeItem int position        items remove position       notifyItemRemoved position       Everything remained as it was    Here is my Adapter   public class RecyclerViewAdapter extends RecyclerView Adapter lt RecyclerViewAdapter ViewHolder gt  implements View OnClickListener        private ArrayList lt ViewModel gt  items      private OnItemClickListener onItemClickListener       public RecyclerViewAdapter ArrayList lt ViewModel gt  items            this items   items              public void setOnItemClickListener OnItemClickListener onItemClickListener            this onItemClickListener   onItemClickListener              Override     public ViewHolder onCreateViewHolder ViewGroup parent  int viewType            View v   LayoutInflater from parent getContext    inflate R layout item recycler  parent  false           v setOnClickListener this           return new ViewHolder v              public void updateData ArrayList lt ViewModel gt  viewModels            items clear            items addAll viewModels           notifyDataSetChanged              public void addItem int position  ViewModel viewModel            items add position  viewModel           notifyItemInserted position              public void removeItem int position            items remove position           notifyItemRemoved position                 Override     public void onBindViewHolder ViewHolder holder  int position            ViewModel item   items get position           holder title setText item getTitle             Picasso with holder image getContext    load item getImage    into holder image           holder price setText item getPrice             holder credit setText item getCredit             holder description setText item getDescription              holder itemView setTag item               Override     public int getItemCount             return items size                Override     public void onClick final View v               Give some time to the ripple to finish the effect         if  onItemClickListener    null                new Handler   postDelayed new Runnable                      Override                 public void run                         onItemClickListener onItemClick v   ViewModel  v getTag                                      0                        protected static class ViewHolder extends RecyclerView ViewHolder           public ImageView image          public TextView price  credit  title  description           public ViewHolder View itemView                super itemView               image    ImageView  itemView findViewById R id image               price    TextView  itemView findViewById R id price               credit    TextView  itemView findViewById R id credit               title    TextView  itemView findViewById R id title               description    TextView  itemView findViewById R id description                        public interface OnItemClickListener            void onItemClick View view  ViewModel viewModel              And I initiate RecyclerView as follows   recyclerView    RecyclerView  view findViewById R id recycler   recyclerView setLayoutManager new GridLayoutManager getActivity    5    adapter   new RecyclerViewAdapter items   adapter setOnItemClickListener this   recyclerView setAdapter adapter     So  how do I actually update adapter data in order to display newly received items     Update  the issue was that the layout where gridView was looked as follows    lt  xml version  1 0  encoding  utf-8   gt   lt LinearLayout     xmlns android  http   schemas android com apk res android      android orientation  vertical      android layout width  match parent      android tag  catalog fragment      android layout height  match parent  gt        lt FrameLayout         android orientation  vertical          android layout width  match parent          android layout height  match parent  gt            lt android support v7 widget RecyclerView             android id    id recycler              android layout width  match parent              android layout height  match parent              android clipToPadding  false   gt            lt ImageButton             android id    id fab              android layout gravity  top end              style   style FabStyle   gt        lt  FrameLayout gt   lt  LinearLayout gt    Then I just removed LinearLayout and made FrameLayout as parent layout

User · Answer

This is what worked for me   recyclerView setAdapter new RecyclerViewAdapter newList    recyclerView invalidate      After creating a new adapter that contains the updated list  in my case it was a database converted into an ArrayList  and setting that as adapter  I tried recyclerView invalidate   and it worked

User · Answer

I strongly recommend you to use  DiffUtil ItemCallback  1  to handle the change in RecyclerView Adapter   fun setData data  List lt T gt             val calculateDiff   DiffUtil calculateDiff DiffUtilCallback items  data           items clear           items    data         calculateDiff dispatchUpdatesTo this         under the hood it handles most of the things with AdapterListUpdateCallback         ListUpdateCallback that dispatches update events to the given adapter         see DiffUtil DiffResult dispatchUpdatesTo RecyclerView Adapter      public final class AdapterListUpdateCallback implements ListUpdateCallback        NonNull     private final RecyclerView Adapter mAdapter                  Creates an AdapterListUpdateCallback that will dispatch update events to the given adapter                 param adapter The Adapter to send updates to              public AdapterListUpdateCallback  NonNull RecyclerView Adapter adapter            mAdapter   adapter                   inheritDoc          Override     public void onInserted int position  int count            mAdapter notifyItemRangeInserted position  count                    inheritDoc          Override     public void onRemoved int position  int count            mAdapter notifyItemRangeRemoved position  count                    inheritDoc          Override     public void onMoved int fromPosition  int toPosition            mAdapter notifyItemMoved fromPosition  toPosition                    inheritDoc          Override     public void onChanged int position  int count  Object payload            mAdapter notifyItemRangeChanged position  count  payload

