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Recycler Adapter callback nullpointer

i have recycler adapter like this
public class ShopUsersAdapter extends RecyclerView.Adapter<ShopUsersAdapter.MyViewHolder> implements View.OnClickListener {
private List<ShopUsersRecyclerModel> user_list;
private Context context;
private AdminCheckLocActivity activity;
private AdapterCallback mAdapterCallback;
public class MyViewHolder extends RecyclerView.ViewHolder {
public TextView user;
public TextView type;
private ImageButton btn_loc;
public MyViewHolder(View view) {
super(view);
user = (TextView) view.findViewById(R.id.txt_text);
type =(TextView)view.findViewById(R.id.txt_count);
btn_loc=(ImageButton)view.findViewById(R.id.btn_loc);
}
}
#Override
public ShopUsersAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.map_pop_up_item, parent, false);
context=parent.getContext();
itemView.setOnClickListener(this);
return new ShopUsersAdapter.MyViewHolder(itemView);
}
#Override
public void onClick(View v) {
}
public ShopUsersAdapter(List<ShopUsersRecyclerModel> user_list, AdminCheckLocActivity activity) {
this.user_list = user_list;
this.activity=activity;
this.mAdapterCallback = ((AdapterCallback) context);
}
#Override
public void onBindViewHolder(final ShopUsersAdapter.MyViewHolder holder, int position) {
final ShopUsersRecyclerModel user = user_list.get(position);
holder.user.setText(user.getUser_info());
if (user.getUser_type()==3){holder.type.setText("TV Pro.");}
if (user.getUser_type()==4){holder.type.setText("B. Esya Pro.");}
holder.btn_loc.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
mAdapterCallback.onMethodCallback(user.getUser_info());
}
});
}
#Override
public int getItemCount() {
return user_list.size();
}
public interface AdapterCallback {
void onMethodCallback(String userName);
}
}
but i get error
NullPointer at
mAdapterCallback.onMethodCallback(user.getUser_info());
my activity code;
#Override
public void onMethodCallback(final String userName) {
Toast.makeText(this,userName,Toast.LENGTH_LONG).show();
}
and i implement this like ;
implements ShopUsersAdapter.AdapterCallback
userInfo data is not null, i check this. but i need this callback all of my recyclers please help me.

I suggest changing your adapter's constructor to directly receive a callback:
public ShopUsersAdapter(List<ShopUsersRecyclerModel> user_list, AdminCheckLocActivity activity, AdapterCallback callback) {
this.user_list = user_list;
this.activity=activity;
this.mAdapterCallback = callback;
}
You can also make sure your callback isn't null when you're utilizing it:
holder.btn_loc.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// This should be optional for your case
// but it can be useful if you're ever in a situation
// where the callback isn't always available
if(mAdapterCallback != null){
mAdapterCallback.onMethodCallback(user.getUser_info());
}
}
});
And within your Activity, make sure to pass in the callback as an argument when you create your Adapter instance:
// Use 'this' since your Activity implements the callback
ShopUsersAdapter adapter = new ShopUsersAdapter(myList, myActivity, this);

