how to use Architecture Components ViewModel inside RecyclerView Adapter?

Question

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; } 

Answer 1

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);  }  } 

Answer 2

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.