User · Answer

Another option is  to use diffutil   It will compare the original list against the new list and use the new list as the update if there is a change   Basically  we can use DiffUtil to compare the old data vs new data and let it call notifyItemRangeRemoved  and notifyItemRangeChanged and notifyItemRangeInserted on your behalf    A quick example of using diffUtil instead of notifyDataSetChanged   DiffResult diffResult   DiffUtil                  calculateDiff new MyDiffUtilCB getItems    items       any clear up on memory here and then diffResult dispatchUpdatesTo this      and then  if necessary items clear   items addAll newItems    I do the calculateDiff work off the main thread in case it s a big list

User · Answer

This is a general answer for future visitors  The various ways to update the adapter data are explained  The process includes two main steps every time   Update the data set Notify the adapter of the change   Insert single item Add  quot Pig quot  at index 2   String item    quot Pig quot   int insertIndex   2  data add insertIndex  item   adapter notifyItemInserted insertIndex     Insert multiple items Insert three more animals at index 2   ArrayList lt String gt  items   new ArrayList lt  gt     items add  quot Pig quot    items add  quot Chicken quot    items add  quot Dog quot    int insertIndex   2  data addAll insertIndex  items   adapter notifyItemRangeInserted insertIndex  items size       Remove a single item Remove  quot Pig quot  from the list   int removeIndex   2  data remove removeIndex   adapter notifyItemRemoved removeIndex     Remove multiple items Remove  quot Camel quot  and  quot Sheep quot  from the list   int startIndex   2     inclusive int endIndex   4       exclusive int count   endIndex - startIndex     2 items will be removed data subList startIndex  endIndex  clear    adapter notifyItemRangeRemoved startIndex  count     Remove all items Clear the whole list   data clear    adapter notifyDataSetChanged      Replace old list with the new list Clear the old list then add a new one      clear old list data clear        add new list ArrayList lt String gt  newList   new ArrayList lt  gt     newList add  quot Lion quot    newList add  quot Wolf quot    newList add  quot Bear quot    data addAll newList       notify adapter adapter notifyDataSetChanged     The adapter has a reference to data  so it is important that I didn t set data to a new object  Instead  I cleared the old items from data and then added the new ones   Update single item Change the  quot Sheep quot  item so that it says  quot I like sheep  quot   String newValue    quot I like sheep  quot   int updateIndex   3  data set updateIndex  newValue   adapter notifyItemChanged updateIndex     Move single item Move  quot Sheep quot  from position 3 to position 1   int fromPosition   3  int toPosition   1      update data array String item   data get fromPosition   data remove fromPosition   data add toPosition  item       notify adapter adapter notifyItemMoved fromPosition  toPosition     Code Here is the project code for your reference  The RecyclerView Adapter code can be found at this answer  MainActivity java public class MainActivity extends AppCompatActivity implements MyRecyclerViewAdapter ItemClickListener        List lt String gt  data      MyRecyclerViewAdapter adapter        Override     protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout activity main               data to populate the RecyclerView with         data   new ArrayList lt  gt             data add  quot Horse quot            data add  quot Cow quot            data add  quot Camel quot            data add  quot Sheep quot            data add  quot Goat quot                set up the RecyclerView         RecyclerView recyclerView   findViewById R id rvAnimals           LinearLayoutManager layoutManager   new LinearLayoutManager this           recyclerView setLayoutManager layoutManager           DividerItemDecoration dividerItemDecoration   new DividerItemDecoration recyclerView getContext                    layoutManager getOrientation             recyclerView addItemDecoration dividerItemDecoration           adapter   new MyRecyclerViewAdapter this  data           adapter setClickListener this           recyclerView setAdapter adapter               Override     public void onItemClick View view  int position            Toast makeText this   quot You clicked  quot    adapter getItem position     quot  on row number  quot    position  Toast LENGTH SHORT  show               public void onButtonClick View view            insertSingleItem               private void insertSingleItem             String item    quot Pig quot           int insertIndex   2          data add insertIndex  item           adapter notifyItemInserted insertIndex              private void insertMultipleItems             ArrayList lt String gt  items   new ArrayList lt  gt             items add  quot Pig quot            items add  quot Chicken quot            items add  quot Dog quot            int insertIndex   2          data addAll insertIndex  items           adapter notifyItemRangeInserted insertIndex  items size                private void removeSingleItem             int removeIndex   2          data remove removeIndex           adapter notifyItemRemoved removeIndex              private void removeMultipleItems             int startIndex   2     inclusive         int endIndex   4       exclusive         int count   endIndex - startIndex     2 items will be removed         data subList startIndex  endIndex  clear            adapter notifyItemRangeRemoved startIndex  count              private void removeAllItems             data clear            adapter notifyDataSetChanged               private void replaceOldListWithNewList                clear old list         data clear                add new list         ArrayList lt String gt  newList   new ArrayList lt  gt             newList add  quot Lion quot            newList add  quot Wolf quot            newList add  quot Bear quot            data addAll newList               notify adapter         adapter notifyDataSetChanged               private void updateSingleItem             String newValue    quot I like sheep  quot           int updateIndex   3          data set updateIndex  newValue           adapter notifyItemChanged updateIndex              private void moveSingleItem             int fromPosition   3          int toPosition   1              update data array         String item   data get fromPosition           data remove fromPosition           data add toPosition  item               notify adapter         adapter notifyItemMoved fromPosition  toPosition             Notes  If you use notifyDataSetChanged    then no animation will be performed  This can also be an expensive operation  so it is not recommended to use notifyDataSetChanged   if you are only updating a single item or a range of items  Check out DiffUtil if you are making large or complex changes to a list    Further study  CodePath  Using the RecyclerView Smart way to update RecyclerView using DiffUtil

