Recycler View doesnt update the contains on notifyDataSetChanged

Question

I am using Recycler view to display a list of elements. Each row has a button on it when we click it status changes and its background color. I am calling notifyDataSetChanged() once the status is updated but recyclerView is not getting refreshed.

else if (allGoals.getStatus() == WorkoutCashConstants.GOALS_ACHIEVE) {
                        boolean networkStatus = checkNetworkStatus();
                        if (networkStatus) {
                            dateFormat = new SimpleDateFormat("yyyy-MM-dd");
                            if (DATE_ACCESS == null) {
                                currentTimeStamp = dateFormat.format(new Date());
                            } else {
                                currentTimeStamp = DATE_ACCESS;
                            }
                            progDialog = ProgressDialog.show(CompanyGoals_AllGoals_Fragment.this.getActivity(), "", "Goal Progress Recorded");
                            progDialog.setCancelable(true);
                            AchieveGoals achieveGoals = new AchieveGoals(Integer.parseInt(allGoals.getGoalID()), currentTimeStamp);
                            Call<AchieveGoals> achieveGoalsCall = apiModule.achieveGoal(achieveGoals);
                            achieveGoalsCall.enqueue(new Callback<AchieveGoals>() {
                                @Override
                                public void onResponse(Response<AchieveGoals> response, Retrofit retrofit) {
                                    progDialog.dismiss();
                                    if (response.isSuccess()) {
                                        progDialog.dismiss();
                                        goalsAchieved = response.body();
                                        if (goalsAchieved.getAppStatusCode() == WorkoutCashConstants.SUCCESS_API) {
                                            realm = Realm.getInstance(getContext());
                                            realm.beginTransaction();
                                            AllGoalsDB goalsDB = realm.where(AllGoalsDB.class)
                                                    .equalTo("goalID", allGoals.getGoalID()).findFirst();

                                            CompeletedDatesDB compeletedDatesDB = realm.createObject(CompeletedDatesDB.class);
                                            compeletedDatesDB.setCompletedDate(currentTimeStamp);
                                            goalsDB.getCompeletedDatesDBs().add(compeletedDatesDB);
                                            realm.commitTransaction();


                                            UserInfoDB userInfoDB = realm.where(UserInfoDB.class)
                                                    .equalTo(WorkoutCashConstants.
                                                            COLUMN_USER_ID, userId)
                                                    .findFirst();

                                            if (userInfoDB != null) {
                                                realm.beginTransaction();
                                                userInfoDB.setSweatPoints(goalsAchieved.getData().getSweatPoints());
                                                realm.commitTransaction();
                                            }




                                            realm.close();



                                            notifyDataSetChanged();

                                        }
                                    }

Answer 1

notifyDataSetChanged() checkes getItemCount() and if the item count in the list associated with the adapter is changed the notifyDataSetChanged() takes effect. In your case you might use a toggleSelection function inside your adapter. I'm attaching one of my example adapter so that, you can have an idea about how we can achieve this behaviour.

public class ToggleSelectionListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

        private Cursor mCursor;
        private SparseBooleanArray selectedItems;

        public ToggleSelectionListAdapter(Cursor cursor) {
            mCursor = cursor;
            selectedItems = new SparseBooleanArray();
        }

        public void toggleSelection(int pos) {
            if (selectedItems.get(pos, false)) {
                selectedItems.delete(pos);
            } else {
                selectedItems.put(pos, true);
            }
            notifyItemChanged(pos);
        }

        public int getSelectedItemCount() {
            return selectedItems.size();
        }

        public void clearSelections() {
            selectedItems.clear();
            notifyDataSetChanged();
        }

        public class ViewHolder extends RecyclerView.ViewHolder {

            public ViewHolder(final View itemView) {
                super(itemView);

                // Initialize your items of each row here
            }

            public void bindView(int pos) {
                try {
                    if (mCursor.isClosed())
                        return;

                    mCursor.moveToPosition(pos);

                    // Maintain a checked item list so that you can have a track if the item is clicked or not
                    if (checkedItems.contains(number) itemView.setBackgroundResource(R.drawable.background_selected);
                    else itemView.setBackgroundResource(R.drawable.background_normal);

                    itemView.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                                    if (checkedItems.contains(number)) {
                                        checkedItems.remove(number);
                                    } else {
                                        checkedItems.add(number);
                                    }

                                // Get the index of which item should toggle the background
                                int idx = mRecyclerView.getChildAdapterPosition(v);
                                toggleSelection(idx);
                            }
                        }
                    });
            }
        }


        @Override
        public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

            View v;

            v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_row, parent, false);

            ViewHolder vh = new ViewHolder(v);

            return vh;
        }

        @Override
        public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {

            if (holder instanceof ViewHolder) {
                ViewHolder vh = (ViewHolder) holder;

                vh.bindView(position);

            }
        }

        @Override
        public int getItemCount() {

            if (mCursor == null) {
                return 0;
            }

            int n = mCursor.getCount();
            return n;
        }

        @Override
        public int getItemViewType(int position) {
            return super.getItemViewType(position);
        }

        synchronized public void swapCursor(Cursor cursor) {
            mCursor = cursor;
            notifyDataSetChanged();
        }
    }