I am rebuilding an old comic app, I would like to use View Binding instead of ButterKnife in my RecyclerView Adapter class? I am stumbling from it and can't get it trough. So if someone has an idea feel free to comment.
this is my class to fully understand what I have done:
package mowmow.adapter;
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.example.comic_app.R;
import com.squareup.picasso.Picasso;
import java.util.ArrayList;
import java.util.List;
import mowmow.database.aService;
import mowmow.database.dRetrofit;
import mowmow.model.TrendingResponse;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
public class adTrendingComic extends RecyclerView.Adapter<adTrendingComic.ViewHolder> {
#NonNull
#Override
public adTrendingComic.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.image_row, parent, false);
ButterKnife.bind(this, itemView);
return new ViewHolder(itemView);
}
#Override
public void onBindViewHolder(#NonNull adTrendingComic.ViewHolder holder, int position) {
getPosterPaths();
Picasso.get()
.load(posterPaths.get(position))
.placeholder(R.drawable.cloud_black_24dp).resize(350, 450)
.into(holder.trendingComicPosterIV);
}
private TrendingResponse trendingComicResponse;
private Context myContext;
private List<String> posterPaths = new ArrayList<>();
public adTrendingComic(TrendingResponse trendingComicResponse, Context context){
this.trendingComicResponse = trendingComicResponse;
this.myContext = context;
}
private void getPosterPaths(){
for(int i = 0; i < trendingComicResponse.getTop().size(); i++){
String posterUrlWithoutSize = trendingComicResponse
.getTop()
.get(i)
.getImageUrl()
.replace("/r/100x140", "");
posterPaths.add(posterUrlWithoutSize);
}
}
#Override
public int getItemCount() {
return trendingComicResponse.getTop().size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
#BindView(R.id.trendingPosterIV)
ImageView trendingComicPosterIV;
private Intent intent;
private aService service = dRetrofit.getData().create(aService.class);
private ViewHolder(View itemView) {
super(itemView);
ButterKnife.bind(this, itemView);
intent = new Intent(myContext, DetailsActivity.class);
trendingComicPosterIV.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int malId = trendingComicResponse.getTop().get(getAdapterPosition()).getMalId();
Call<ComicResponse> call = service.getComicByID(malId);
call.enqueue(new Callback<ComicResponse>() {
#Override
public void onResponse(#NonNull Call<ComicResponse> call, #NonNull Response<ComicResponse> response) {
if(response.body() != null) {
TempEnumForComics enumForComic = TempEnumForComics.INSTANCE;
enumForComic.setComic(response.body());
myContext.startActivity(intent);
}
else{
Toast.makeText(myContext, "No result", Toast.LENGTH_LONG).show();
}
}
#Override
public void onFailure(#NonNull Call<ComicResponse> call, #NonNull Throwable t) {
Toast.makeText(myContext, "No result", Toast.LENGTH_LONG).show();
}
});
}
});
}
}
}
Once again if there is someone who wants to help? it will be very much appreciated :)
Follow the documentation to setup the View Binding and than you'll have the binding classes generated. Here's how it should look like in your example:
#NonNull
#Override
public adTrendingComic.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
ImageRowBinding binding = ImageRowBinding.inflate(inflater, parent, false);
return new ViewHolder(binding);
}
And the view holder:
private ViewHolder(ImageRowBinding binding) {
super(binding.getRoot());
binding.getTrendingPosterIv().setOnClickListener(...);
[...]
}
Related
My scrolling list is displaying properly.
OnBindViewHolder is called for each item in initial display and when scrolling brings new items into view.
When I click on an item, I do see my ItemDetailsLookup and getItemDetails functions getting called, HOWEVER it doesn't call the OnBindViewHolder, and so setActivated isn't getting run.
The documentation for androidx.recyclerview.selection says "... When the user selects an item the library will record that in SelectionTracker then notify RecyclerView that the state of the item has changed. This will ultimately cause the value to be rebound by way of RecyclerView.Adapter#onBindViewHolder..." and I think I've done everything up to this point, but I must have missed something...
Any ideas?