getAdapterPosition not doing what it is supposed to do

I have a RecyclerView Fragment to which I added a Filter Search in an edit text. It works, but when I click in a Card of the Recycler, it goes to the wrong detail. My best guess is that it's getting the wrong position from the getAdapterPosition since let's say I have this list {a,b,c,d,e,f,g,h}. when I filter and get two itmes left like {d,g}. If I click d it redirects to a, if I click g it redirects to b.
This is my RecyclerView
public class RecyclerProfile extends Fragment implements
Adapter.AdapterListener, com.example.cake.profiling.Adapter.SearchListener
{
private RecyclerListener recyclerListener;
private List<Profile> profiles = (new DAOProfile()).getProfile();
private Adapter recyclerAdapter= new Adapter(profiles, this);
public RecyclerProfile() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view= inflater.inflate(R.layout.fragment_recycler_profile,
container, false);
RecyclerView recyclerView = view.findViewById(R.id.recyclerProfile);
EditText editText = view.findViewById(R.id.editText);
editText.addTextChangedListener(new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
}
#Override
public void onTextChanged(CharSequence s, int start, int before, int
count) {
}
#Override
public void afterTextChanged(Editable s) {
filter(s.toString());
}
});
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new
LinearLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setAdapter(recyclerAdapter);
setHasOptionsMenu(true);
return view;
}
private void filter(String text){
ArrayList<Profile> filteredList = new ArrayList<>();
for (Profile profile: profiles){
if (profile.getName().toLowerCase().contains(text.toLowerCase())){
filteredList.add(profile);
}
}
recyclerAdapter.filterList(filteredList);
profiles = new ArrayList<>(filteredList);
}
#Override
public void listen(Profile profile, Integer position) {
recyclerListener.send(profile, position);
}
#Override
public void profileSelected(Profile profile) {
}
//INTERFACE
public interface RecyclerListener {
void send(Profile profile, Integer position);
}
//ON ATTACH
#Override
public void onAttach(Context context) {
super.onAttach(context);
this.recyclerListener = (RecyclerListener) context;
}
}
This is my Adapter
public class Adapter extends RecyclerView.Adapter<Adapter.ProfileViewHolder> {
private List<Profile> profiles;
private AdapterListener adapterListener;
//CONSTRUCTOR
public Adapter(List<Profile> profiles,AdapterListener adapterListener) {
this.profiles = profiles;
this.adapterListener = adapterListener;
}
#NonNull
#Override
public Adapter.ProfileViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
Context context = parent.getContext();
LayoutInflater layoutInflater = LayoutInflater.from(context);
View view = layoutInflater.inflate(R.layout.card_profile, parent, false);
ProfileViewHolder profileViewHolder = new ProfileViewHolder(view);
return profileViewHolder;
}
#Override
public void onBindViewHolder(#NonNull Adapter.ProfileViewHolder holder, int position) {
Profile profile = profiles.get(position);
holder.setter(profile);
}
#Override
public int getItemCount() {
return profiles.size();
}
public void filterList (ArrayList<Profile> filteredList){
profiles = filteredList;
notifyDataSetChanged();
}
//VIEWHOLDER
class ProfileViewHolder extends RecyclerView.ViewHolder{
private ImageView image;
private TextView name;
public ProfileViewHolder(View itemView) {
super(itemView);
name = itemView.findViewById(R.id.nameProfile);
image = itemView.findViewById(R.id.imageProfile);
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Profile profile = profile.get(getAdapterPosition());
adapterListener.receive(profile, getAdapterPosition());
}
});
}
public void setter (Profile profile){
name.setText(profile.getName());
image.setImageResource(profile.getImage());
}
}
public interface AdapterListener {
void receive(Profile profile, Integer position);
}
}

getAdapterPosition()
this will return the position of the item of current data set. This is what I'd do
class ProfileViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
private ImageView image;
private TextView name;
Profile mProfile;
public ProfileViewHolder(View itemView) {
super(itemView);
name = itemView.findViewById(R.id.nameProfile);
image = itemView.findViewById(R.id.imageProfile);
name.setOnClickListener(this);
image.setOnClickListener(this);
}
public void setter (Profile profile){
if(profile != null) {
mProfile = profile;
name.setText(mProfile.getName());
image.setImageResource(mProfile.getImage());
}
}
}
#Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.item_nameProfile:
case R.id.item_imageProfile:
for(int i = 0 ; i < profiles.size() ; i++) {
if(profiles.get(i).getName().equalsIgnoreCase(mProfile.getName()) {
adapterListener.receive(profiles.get(i), i);
break;
}
}
break;
}
}
public interface AdapterListener {
void receive(Profile profile, Integer position);
}
}

