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How to solve position problem in adapter? Using firebase as the backend

I'm creating an app with firebase as a backend. I'm using same adapter for different activity, now it is working good but positions were mismatched for example: The output of position 0 shows in position 1 and for position 1 shows in position 2 and so on.. How to solve this problem, The problem with the positions of the output.
Adapter:
public class FrontlistAdapter extends FirebaseRecyclerAdapter<Gamedata, FrontlistAdapter.ViewHolder> {
private static final String TAG = "GameAdapter";
Context mContext;
int positions;
public FrontlistAdapter(#NonNull FirebaseRecyclerOptions<Gamedata> options, Context context) {
super(options);
mContext = context;
}
#Override
protected void onBindViewHolder(#NonNull ViewHolder holder, int position, #NonNull Gamedata model) {
holder.name.setText(model.getName());
holder.address.setText(model.getAddress());
//Picasso.get().load(model.getFrontcover()).into(holder.Frontcover);
Glide.with(mContext).load(model.getFrontcover()).into(holder.Frontcover);
positions = position; //<-- here I'm having positions but output shows different for each positions
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());
View v = layoutInflater.inflate(R.layout.gamerow,parent,false);
ViewHolder viewHolder = new ViewHolder(v);
return viewHolder;
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
ImageView Frontcover;
TextView name;
TextView address;
View v;
public ViewHolder(#NonNull View itemView) {
super(itemView);
Frontcover = (ImageView)itemView.findViewById(R.id.frontcover);
name = (TextView)itemView.findViewById(R.id.frontname);
address=(TextView)itemView.findViewById(R.id.frontaddress);
v = itemView;
itemView.setClickable(true);
itemView.setOnClickListener((View.OnClickListener) this);
}
#Override
public void onClick(View v) {
String className = mContext.getClass().getSimpleName();
Intent intent = null;
switch (className) {
case "GameActivity":
intent = new Intent(mContext, Center_details.class);
intent.putExtra("User", getRef(positions).getKey());
break;
case "KidsActivity":
intent = new Intent(mContext,AllCenterDetails.class);
intent.putExtra("Kids",getRef(positions).getKey());
break;
}
mContext.startActivity(intent);
}
}
}

first what you have to do is create the interface like this
public interface ClickListner {
void onClick(View view, int position);
}
then in your activity create object of the interface like this and pass to the adapter along with your other data
ClickListner listener = ClickListner();
FrontlistAdapter customAdapter = new
FrontlistAdapter(AcceptedOrdersActivity.this,listener);
riderView.setAdapter(customAdapter);
copy this outside onCreate and intent in this
private ClickListner ClickListner() {
ClickListner listener = new ClickListner() {
#Override
public void onClick(View view, int position) {
int tag = (int) view.getTag();
if(tag == 0)
{
//Intent here
}
}
};
return listener;
}
now your adapter should be this one
public class FrontlistAdapter extends
RecyclerView.Adapter<FrontlistAdapter .DataObjectHolder>{
ClickListner listenr;
Context context;
public FrontlistAdapter (Context context,ClickListner listenr) {
this.context = context;
this.listenr = listenr;
}
public static class DataObjectHolder extends RecyclerView.ViewHolder {
Context context;
public DataObjectHolder(View itemView,ClickListner listenr) {
super(itemView);
this.listenr = listenr;
Frontcover = (ImageView)itemView.findViewById(R.id.frontcover);
name = (TextView)itemView.findViewById(R.id.frontname);
address=(TextView)itemView.findViewById(R.id.frontaddress);
v = itemView;
setOnClickListeners();
}
private void setOnClickListeners() {
`v.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
v.setTag(0);
listenr.onClick(v, getAdapterPosition());
}
});
}
}
#NonNull
#Override
public FrontlistAdapter.DataObjectHolder onCreateViewHolder(#NonNull ViewGroup parent,
int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.cell_orderdetail_list, parent, false);
FrontlistAdapter.DataObjectHolder dataObjectHolder = new
FrontlistAdapter.DataObjectHolder(view,listenr);
return dataObjectHolder;
}
#Override
public void onBindViewHolder(#NonNull FrontlistAdapter.DataObjectHolder holder, int
position) {
}
#Override
public int getItemCount() {
return options.size;
}
}

positions = position;
This is your problem. You're setting one global position for everything in the adapter.
Everywhere you are currently using position, you should instead be calling getBindingAdapterPosition() on the ViewHolder.