Thanks
Here's my fragment:
package com.example.smartflashcards;
import android.content.Context;
import android.os.Bundle;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.selection.ItemDetailsLookup;
import androidx.recyclerview.selection.SelectionPredicates;
import androidx.recyclerview.selection.SelectionTracker;
import androidx.recyclerview.selection.StableIdKeyProvider;
import androidx.recyclerview.selection.StorageStrategy;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import java.io.File;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class StackSelectionFragment extends Fragment {
private static final String ARG_COLUMN_COUNT = "column-count";
private int mColumnCount = 1;
static SelectionTracker<Long> tracker;
public StackSelectionFragment() {
}
#SuppressWarnings("unused")
public static StackSelectionFragment newInstance(int columnCount) {
StackSelectionFragment fragment = new StackSelectionFragment();
Bundle args = new Bundle();
args.putInt(ARG_COLUMN_COUNT, columnCount);
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mColumnCount = getArguments().getInt(ARG_COLUMN_COUNT);
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_stack_selection_list, container, false);
File directory = getActivity().getFilesDir();
List<String> filesList = new ArrayList(Arrays.asList(directory.list()));
if (view instanceof RecyclerView) {
Context context = view.getContext();
RecyclerView recyclerView = (RecyclerView) view;
if (mColumnCount <= 1) {
recyclerView.setLayoutManager(new LinearLayoutManager(context));
} else {
recyclerView.setLayoutManager(new GridLayoutManager(context, mColumnCount));
}
recyclerView.setAdapter(new MyItemRecyclerViewAdapter(filesList));
recyclerView.getAdapter().hasStableIds();
this.tracker = new SelectionTracker.Builder<Long>(
"stack_selector",
recyclerView,
new StableIdKeyProvider(recyclerView),
new MyDetailsLookup(recyclerView),
StorageStrategy.createLongStorage()
).withSelectionPredicate(SelectionPredicates.<Long>createSelectAnything()).build();
}
return view;
}
final class MyDetailsLookup extends ItemDetailsLookup {
private final RecyclerView mRecyclerView;
MyDetailsLookup(RecyclerView recyclerView) {
mRecyclerView = recyclerView;
}
public #Nullable
ItemDetails getItemDetails(#NonNull MotionEvent e) {
View view = mRecyclerView.findChildViewUnder(e.getX(), e.getY());
if (view != null) {
RecyclerView.ViewHolder holder = mRecyclerView.getChildViewHolder(view);
if (holder instanceof MyItemRecyclerViewAdapter.ViewHolder) {
return ((MyItemRecyclerViewAdapter.ViewHolder)holder).getItemDetails();
}
}
return null;
}
}
}
Here's my adapter:
package com.example.smartflashcards;
import androidx.annotation.Nullable;
import androidx.recyclerview.selection.ItemDetailsLookup;
import androidx.recyclerview.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import android.widget.TextView;
import com.example.smartflashcards.databinding.FragmentStackSelectionBinding;
import java.util.List;
public class MyItemRecyclerViewAdapter extends RecyclerView.Adapter<MyItemRecyclerViewAdapter.ViewHolder> {
private final List<String> mValues;
public MyItemRecyclerViewAdapter(List<String> items) {
setHasStableIds(true);
mValues = items;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return new ViewHolder(FragmentStackSelectionBinding.inflate(LayoutInflater.from(parent.getContext()), parent, false));
}
#Override
public void onBindViewHolder(final ViewHolder holder, int position) {
holder.mItem = getItemId(position);
holder.mContentView.setText(mValues.get(position));
holder.mContentView.setActivated(StackSelectionFragment.tracker.isSelected((long) position));
}
#Override
public int getItemCount() {
return mValues.size();
}
#Override
public long getItemId(int position) {
return (long)position;
}
public class ViewHolder extends RecyclerView.ViewHolder {
public final TextView mIdView;
public final TextView mContentView;
public Long mItem;
public ViewHolder(FragmentStackSelectionBinding binding) {
super(binding.getRoot());
mIdView = binding.itemNumber;
mContentView = binding.content;
}
#Override
public String toString() {
return super.toString() + " '" + mContentView.getText() + "'";
}
public ItemDetailsLookup.ItemDetails<Long> getItemDetails() {
return new ItemDetailsLookup.ItemDetails<Long>() {
#Override
public int getPosition() {
return getAbsoluteAdapterPosition();
}
#Nullable
#Override
public Long getSelectionKey() {
return mItem;
}
};
}
}
}
By following the example at https://github.com/Thumar/recyclerview-selection/tree/master/app
I was able to get it working. See my working code below.
But I still don't know which of the changes made it work and why.
If anyone figures out what was causing my problem, please post a comment or answer.
Any and all other feedback is welcome as well.
