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How to setOnClickListener in adapter using RecyclerView to display inside fragment

I cannot access the ID of the item to view it in ToastMessage, or even store it in the database (use Room DataBase)
I have tried but the message does not appear
I need the reference ID to use for database storage and complete the process for storing the shopping cart
itemAdapter.java
public class itemAdapter extends RecyclerView.Adapter<itemAdapter.ItemViewHolder> {
private Context context;
private ArrayList<Items> arrayList;
private AdapterView.OnItemClickListener listener;
public itemAdapter(Context context, ArrayList<Items> arrayList) {
this.context = context;
this.arrayList = arrayList;
}
#NonNull
#Override
public ItemViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(context).inflate(R.layout.item, parent, false);
return new ItemViewHolder(v);
}
#Override
public void onBindViewHolder(#NonNull ItemViewHolder holder, int position) {
holder.name.setText(arrayList.get(position).getItemName());
holder.desc.setText(arrayList.get(position).getItemDesc());
holder.price.setText(arrayList.get(position).getItemPrice());
holder.add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(context,arrayList.get(position).getItemIid(),Toast.LENGTH_SHORT);
}
});
holder.name.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(context,arrayList.get(position).getItemPrice(),Toast.LENGTH_SHORT);
}
});
}
#Override
public int getItemCount() {
return arrayList.size();
}
class ItemViewHolder extends RecyclerView.ViewHolder {
TextView name, desc, price;
ImageView remove, add;
public ItemViewHolder(#NonNull View itemView) {
super(itemView);
name = itemView.findViewById(R.id.tvName);
desc = itemView.findViewById(R.id.tvDesc);
price = itemView.findViewById(R.id.tvPrice);
remove = itemView.findViewById(R.id.btnDelete);
add = itemView.findViewById(R.id.btnAdd);
}
}
}
MealsFragment.java
public class MealsFragment extends Fragment {
public MealsFragment() {
// Required empty public constructor
}
RecyclerView recyclerView;
itemAdapter adapter;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_meals, container, false);
}
#Override
public void onViewCreated( View view, Bundle savedInstanceState) {
ArrayList<Items> ItemsList = (ArrayList<Items>) RoomDatabaseSingleton.getInstance(getContext().getApplicationContext())
.getAppDatabase()
.getDao()
.getItems("meals");
recyclerView = view.findViewById(R.id.rvMeals);
RecyclerView.LayoutManager manager = new LinearLayoutManager(
getContext(), RecyclerView.VERTICAL, false);
recyclerView.setLayoutManager(manager);
adapter = new itemAdapter(getContext(), ItemsList);
recyclerView.setAdapter(adapter);
}
}

Try the following instead
holder.add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(context,arrayList.get(position).getItemIid(),Toast.LENGTH_SHORT).show();
}
});
holder.name.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(context,arrayList.get(position).getItemPrice(),Toast.LENGTH_SHORT).show();
}
});
The static method makeText of Toast is used to create the Toast object and show() method on the Toast object is used to display the Toast

Made a custom Adapter for my RecyclerView with a List

I want to make a custom Adapter for my RecyclerView because I need to use a custom method inside who will init my List later when my presenter will be ready:
public void setList(List<Object> data){
this.data = data;
}
This is my not custom interface for my Adapter without implementation.
final class AdapterReviews extends RecyclerView.Adapter<AdapterReviews.ReviewViewHolder> {}
The question is how should be the interface for my custom Adapter?