I'd like to implement a recycler view click event

I want to implement a recycler view click event. I intended to have an event when I clicked tvRoomNum. But error 'TextView.setOnClickListener(android.view.View$OnClickListener)' on a null object reference' occurs. So I notice that tvRoomNum is null object and attempt to use 'findViewById'. But the function is not recognized. How can I solve the problem?
public class RoomAdapter extends RecyclerView.Adapter<RoomAdapter.CustomViewHolder> {
private Context context;
private ArrayList<RoomData> rooms;
public ArrayList<StudnetInRoomData> students;
private LayoutInflater inflater;
private RoomData room;
View view;
public RoomAdapter(Context context, ArrayList<RoomData> rooms) {
this.context = context;
this.rooms = rooms;
this.inflater = LayoutInflater.from(context);
students = new ArrayList<>();
}
#Override
public CustomViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
view = inflater.inflate(R.layout.single_room, parent, false);
return new CustomViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull CustomViewHolder holder, int position) {
room = rooms.get(position);
holder.tvRoomNum.setText(String.valueOf(room.roomNum));
}
#Override
public int getItemCount() {
return rooms.size();
}
public class CustomViewHolder extends RecyclerView.ViewHolder {
public TextView tvRoomNum;
public CustomViewHolder(View itemView) {
super(itemView);
tvRoomNum.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View view) {
Intent intent = new Intent(view.getContext(), PlusStudentActivity.class);
intent.putExtra("studentList", room.students);
context.startActivity(intent);
}
});
}
}
}
The code below is the adapter of the recycler view that implements the recycler view. This is a dual recircular view structure.
public class FloorAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> implements OnFloorItemClickListener {
OnFloorItemClickListener listener;
static public ArrayList<FloorData> floors;
private Context context;
private LayoutInflater layoutInflater;
private OnItemClickListener mListener = null;
public FloorAdapter(ArrayList<FloorData> floors, Context context) {
this.floors = floors;
this.context = context;
this.layoutInflater = LayoutInflater.from(context);
}
public interface OnItemClickListener{
void onItemClick(View v, int pos);
}
public void setOnItemClickListener(OnItemClickListener listener) {
this.mListener = listener ;
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = layoutInflater.inflate(R.layout.signle_floor, parent, false);
return new GridViewHolder(view);
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
((GridViewHolder)holder).recyclerView.setAdapter(new RoomAdapter(context, floors.get(position).rooms));
((GridViewHolder)holder).recyclerView.setLayoutManager(new GridLayoutManager(context, 5));
((GridViewHolder)holder).recyclerView.setHasFixedSize(true);
((GridViewHolder)holder).tvFloorNum.setText(String.valueOf(floors.get(position).floorNum));
}
#Override
public int getItemCount() {
return floors.size();
}
#Override public void onItemClick(RecyclerView.ViewHolder holder, View view, int position) {
if(listener != null){
listener.onItemClick(holder,view,position);
}
}
#Override
public int getItemViewType(int position) {
return floors.get(position).id;
}
public class GridViewHolder extends RecyclerView.ViewHolder {
RecyclerView recyclerView;
TextView tvFloorNum;
Button btnPlusRoom;
public GridViewHolder(View itemView) {
super(itemView);
recyclerView = itemView.findViewById(R.id.rvRooms);
tvFloorNum = itemView.findViewById(R.id.tvFloorNum);
btnPlusRoom = (Button)itemView.findViewById(R.id.btnPlusRoom);
btnPlusRoom.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v)
{
int pos = getAdapterPosition();
if (pos != RecyclerView.NO_POSITION)
{
if(mListener != null){
mListener.onItemClick(v, pos);
}
}
}
});
}
}
}