THANKS
Here's my new fragment:
package com.example.smartflashcards;
import android.content.Context;
import android.os.Bundle;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.selection.ItemDetailsLookup;
import androidx.recyclerview.selection.Selection;
import androidx.recyclerview.selection.SelectionPredicates;
import androidx.recyclerview.selection.SelectionTracker;
import androidx.recyclerview.selection.StableIdKeyProvider;
import androidx.recyclerview.selection.StorageStrategy;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;
import java.io.File;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class StackSelectionFragment extends Fragment {
// TODO: Customize parameter argument names
private static final String ARG_COLUMN_COUNT = "column-count";
// TODO: Customize parameters
private int mColumnCount = 1;
SelectionTracker<Long> tracker; //TODO: add private?
private StackSelectionListener listener;
public interface StackSelectionListener {
public void onSelectStack(String stack);
}
String selections = "";
/**
* Mandatory empty constructor for the fragment manager to instantiate the
* fragment (e.g. upon screen orientation changes).
*/
public StackSelectionFragment() {
}
// TODO: Customize parameter initialization
#SuppressWarnings("unused")
public static StackSelectionFragment newInstance(int columnCount) {
StackSelectionFragment fragment = new StackSelectionFragment();
Bundle args = new Bundle();
args.putInt(ARG_COLUMN_COUNT, columnCount);
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mColumnCount = getArguments().getInt(ARG_COLUMN_COUNT);
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_stack_selection_list, container, false);
File directory = getActivity().getFilesDir();
List<String> filesList = new ArrayList(Arrays.asList(directory.list()));
// Set the adapter
if (view instanceof RecyclerView) {
Context context = view.getContext();
RecyclerView recyclerView = (RecyclerView) view;
if (mColumnCount <= 1) {
recyclerView.setLayoutManager(new LinearLayoutManager(context));
} else {
recyclerView.setLayoutManager(new GridLayoutManager(context, mColumnCount));
}
MyItemRecyclerViewAdapter adapter = new MyItemRecyclerViewAdapter(filesList);
recyclerView.setAdapter(adapter);
adapter.hasStableIds();
this.tracker = new SelectionTracker.Builder<Long>(
"stack_selector",
recyclerView,
new StableIdKeyProvider(recyclerView),
new MyDetailsLookup(recyclerView),
StorageStrategy.createLongStorage()
).withSelectionPredicate(SelectionPredicates.<Long>createSelectAnything()).build();
adapter.injectTracker(this.tracker);
SelectionTracker.SelectionObserver<Long> observer = new SelectionTracker.SelectionObserver<Long>() {
#Override
public void onSelectionChanged() {
super.onSelectionChanged();
//TODO: replace this placeholder action with something useful
selections = "";
tracker.getSelection().forEach(item -> selections += adapter.getContent(item.intValue()));//selections += item);
//listener.onSelectStack("selections"); //This causes an error???
Context context = getContext();
Toast toast = Toast.makeText(context, selections, Toast.LENGTH_LONG);
toast.show();
}
};
this.tracker.addObserver(observer);
}
return view;
}
final class MyDetailsLookup extends ItemDetailsLookup {
private final RecyclerView mRecyclerView;
MyDetailsLookup(RecyclerView recyclerView) {
mRecyclerView = recyclerView;
}
public #Nullable
ItemDetails getItemDetails(#NonNull MotionEvent e) {
View view = mRecyclerView.findChildViewUnder(e.getX(), e.getY());
if (view != null) {
RecyclerView.ViewHolder holder = mRecyclerView.getChildViewHolder(view);
if (holder instanceof MyItemRecyclerViewAdapter.ViewHolder) {
return ((MyItemRecyclerViewAdapter.ViewHolder)holder).getItemDetails();
}
}
return null;
}
}
Here's my new adapter:
package com.example.smartflashcards;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.recyclerview.selection.ItemDetailsLookup;
import androidx.recyclerview.selection.SelectionTracker;
import androidx.recyclerview.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.List;
public class MyItemRecyclerViewAdapter extends RecyclerView.Adapter<MyItemRecyclerViewAdapter.ViewHolder> {
private final List<String> mValues;
private SelectionTracker<Long> selectionTracker;
public MyItemRecyclerViewAdapter(List<String> items) {
setHasStableIds(true); //TODO: remove redundancy between this and "recyclerView.getAdapter().hasStableIds()" in the Fragment
mValues = items;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.fragment_stack_selection, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
String item = this.mValues.get(position);
holder.bind(item, selectionTracker.isSelected((long) position));
}
#Override
public int getItemCount() {
return mValues.size();
}
#Override