Cannot call method of RecyclerView adapter from an activity

I am trying to set the data for recycler view to display from an AsyncTask. I am calling the method setdataEntries from the postExecute of inner class AsyncTask. But the android studio is showing me error could not find the method.
Adapter class
public class EntryAdapter extends RecyclerView.Adapter<EntryAdapter.ViewHolder> {
List<UserTuple> entries;
final private itemClickListener mOnClickListener;
public interface itemClickListener{
void onItemClick(UserTuple utuple);
}
public EntryAdapter(itemClickListener clickhandler) {
mOnClickListener = clickhandler;
}
public void setdataEntries(List<UserTuple> Data) {
entries = Data;
notifyDataSetChanged();
}
#Override
public EntryAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.singleusertuple,parent,false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(EntryAdapter.ViewHolder holder, int position) {
holder.Username.setText(entries.get(position).getUsername());
holder.Password.setText(entries.get(position).getPassword());
}
#Override
public int getItemCount() {
return entries.size();
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
private TextView Username;
private TextView Password;
private CardView card;
public ViewHolder(View itemView) {
super(itemView);
Username = itemView.findViewById(R.id.susername);
Password=itemView.findViewById(R.id.pass);
itemView.setOnClickListener(this);
}
#Override
public void onClick(View v) {
int adapterPosition = getAdapterPosition();
UserTuple ut=new UserTuple(entries.get(adapterPosition).getUsername(),entries.get(adapterPosition).getPassword());
mOnClickListener.onItemClick(ut);
}
}
}
Calling Activity
public class Usertuple extends AppCompatActivity implements EntryAdapter.itemClickListener {
private RecyclerView recyclerView ;
private RecyclerView.Adapter adapater;
private SnapHelper snapHelper;
private List<UserTuple> entries;
private ProgressBar mLoadingIndicator;
private Bundle extras;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_logins);
extras = getIntent().getExtras();
//String site= extras.getString("sitename");
mLoadingIndicator = (ProgressBar) findViewById(R.id.pb_loading_indicator);
Log.i("Logins","Size of returned list "+entries.size());
recyclerView = findViewById(R.id.recycleview);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setHasFixedSize(true);
adapater = new EntryAdapter(this);
recyclerView.setAdapter(adapater);
snapHelper= new LinearSnapHelper();
snapHelper.attachToRecyclerView(recyclerView);
dataView();
}
public void dataView() {
String site= extras.getString("sitename");
recyclerView.setVisibility(View.VISIBLE);
new FetchDataTask().execute(site);
}
#Override
public void onItemClick(UserTuple utuple) {
}
private String key(){
SharedPreferences sharedPref = getSharedPreferences(
"User", this.MODE_PRIVATE);
final String passphrase = sharedPref.getString("userid", "none");
return passphrase;
}
public void showerror(){
recyclerView.setVisibility(View.GONE);
Toast.makeText(this,"Error in retrieving",Toast.LENGTH_SHORT).show();
}
public setdata(List<UserTuple> data){
adapater.setdataEntries(data);
}
public class FetchDataTask extends AsyncTask<String, Void, List<UserTuple>> {
#Override
protected void onPreExecute() {
super.onPreExecute();
mLoadingIndicator.setVisibility(View.VISIBLE);
}
#Override
protected List<UserTuple> doInBackground(String... params) {
/* If there's no zip code, there's nothing to look up. */
if (params.length == 0) {
return null;
}
String site = params[0];
try {
AppDatabase db = Room.databaseBuilder(getApplicationContext(),AppDatabase.class, "production")
.build();
entries =db.entryDao().getSpecific(site);
for(UserTuple ut : entries){
Log.i("password",ut.getPassword());
String st = new Decryption().decrypt(ut.getPassword(),key());
Log.i("After decryption",st);
ut.setPassword(st);
}
return entries;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
#Override
protected void onPostExecute(List<UserTuple> Data) {
mLoadingIndicator.setVisibility(View.INVISIBLE);
if (Data != null) {
adapater.setdataEntries(Data);
} else {
showerror();
}
}
}
}
I want the database calls to be a background task. I don't want the activity to freeze waiting for database calls. Any ideas? Thanks

Declare adapter like
private EntryAdapter adapter;
instead of
private RecyclerView.Adapter adapater;
because RecyclerView.Adapter class does not have any method named setdataEntries but only EntryAdapter class has this method so only the object of type EntryAdapter can call setdataEntries method.
Or you can use down-casting as
((EntryAdapter)adapater).setdataEntries(data);