**public class GetHolidaylistAdapter extends RecyclerView.Adapter<GetHolidaylistAdapter.ViewHolder> {
ArrayList<HashMap<String, String>> arrayList;
public GetHolidaylistAdapter(ArrayList<HashMap<String, String>> arrayList) {
this.arrayList = arrayList;
}
public class ViewHolder extends RecyclerView.ViewHolder {
TextView holiyDay_Date_Tv, holidayName_tv, holidayType_tv, day_tv;
public ViewHolder(View itemView) {
super(itemView);
holiyDay_Date_Tv = (TextView) itemView.findViewById(R.id.holiyDay_Date_Tv);
holidayName_tv = (TextView) itemView.findViewById(R.id.holidayName_tv);
holidayType_tv = (TextView) itemView.findViewById(R.id.holidayType_tv);
}
}
#Override
public int getItemCount() {
return arrayList.size();
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
GetHolidaylistAdapter.ViewHolder viewHolder = null;
Log.d(TAG, "Rv_Child_Active.." + viewType);
viewHolder = new GetHolidaylistAdapter.ViewHolder(LayoutInflater.from(parent.getContext()).
inflate(R.layout.holiday_child_rv, parent, false));
return viewHolder;
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
String date = arrayList.get(position).get(TAG_HOLIDAYDATE);
holder.holidayName_tv.setText(arrayList.get(position).get(TAG_HOLIDAYName));
holder.holiyDay_Date_Tv.setText(arrayList.get(position).get(TAG_HOLIDAYDATE));
holder.holidayType_tv.setText(arrayList.get(position).get(TAG_HOLIDAYtype));
***}
}
recycle_view=(RecyclerView)findViewById(R.id.recycle_view);
linearLayoutManager=new LinearLayoutManager(this);
recycle_view.setLayoutManager(linearLayoutManager);
adapter=new CustomAdapter(modelRecyclerArrayList);
recycle_view.setAdapter(adapter);
RecyclerView recycle_view;
LinearLayoutManager linearLayoutManager;
CustomAdapter adapter;
ArrayList<ModelRecycler> modelRecyclerArrayList = new ArrayList<>();*

A basic RecyclerView CustomAdapter looks like this
public class CustomAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private final Context context;
ArrayList<String> list = new ArrayList<>();
public CustomAdapter(Context context, ArrayList<String> list) { // you can pass other parameters in constructor
this.context = context;
this.list = list;
}
private class CustomAdapterItemView extends RecyclerView.ViewHolder {
final TextView textView;
CustomAdapterItemView(final View itemView) {
super(itemView);
textView = (TextView) itemView;
}
void bind(int position) {
textView.setText("");
}
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return new CustomAdapterItemView(LayoutInflater.from(context).inflate(R.layout.item_color, parent, false));
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
((CustomAdapterItemView) holder).bind(position);
}
#Override
public int getItemCount() {
return list.size();
}
// Add your other methods here
}

You can check this. Here you have complete example of RecyclerView. It is all made by Google.

How to add a recyclerview item dynamically when click a button in another activity?

I have a recyclerview in ShoppingCartActivity and a button in ProductDetailActivity. I want to send some data to ShoppingCartActivity when a button clicked in ProductDetailActivity and display them in recyclerview item that creates dynamically in ShoppingCartActivity.
I added addData method to recyclerview Adapter but it doesn't work and app crashes.
shop_btn = findViewById(R.id.add_to_shopping_cart);
shop_btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent addToCart = new Intent(ProductDetailActivity.this, ShoppingCartActivity.class);
startActivity(addToCart);
}
});
//HERE IS MY RECYCLERVIEW ADAPTER
public class RecyclerViewAdapter_ShoppingCart extends RecyclerView.Adapter<RecyclerViewAdapter_ShoppingCart.MyViewHolder> {
private Context context;
List<CartItems> cartItemsList;
public RecyclerViewAdapter_ShoppingCart(Context context, List<CartItems> cartItemsList) {
this.context = context;
this.cartItemsList = cartItemsList;
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view;
LayoutInflater layoutInflater = LayoutInflater.from(context);
view = layoutInflater.inflate(R.layout.card_cart, parent, false);
return new MyViewHolder(view);
}
#NonNull
#Override
public void onBindViewHolder(#NonNull final MyViewHolder holder, final int position) {
holder.cart_title.setText(cartItemsList.get(position).getTitle());
holder.cart_price.setText(cartItemsList.get(position).getPrice());
Picasso.get().load(cartItemsList.get(position).getImageUrl()).into(holder.cart_img);
}
#Override
public int getItemCount() {
return cartItemsList.size();
}
public static class MyViewHolder extends RecyclerView.ViewHolder {
TextView cart_title, cart_price;
ImageView cart_img;
public MyViewHolder(View itemView) {
super(itemView);
cart_title = itemView.findViewById(R.id.cart_title);
cart_price = itemView.findViewById(R.id.cart_price);
//cart_delete = itemView.findViewById(R.id.cart_delete);
cart_img = itemView.findViewById(R.id.cart_image);
}
}
public void addItem(List<CartItems> cartItems) {
CartItems newValue = new CartItems();
newValue.setTitle("123");
newValue.setPrice("123");
newValue.setImageUrl("");
cartItems.add(newValue);
notifyDataSetChanged();
}
}
My goal is adding recyclerview items dynamically to ShoppingCartActivity when a button clicked in ProductDetailActivity but app crashes.