Your TextView is null, because you are missing the findViewById():
You find the Id on a View, in this case, it is the itemView
The function was not recognised because you would've just called findViewById() & ViewHolder does not have that method,
You should've called itemView.findViewById() instead.
Try this:
public class CustomViewHolder extends RecyclerView.ViewHolder {
public TextView tvRoomNum;
public CustomViewHolder(View itemView) {
super(itemView);
tvRoomNum = itemView.findViewById(R.id.your_textview_id) // THIS
tvRoomNum.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View view) {
Intent intent = new Intent(view.getContext(), PlusStudentActivity.class);
intent.putExtra("studentList", room.students);
context.startActivity(intent);
}
});
}
}

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.

Picasso - can't find "context"

First of all, I am a beginner and this may be a stupid question for you. I need to pass context to the following code in order to load an image in the recyclerview. Tried several options but any of them is not a success. My problem is how to find the context that to pass in the following code.
Picasso.with(context here).load("http://i.imgur.com/DvpvklR.png").into(thumbnail);
Here is the full code which causes the problem(I am trying to pass an image to an recyclerview)
public class WishListAdapter extends RecyclerView.Adapter<WishListAdapter.DerpHolder> {
private List<WishListItem> listData;
private LayoutInflater inflater;
public WishListAdapter(List<WishListItem> listData, Context c) {
inflater = LayoutInflater.from(c);
this.listData = listData;
}
#Override
public WishListAdapter.DerpHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = inflater.inflate(R.layout.wish_list_item, parent, false);
return new DerpHolder(view);
}
#Override
public void onBindViewHolder(DerpHolder holder, int position) {
}
public void setListData(ArrayList<WishListItem> exerciseList) {
this.listData.clear();
this.listData.addAll(exerciseList);
}
#Override
public int getItemCount() {
return listData.size();
}
class DerpHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
ImageView thumbnail;
TextView title;
TextView subTitle;
View container;
public DerpHolder(View itemView) {
super(itemView);
thumbnail = itemView.findViewById(R.id.im_item_icon);
//subTitle = itemView.findViewById(R.id.lbl_item_sub_title);
//title = itemView.findViewById(R.id.lbl_item_text);
container = itemView.findViewById(R.id.cont_item_root);
container.setOnClickListener(this);
Picasso.with(context ).load("http://i.imgur.com/DvpvklR.png").into(thumbnail);
}
#Override
public void onClick(View v) {
Log.d("janitha", "item clicked");
}
Also I have read following too:-Picasso and context
Expect help from somebody.

You haven't saved context from your constructor. Do as like as this:
public class WishListAdapter extends
RecyclerView.Adapter<WishListAdapter.DerpHolder> {
private List<WishListItem> listData;
private LayoutInflater inflater;
Context context;
public WishListAdapter(List<WishListItem> listData, Context c) {
inflater = LayoutInflater.from(c);
this.listData = listData;
this.context = c;
}
#Override
public WishListAdapter.DerpHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = inflater.inflate(R.layout.wish_list_item, parent, false);
return new DerpHolder(view);
}
#Override
public void onBindViewHolder(DerpHolder holder, int position) {
}
public void setListData(ArrayList<WishListItem> exerciseList) {
this.listData.clear();
this.listData.addAll(exerciseList);
}
#Override
public int getItemCount() {
return listData.size();
}
class DerpHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
ImageView thumbnail;
TextView title;
TextView subTitle;
View container;
public DerpHolder(View itemView) {
super(itemView);
thumbnail = itemView.findViewById(R.id.im_item_icon);
//subTitle = itemView.findViewById(R.id.lbl_item_sub_title);
//title = itemView.findViewById(R.id.lbl_item_text);
container = itemView.findViewById(R.id.cont_item_root);
container.setOnClickListener(this);
Picasso.with(context ).load("http://i.imgur.com/DvpvklR.png").into(thumbnail);
}
#Override
public void onClick(View v) {
Log.d("janitha", "item clicked");
}

Try,
private Context context;
and in your constructor,
this.context = c;
now you can use 'context' as a parameter.