User · Answer

If nothing mentioned in the above comments is working for you  It might mean the problem lies somewhere else   One place I found the solution was in the way I was setting the list to the adapter  In my activity the list was a instance variable and I was changing it directly when any data changed  Due to it being a reference variable there was something weird going on  So I changed the reference variable to a local one and used another variable to update data and then pass to addAll   function mentioned in above answers

User · Answer

you have 2 options to do this  refresh UI from the adapter   mAdapter notifyDataSetChanged      or refresh it from recyclerView itself   recyclerView invalidate

User · Answer

The best and the coolest way to add new data to the present data is   ArrayList lt String gt  newItems   new ArrayList lt String gt      newItems   getList     int oldListItemscount   alcontainerDetails size     alcontainerDetails addAll newItems               recyclerview getAdapter   notifyItemChanged oldListItemscount 1  al containerDetails

User · Answer

These methods are efficient and good to start using a basic RecyclerView   private List lt YourItem gt  items   public void setItems List lt YourItem gt  newItems        clearItems        addItems newItems      public void addItem YourItem item  int position        if  position  gt  items size    return       items add item       notifyItemInserted position      public void addMoreItems List lt YourItem gt  newItems        int position   items size     1      newItems addAll newItems       notifyItemChanged position  newItems      public void addItems List lt YourItem gt  newItems        items addAll newItems       notifyDataSetChanged       public void clearItems         items clear        notifyDataSetChanged       public void addLoader         items add null       notifyItemInserted items size   - 1      public void removeLoader         items remove items size   - 1       notifyItemRemoved items size        public void removeItem int position        if  position  gt   items size    return       items remove position       notifyItemRemoved position      public void swapItems int positionA  int positionB        if  positionA  gt  items size    return      if  positionB  gt  items size    return       YourItem firstItem   items get positionA        videoList set positionA  items get positionB        videoList set positionB  firstItem        notifyDataSetChanged        You can implement them inside of an Adapter Class or in your Fragment or Activity but in that case you have to instantiate the Adapter to call the notification methods  In my case I usually implement it in the Adapter

User · Answer

I ve solved the same problem in a different way  I don t have data I waiting for it from the background thread so start with an emty list           mAdapter   new ModelAdapter getContext   new ArrayList lt Model gt            then when i get data          mAdapter update response getModelList           and update is in my adapter          public void update ArrayList lt Model gt  modelList               adapterModelList clear                 for  Product model  modelList                    adapterModelList add model                             mAdapter notifyDataSetChanged                That s it

User · Answer

Update Data of listview  gridview and recyclerview  mAdapter notifyDataSetChanged      or   mAdapter notifyItemRangeChanged 0  itemList size

User · Answer

i got the answer after a long time     SELECTEDROW add dt                   notifyItemInserted position                   SELECTEDROW remove position                   notifyItemRemoved position

User · Answer

I m working with RecyclerView and both the remove and the update work well   1  REMOVE  There are 4 steps to remove an item from a RecyclerView  list remove position   recycler removeViewAt position   mAdapter notifyItemRemoved position                    mAdapter notifyItemRangeChanged position  list size       These line of codes work for me   2  UPDATE THE DATA  The only things I had to do is  mAdapter notifyDataSetChanged      You had to do all of this in the Actvity Fragment code not in the RecyclerView Adapter code

User · Answer

I found out that a really simple way to reload the RecyclerView is to just call  recyclerView removeAllViews      This will first remove all content of the RecyclerView and then add it again with the updated values

[android] How to update RecyclerView Adapter Data?

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