RecyclerView problem to load more than n items

I've implementend a RecyclerView as follow
The Adapter with the Holder
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyHolder> {
#NonNull
#Override
public MyHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.indovinelloelement,parent,false);
MyHolder holder = new MyHolder(view);
return holder;
}
#Override
public void onBindViewHolder(#NonNull MyHolder holder, int position) {
holder.category.setText(data.get(position).getCategory());
holder.difficulty.setText(""+data.get(position).getDifficulty());
holder.title.setText(data.get(position).getTitle());
holder.score.setText(""+data.get(position).getScore());
if(data.get(position).isLocked())
holder.setLocked();
else
holder.setUnlocked();
}
public DataGestour.Indovinello getIndovinello(int pos){
return data.get(pos);
}
#Override
public int getItemCount() {
return data.size();
}
public class MyHolder extends RecyclerView.ViewHolder {
public TextView category,score,difficulty,title;
private ImageView lock_state;
public MyHolder(View itemView) {
super(itemView);
category = (TextView)itemView.findViewById(R.id.categoria);
score = (TextView)itemView.findViewById(R.id.punteggio);
difficulty = (TextView) itemView.findViewById(R.id.difficolta);
title = (TextView)itemView.findViewById(R.id.titolo);
lock_state = (ImageView) itemView.findViewById(R.id.lock_state);
}
public void setLocked(){
lock_state.setImageResource(R.drawable.ic_lock_outline_black_24dp);
}
public void setUnlocked(){
lock_state.setImageResource(R.drawable.ic_lock_open_black_24dp);
}
}
ArrayList<DataGestour.Indovinello> data;
Context context;
public MyAdapter(Context context, ArrayList<DataGestour.Indovinello> list){
this.context = context;
this.data = list;
}
}
and the RecyclerView:
rc = (RecyclerView)root_view.findViewById(R.id.lista_domande);
rc.setHasFixedSize(true);
LinearLayoutManager ly = new LinearLayoutManager(getContext());
ly.setOrientation(LinearLayoutManager.VERTICAL);
rc.setLayoutManager(ly);
try{
gestour = new DataGestour(getContext());
}catch (IllegalStateException e){
Log.e("DataManager",e.getMessage());
};
adapter = new MyAdapter(getContext(),gestour.getAllDatas());
rc.setAdapter(adapter);
adapter.notifyDataSetChanged();
where DataGestoure is a class that manipulates some data from a
database and store them in a ArrayList (DataGestour.getAllDatas is the method to return the data under a ArrayList)
The problem start only if the ArrayList contains more then 3 items becouse the RecyclerView doen't show them despite the fact that the adapter holds all the data in ArrayList< DataGestour.Indovinello > data