How pass data from RecyclerView to activity

I need to pass data from recyclerView adapter to main activity on click on image of recyclerview. Can someone help?
public class VideoAdapter extends RecyclerView.Adapter<VideoAdapter.VideoHolder> {
private ArrayList<Video> mData;
private ArrayList<Video> mData2;
private Activity mACtivity;
public VideoAdapter(ArrayList<Video> data, ArrayList<Video> data2, Activity activity) {
this.mData = data;
this.mData2 = data2;
this.mACtivity = activity;
}
#Override
public VideoHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.anteprima_list_item, parent, false);
//view.setOnClickListener(mOnClickListener);
return new VideoHolder(view);
}
#Override
public void onBindViewHolder(VideoHolder holder, int position) {
Video video = mData.get(position);
final Video video2 = mData2.get(position);
holder.setTitolo(video.getTitolo());
holder.setSottoTitolo(video.getSottotitolo());
holder.setData(video.getData());
holder.setData(video.getData());
/* holder.setAddress(restaurant.getAddress());
holder.setCost("Average cost for 2: " + restaurant.getCurrency() + restaurant.getCost());
holder.setRating(restaurant.getRating());*/
Glide.with(mACtivity)
.load(video2.getPic())
.into(holder.restaurantImageView);
holder.restaurantImageView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// handle click event here
System.out.println("PIC"+video2.getPic());
}
});
}
#Override
public int getItemCount() {
if (mData == null)
return 0;
return mData.size();
}
public class VideoHolder extends RecyclerView.ViewHolder {
ImageView restaurantImageView;
TextView restaurantNameTextView;
TextView restaurantAddressTextView;
TextView restaurantRatingTextView;
TextView costTextView;
TextView distanceTextView;
LinearLayout linearlayout;
public VideoHolder(View itemView) {
super(itemView);
linearlayout=(LinearLayout) itemView.findViewById((R.id.linearlayout));
restaurantImageView = (ImageView) itemView.findViewById(R.id.imageview_restaurant);
restaurantNameTextView = (TextView) itemView.findViewById(R.id.textview_restaurant_name);
restaurantAddressTextView = (TextView) itemView.findViewById(R.id.restaurant_address_textview);
distanceTextView = (TextView) itemView.findViewById(R.id.restaurant_distance_textview);
/* costTextView = (TextView) itemView.findViewById(R.id.cost_for_two_textview);
restaurantRatingTextView = (TextView) itemView.findViewById(R.id.rating);*/
}
public void setTitolo(String titolo) {
restaurantNameTextView.setText(titolo);
}
public void setSottoTitolo(String sottotitolo) {
restaurantAddressTextView.setText(sottotitolo);
}
public void setData(String data) {
distanceTextView.setText(data);
}
/* public void setPic(String pic) {
distanceTextView.setText(pic);
}
public void setCost(String cost) {
costTextView.setText(cost);
}
public void setDistance(String distance) {
distanceTextView.setText(distance);
}*/
}
}

Create a listener Interface and let your MainActivity implement it. That way you can call your callback method in your onClick method.
Interface:
public interface OnImageClickListener {
void onImageClick(String imageData);
}
MainActivity:
public class MainActivity implements OnImageClickListener {
#Override
public void onImageClick(String imageData) {
// handle image data
}
//...
}
Your VideoAdapter:
//...
private OnImageClickListener onImageClickListener;
public VideoAdapter(ArrayList<Video> data, ArrayList<Video> data2, Activity activity, OnImageClickListener onImageClickListener) {
this.mData = data;
this.mData2 = data2;
this.mACtivity = activity;
this.onImageClickListener = onImageClickListener;
}
//...
#Override
public void onBindViewHolder(VideoHolder holder, int position) {
//...
holder.restaurantImageView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
onImageClickListener.onImageClick(video2.getPic());
}
});
//...
}
//...

If you want to pass value from onclick to your Parent activity, use onMethodCallback in your MainActivity:
public class MainActivity extends Activity implements AdapterCallback {
private MyAdapter mMyAdapter;
#Override
public void onMethodCallback(String yourValue) {
// get your value here
}
#Override
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.mMyAdapter = new MyAdapter(this);
}
}
In your Adapter:
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private AdapterCallback mAdapterCallback;
public MyAdapter(Context context) {
try {
this.mAdapterCallback = ((AdapterCallback) context);
} catch (ClassCastException e) {
throw new ClassCastException("Activity must implement AdapterCallback.");
}
}
#Override
public void onBindViewHolder(final MyAdapter.ViewHolder viewHolder, final int i) {
// simple example, call interface here
// not complete
viewHolder.itemView.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
mAdapterCallback.onMethodCallback();
}
});
}
public static interface AdapterCallback {
void onMethodCallback(String yourValue);
}
}