Modify your code as following:
private List<WishListItem> listData;
private LayoutInflater inflater;
private Context mContext;
public WishListAdapter(List<WishListItem> listData, Context c) {
inflater = LayoutInflater.from(c);
this.listData = listData;
this.mContext = c;
}
Then use mContext with Picasso:
Picasso.with(mContext).load("http://i.imgur.com/DvpvklR.png").into(thumbnail);

Please declare context variable like below and use it :
public class WishListAdapter extends RecyclerView.Adapter<WishListAdapter.DerpHolder> {
private List<WishListItem> listData;
private LayoutInflater inflater;
private Context context
public WishListAdapter(List<WishListItem> listData, Context c) {
inflater = LayoutInflater.from(c);
this.listData = listData;
this.context = c;
}
#Override
public WishListAdapter.DerpHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = inflater.inflate(R.layout.wish_list_item, parent, false);
return new DerpHolder(view);
}
#Override
public void onBindViewHolder(DerpHolder holder, int position) {
}
public void setListData(ArrayList<WishListItem> exerciseList) {
this.listData.clear();
this.listData.addAll(exerciseList);
}
#Override
public int getItemCount() {
return listData.size();
}
class DerpHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
ImageView thumbnail;
TextView title;
TextView subTitle;
View container;
public DerpHolder(View itemView) {
super(itemView);
thumbnail = itemView.findViewById(R.id.im_item_icon);
//subTitle = itemView.findViewById(R.id.lbl_item_sub_title);
//title = itemView.findViewById(R.id.lbl_item_text);
container = itemView.findViewById(R.id.cont_item_root);
container.setOnClickListener(this);
Picasso.with(context ).load("http://i.imgur.com/DvpvklR.png").into(thumbnail);
}
#Override
public void onClick(View v) {
Log.d("janitha", "item clicked");
}