Well, you need a little more order in your code, since it is not properly structured, by default the RecyclerView has its Scrolleable view unless in the XML this attribute is removed, well I recommend that you use this code in your adapter and use a model to save the information you get from your BD, that is the correct way to work to keep everything in order and it is easier to work it, once this is done you can use this code perfectly that I am sure will work, remember to only pass information to my Model that in my case calls it "Model" and with this the error of your data load will be solved. It is also advisable to use a List <> for these cases since the Arrays <> tend to have errors when you manipulate the data and more if you do it the way you present the code.
private List<Model> mDataList;
public MyAdapter(Context context){
this.context = context;
this.mDataList = new ArrayList<>();
}
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyHolder> {
#NonNull
#Override
public MyHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.indovinelloelement,parent,false);
return new MyHolder(view);
}
#Override
public void onBindViewHolder(#NonNull MyHolder holder, int position) {
MyHolder holder = (MyHolder) MyHolder;
hoder.bind(mDataList.getPosition(position));
}
#Override
public int getItemCount() {
return mDataList.size();
}
public void setData(List<Model> list) {
mDataList.clear();
mDataList.addAll(list);
notifyDataSetChanged();
}
public class MyHolder extends RecyclerView.ViewHolder {
TextView category;
category = (TextView)itemView.findViewById(R.id.categoria);
TextView score;
score = (TextView)itemView.findViewById(R.id.punteggio);
TextView difficulty;
difficulty = (TextView) itemView.findViewById(R.id.difficolta);
TextView title;
title = (TextView)itemView.findViewById(R.id.titolo);
ImageView lock_state;
lock_state = (ImageView) itemView.findViewById(R.id.lock_state);
public MyHolder(View itemView) {
super(itemView);
}
protected void bind(Model model){
category.setText(model.getCategory());
score.setText(model.getScore());
difficulty.setText(model.getDifficulty());
title.setText(model.getTitle());
if(model.isLocked()){
lock_state.setImageResource(R.drawable.ic_lock_outline_black_24dp);
} else {
lock_state.setImageResource(R.drawable.ic_lock_open_black_24dp);
}
}
}
}
And for your class that contains the RecyclerView use the code as follows.
RecyclerView mRecyclerView;
mRecyclerView = (RecyclerView)root_view.findViewById(R.id.lista_domande);
private MyAdapter mAdapter;
private List<Model> mDataList;
private DataGestour gestour;
private void setupRecyclerView(){
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getContext());
linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
mRecyclerView.setHasFixedSize(true);
mRecyclerView.setLayoutManager(linearLayoutManager);
mAdapter = new MyAdapter(getContext());
mRecyclerView.setAdapter(mAdapter);
mRecyclerView.setData(mDataList);
}
private void getDataDB(){
mDataList.add(gestour.getAllDatas);
}

Displaying recyclerView on MainActivity

I'm trying to display my recyclerView on MainActivity, but can't seem to do it.
This is my code: (which compiles with no errors)
private RecyclerView recyclerView;
private MyAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = (RecyclerView) this.findViewById(R.id.recycler_view_example);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
adapter = new MyAdapter(this, getData());
recyclerView.setAdapter(adapter);
// Add Code to display recyclerView on Main...
}
// This is not my actual data, just testing it out
public static List<Block> getData() {
List<Block> data = new ArrayList<>();
String[] ids = {"310", "313", "320"};
String[] names = {"name of three ten", "name of three thirteen", "name of three twenty"};
for (int i=0; i<ids.length; i++) {
data.add(new Block(ids[i], names[i]));
}
return data;
}
And myActivity Class:
private final LayoutInflater inflater;
// Data: (information)
List<Block> data = new ArrayList<>();
public MyAdapter(Context context, List<Block> data) {
inflater = LayoutInflater.from(context);
this.data = data;
}
#Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = inflater.inflate(R.layout.block, parent, false);
MyViewHolder holder = new MyViewHolder(view);
return holder;
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder h, int position) {
MyViewHolder holder = new MyViewHolder(h.itemView);
Block current = data.get(position);
holder.id.setText(current.getId());
holder.name.setText(current.getName());
}
#Override
public int getItemCount() {
return 0;
}
class MyViewHolder extends RecyclerView.ViewHolder {
TextView id;
TextView name;
Button button;
// Constructor
public MyViewHolder(View itemView) {
super(itemView);
id = (TextView) itemView.findViewById(R.id.the_course_id);
name = (TextView) itemView.findViewById(R.id.course_name);
button = (Button) itemView.findViewById(R.id.click);
}
}
}
All I'm trying to do now is that when I run the emulator, I will see the contents of the recyclerView. But, I've been stuck on this for a while as nothing seems to work.
Mind you I'm a beginner with Android, so forgive me if this is very trivial.

You should return the number of items in your list, within getItemCount as in:
#Override
public int getItemCount() {
return data.size();
}

Ok here you need to change the following: update -
recyclerView.setLayoutManager(new LinearLayoutManager(this));
to
recyclerView.setLayoutManager(new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false));
and in adapter class change:
#Override
public int getItemCount() {
return data.size();
}
thats it. Happy coding :)

Change onBindViewHolder to:
#Override
public void onBindViewHolder(RecyclerView.ViewHolder h, int position) {
Block current = data.get(position);
h.id.setText(current.getId());
h.name.setText(current.getName());
}
also add #SelçukCihan solution to this
EDIT
Also if you want to use your MyViewHolder you have to change the following:
First change class signature:
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder>
and also change the signature for onBindViewHolder:
public void onBindViewHolder(MyViewHolder h, int position)
and finally change the signature of your MyViewHolder class:
static class MyViewHolder extends RecyclerView.ViewHolder