If you are working with kotlin, the solution is much simpler.
Original Answer here
pass the lamda val itemClick: (Int) -> Unit to your adapter.
class MyRecyclerViewAdapter(params , val itemClick: (Int) -> Unit): RecyclerView.Adapter<RecyclerView.ViewHolder>() {
internal inner class MyViewHolder(view: View) : RecyclerView.ViewHolder(view) {
...
itemView.setOnClickListener( {itemClick(layoutPosition)} )
}
}
In your Activity use the returned value position
val myAdapter = MyRecyclerViewAdapter(params) { position ->
// do something
}

Write interface in your adapter like bellow :
interface clickItemListener {
void onItemClick(String order);
}
And your constructor should be :
privat clickItemListener clickItemListeners;
public VideoAdapter(ArrayList<Video> data, ArrayList<Video> data2, Activity activity, clickItemListener clickItemListeners) {
this.mData = data;
this.mData2 = data2;
this.mACtivity = activity;
this.clickItemListeners = clickItemListeners;
}
Then you can pass to Activity :
yourLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
clickItemListeners.onItemClick(yourValue);
}
});
And implement your interface in your activity like bellow :
public class yourActivity extends AppCompatActivity implements
YourAdapter.clickItemListener{
#Override
public void onItemClick(String order) {
//You can get your value here
}
}
Remember that you should pass activity to adapter like bellow :
YourAdapter adapter = new YourAdapter (... , ... , ... , activity.this);

how to use Architecture Components ViewModel inside RecyclerView Adapter?

I have multiple ViewHolders that work as separated views inside a vertical RecyclerView. I'm practicing with the new Architecture Components ViewModel.
Inside my ViewModel I have a couple of MutableLiveData lists that i want to observe, but how can I call
ViewModelProviders.of((AppCompatActivity)getActivity()).get(FilterViewModel.class)
and
mFilterViewModel.getCountries().observe(this, new Observer<ArrayList<TagModel>>() {
#Override
public void onChanged(#Nullable ArrayList<TagModel> tagModels) {
}
});
without leaking the activity or save the activity inside the adapter?
my ViewModel
public class FilterViewModel extends ViewModel {
private final MutableLiveData<ArrayList<TagModel>> mCountries;
private final MutableLiveData<ArrayList<TagModel>> mSelectedCountryProvinceList;
private final MutableLiveData<ArrayList<TagModel>> mDistanceList;
public FilterViewModel(){
mCountries = new MutableLiveData<>();
mSelectedCountryProvinceList = new MutableLiveData<>();
mDistanceList = new MutableLiveData<>();
TagStore.getInstance().subscribe(new StoreObserver<TagSearchList>() {
#Override
public void update(TagSearchList object) {
mCountries.setValue(object.getCountries());
}
#Override
public void update(int id, TagSearchList object) {
if (id == 5){
TagStore.getInstance().unSubcribe(this);
update(object);
}
}
#Override
public void error(String error) {
}
}).get(5,"parent");
TagStore.getInstance().subscribe(new StoreObserver<TagSearchList>() {
#Override
public void update(TagSearchList object) {
mSelectedCountryProvinceList.setValue(object.toList());
}
#Override
public void update(int id, TagSearchList object) {
if (id == 6){
TagStore.getInstance().unSubcribe(this);
update(object);
}
}
#Override
public void error(String error) {
}
}).get(6,"parent");
TagStore.getInstance().subscribe(new StoreObserver<TagSearchList>() {
#Override
public void update(TagSearchList object) {
mDistanceList.setValue(object.toList());
}
#Override
public void update(int id, TagSearchList object) {
if (id == 51){
TagStore.getInstance().unSubcribe(this);
update(object);
}
}
#Override
public void error(String error) {
}
}).get(51,"parent");
}
public void selectCountry(final TagModel country){
TagStore.getInstance().subscribe(new StoreObserver<TagSearchList>() {
#Override
public void update(TagSearchList object) {
mSelectedCountryProvinceList.setValue(object.toList());
}
#Override
public void update(int id, TagSearchList object) {
if (id == country.getId()){
TagStore.getInstance().unSubcribe(this);
update(object);
}
}
#Override
public void error(String error) {
}
}).get(country.getId(),"parent");
}
public LiveData<ArrayList<TagModel>> getCountries(){
return mCountries;
}
public LiveData<ArrayList<TagModel>> getDistances(){
return mDistanceList;
}
public LiveData<ArrayList<TagModel>> getProvinces(){
return mSelectedCountryProvinceList;
}