Recycler View linear layout manager returning null

I have a recycler view which contains multiple items and each item in the recycler view contains a horizontal recycler view.The problem I am encountering is that the layout manager is null.
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference
This is my code so far.I have checked that the data I am receiving is intact.
RecipeAdapter ( The main adapter )
public class RecipeAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private Context context;
private List<Object> items;
private final int RECIPE = 0, JOKE = 1;
public RecipeAdapter(Context context) {
this.context = context;
this.items = new ArrayList<>();
}
public void setItems(List<Object> items) {
this.items = items;
}
public void add(Object object) {
items.add(object);
notifyItemInserted(items.size());
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
RecyclerView.ViewHolder viewHolder;
final LayoutInflater inflater = LayoutInflater.from(parent.getContext());
switch (viewType) {
case RECIPE:
View recipe = inflater.inflate(R.layout.item_recipe, parent, false);
viewHolder = new ViewHolder_Recipe(recipe);
break;
case JOKE:
View joke = inflater.inflate(R.layout.item_joke, parent, false);
viewHolder = new ViewHolder_Joke(joke);
break;
default:
View recipe_default = inflater.inflate(R.layout.item_recipe, parent, false);
viewHolder = new ViewHolder_Recipe(recipe_default);
break;
}
return viewHolder;
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
switch (holder.getItemViewType()) {
case RECIPE:
ViewHolder_Recipe viewHolderRecipe = (ViewHolder_Recipe) holder;
configureRecipeHolder(viewHolderRecipe, position);
break;
case JOKE:
ViewHolder_Joke viewHolderJoke = (ViewHolder_Joke) holder;
configureJokeHolder(viewHolderJoke, position);
break;
default:
ViewHolder_Recipe viewHolder_recipe_default = (ViewHolder_Recipe) holder;
configureRecipeHolder(viewHolder_recipe_default, position);
break;
}
}
private void configureJokeHolder(ViewHolder_Joke viewHolderJoke, int position) {
}
private void configureRecipeHolder(ViewHolder_Recipe viewHolderRecipe, int position) {
RecipeDetailed recipe = (RecipeDetailed) items.get(position);
Glide.with(context)
.load(recipe.getImage())
.into(viewHolderRecipe.getRecipe_image());
viewHolderRecipe.getRecipe_name().setText(recipe.getTitle());
viewHolderRecipe.getRecipe_prep().setText(recipe.getReadyInMinutes());
viewHolderRecipe.getRecipe_serves().setText(recipe.getServings());
viewHolderRecipe.getIngredientAdapter().setIngredients(recipe.getExtendedIngredients());
}
#Override
public int getItemViewType(int position) {
if (items.get(position) instanceof RecipeDetailed) {
return RECIPE;
} else if (items.get(position) instanceof Joke) {
return JOKE;
}
return super.getItemViewType(position);
}
#Override
public int getItemCount() {
return items.size();
}
}
The ViewHolder for that Adapter -- ViewHolder_Recipe
public class ViewHolder_Recipe extends RecyclerView.ViewHolder {
private CircularImageView recipe_image;
private TextView recipe_name;
private TextView recipe_prep;
private TextView recipe_serves;
private RecyclerView recyclerView;
private RecipeIngredientAdapter ingredientAdapter;
public ViewHolder_Recipe(View itemView) {
super(itemView);
recipe_image = (CircularImageView) itemView.findViewById(R.id.recipe_image);
recipe_name = (TextView) itemView.findViewById(R.id.recipe_name);
recipe_prep = (TextView) itemView.findViewById(R.id.recipe_prep);
recipe_serves = (TextView) itemView.findViewById(R.id.recipe_serves);
recyclerView = (RecyclerView) itemView.findViewById(R.id.recyclerView);
ingredientAdapter = new RecipeIngredientAdapter(itemView.getContext());
recyclerView.setLayoutManager(new LinearLayoutManager(itemView.getContext()
, LinearLayoutManager.HORIZONTAL, false));
recyclerView.setAdapter(ingredientAdapter);
}
public RecipeIngredientAdapter getIngredientAdapter() {
return ingredientAdapter;
}
public CircularImageView getRecipe_image() {
return recipe_image;
}
public TextView getRecipe_name() {
return recipe_name;
}
public TextView getRecipe_prep() {
return recipe_prep;
}
public TextView getRecipe_serves() {
return recipe_serves;
}
public RecyclerView getRecyclerView() {
return recyclerView;
}
}
The child adapter -- RecipeIngredientAdapter
public class RecipeIngredientAdapter extends RecyclerView.Adapter<ViewHolderRecipeIngredient> {
private Context context;
private ArrayList<Ingredient> ingredients;
public RecipeIngredientAdapter(Context context) {
this.context = context;
}
public void setIngredients(ArrayList<Ingredient> ingredients) {
this.ingredients = ingredients;
}
#Override
public ViewHolderRecipeIngredient onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
View view = inflater.inflate(R.layout.item_recipe_ingredients, parent, false);
return new ViewHolderRecipeIngredient(view);
}
#Override
public void onBindViewHolder(ViewHolderRecipeIngredient holder, int position) {
final Ingredient ingredient = ingredients.get(position);
Glide.with(context)
.load(ingredient.getImage())
.into(holder.getIngredient_image());
}
#Override
public int getItemCount() {
return 0;
}
}
The viewholder for that is a simple viewholder which contains an image.
I have seen posts online which seem to do the exact same thing and get it working,what exactly am i missing here?

From the error, it sounds like the RecyclerView is null, not the LayoutManager. Make sure you are using the proper id from the layout. are you sure the proper layout id of the RecyclerView is R.id.recyclerView?