I am using Room Persistence library. Below is my code for recyclerview adapter using MVVM.
You can see CartViewModel and I have initialized it into the constructor. The constructor gets the context from the activity, and I have cast it into FragmentActivity.
private CartViewModel cartViewModel;
public CartListAdapter(Context context, List<CartModel> cartModels) {
this.context = context;
this.cartModels = cartModels;
cartViewModel = ViewModelProviders.of((FragmentActivity) context).get(CartViewModel.class);
}
Here is my full adapter class. I hope it will help.
public class CartListAdapter extends RecyclerView.Adapter<CartListAdapter.CartListViewHolder> {
private static final String TAG = "CartListAdapter";
private Context context;
private List<CartModel> cartModels;
private Double totalQuantity = 0.0;
private CartViewModel cartViewModel;
public CartListAdapter(Context context, List<CartModel> cartModels) {
this.context = context;
this.cartModels = cartModels;
cartViewModel = ViewModelProviders.of((FragmentActivity) context).get(CartViewModel.class);
}
#NonNull
#Override
public CartListViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
return new CartListViewHolder(LayoutInflater.from(context).inflate(R.layout.list_all_cart_item,parent,false));
}
#Override
public void onBindViewHolder(#NonNull CartListViewHolder holder, int position) {
CartModel cartModel = cartModels.get(position);
Glide.with(context)
.load(cartModel.getPPICLocate())
.into(holder.cartItemImage);
holder.tvCartProductName.setText(cartModel.getProductName());
holder.tvCartProductCategory.setText(cartModel.getPCategorySubID());
holder.tvCartProductPrice.setText(cartModel.getPPriceSales());
holder.etCartProductQuantity.setText(cartModel.getPQuantity());
holder.btnCartPQtIncrease.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
totalQuantity = Double.valueOf(holder.etCartProductQuantity.getText().toString());
totalQuantity = totalQuantity+1;
cartModel.setPQuantity(totalQuantity.toString());
updateCart(cartModel);
}
});
holder.btnCartPQtDecrease.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
totalQuantity = Double.valueOf(holder.etCartProductQuantity.getText().toString());
totalQuantity = totalQuantity-1;
cartModel.setPQuantity(totalQuantity.toString());
updateCart(cartModel);
}
});
}
#Override
public int getItemCount() {
return cartModels.size();
}
public class CartListViewHolder extends RecyclerView.ViewHolder{
private ImageView cartItemImage;
private TextView tvCartProductName,tvCartProductCategory,tvCartProductPrice,
etCartProductQuantity,tvCartProductPrevPrice;
private ImageButton btnCartPQtIncrease,btnCartPQtDecrease;
public CartListViewHolder(#NonNull View itemView) {
super(itemView);
cartItemImage= itemView.findViewById(R.id.cartItemImage);
tvCartProductName= itemView.findViewById(R.id.tvCartProductName);
tvCartProductCategory= itemView.findViewById(R.id.tvCartProductCategory);
tvCartProductPrice= itemView.findViewById(R.id.tvCartProductPrice);
etCartProductQuantity= itemView.findViewById(R.id.etCartProductQuantity);
tvCartProductPrevPrice= itemView.findViewById(R.id.tvCartProductPrevPrice);
btnCartPQtIncrease= itemView.findViewById(R.id.btnCartPQtIncrease);
btnCartPQtDecrease= itemView.findViewById(R.id.btnCartPQtDecrease);
}
}
public void addItems(List<CartModel> cartModels) {
this.cartModels = cartModels;
notifyDataSetChanged();
}
private void updateCart(CartModel cartModel){
String tqt = String.valueOf(cartModel.getPQuantity());
Log.d(TAG, "updateQuantity: "+tqt);
/*cartRepository.updateCartRepo(cartModel);*/
cartViewModel.updateCartItemVM(cartModel);
}
}

You could create an OnClickListener interface instead, then implement the onClick method (defined in your interface) in your fragment or activity where you have access to your view model.

My solution to this issue is;
create a new variable(ViewModel) for the layout (fragment or activity layout)
in your activity or fragment get the instance of your viewModel with ViewModelProviders
hold the data which fills your recyclerView in MutableLiveData and observe it and fill the adapter of recyclerView with the value you observed
here you mut be careful not to create adapter instance in observe method.
if you create it in observe method, it will make leaks