public long getItemId(int position) {
return (long)position;
}
public String getContent(int position) {
return mValues.get(position);
}
public void injectTracker(SelectionTracker<Long> tracker)
{
this.selectionTracker = tracker;
}
public class ViewHolder extends RecyclerView.ViewHolder {
public final TextView mContentView;
public ViewHolder(#NonNull View itemView) {
super(itemView);
mContentView = itemView.findViewById(R.id.content);
}
#Override
public String toString() {
return super.toString() + " '" + mContentView.getText() + "'";
}
public void bind(String item, Boolean activate) {
this.mContentView.setText(item);
itemView.setActivated(activate); //TODO: understand how "itemView" exists outside of the constructor
}
public ItemDetailsLookup.ItemDetails<Long> getItemDetails() {
return new ItemDetailsLookup.ItemDetails<Long>() {
#Override
public int getPosition() {
return getAbsoluteAdapterPosition();
}
#Nullable
#Override
public Long getSelectionKey() {
return (long) getAbsoluteAdapterPosition();
}
};
}
}
}
I am new, and I am making an app that displays data in a cardView within a recyclerView in android studio. I am trying to be able to delete the data that is displayed on the cardView. The cardView and data gets deleted as it should, but once I go back to the activity holding the cardView and recyclerView, it's all still there. Does anyone know why this is happening? I'll post my code below
ReminderDBHelper:
package com.example.lasttry;
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.MyViewHolder> {
private Context context;
private ArrayList reminder_id, reminder_title, reminder_location, reminder_medication;
reminderDBHelper mydb;
Button reminderDelete;
CustomAdapter(Context context,
ArrayList reminder_id,
ArrayList reminder_title,
ArrayList reminder_location,
ArrayList reminder_medication) {
this.context = context;
this.reminder_id = reminder_id;
this.reminder_title = reminder_title;
this.reminder_location = reminder_location;
this.reminder_medication = reminder_medication;
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(R.layout.my_row, parent, false);
return new MyViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull MyViewHolder holder, final int position) {
holder.reminder_id.setText(String.valueOf(reminder_id.get(position)));
holder.reminder_title.setText(String.valueOf(reminder_title.get(position)));
holder.reminder_location.setText(String.valueOf(reminder_location.get(position)));
holder.reminder_medication.setText(String.valueOf(reminder_medication.get(position)));
holder.reminderDelete.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
mydb = new reminderDBHelper(context);
String id = String.valueOf(reminder_id);
mydb.deleteData(id);
reminder_id.remove(holder.getAdapterPosition());
notifyItemRemoved(holder.getLayoutPosition());
}
});
holder.mainLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(context, UpdateActivity.class);
intent.putExtra("id", String.valueOf(reminder_id.get(holder.getAdapterPosition())));
intent.putExtra("title", String.valueOf(reminder_title.get(holder.getAdapterPosition())));
intent.putExtra("location", String.valueOf(reminder_location.get(holder.getAdapterPosition())));
intent.putExtra("medication", String.valueOf(reminder_medication.get(holder.getAdapterPosition())));
context.startActivity(intent);
}
});
}
#Override
public int getItemCount() {
return reminder_id.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
TextView reminder_id, reminder_title, reminder_location, reminder_medication;
Button reminderDelete;
LinearLayout mainLayout;
public MyViewHolder(#NonNull View itemView) {
super(itemView);
reminderDelete = itemView.findViewById(R.id.reminder_delete);
reminder_id = itemView.findViewById(R.id.reminder_id);
reminder_title = itemView.findViewById(R.id.reminder_title);
reminder_location = itemView.findViewById(R.id.reminder_location);
reminder_medication = itemView.findViewById(R.id.reminder_medication);
mainLayout = itemView.findViewById(R.id.mainLayout);
}
}
}
CustomAdapter:
package com.example.lasttry;
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.MyViewHolder> {
private Context context;
private ArrayList reminder_id, reminder_title, reminder_location, reminder_medication;
reminderDBHelper mydb;
Button reminderDelete;
CustomAdapter(Context context,
ArrayList reminder_id,
ArrayList reminder_title,
ArrayList reminder_location,
ArrayList reminder_medication) {
this.context = context;
this.reminder_id = reminder_id;
this.reminder_title = reminder_title;
this.reminder_location = reminder_location;
this.reminder_medication = reminder_medication;
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(R.layout.my_row, parent, false);
return new MyViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull MyViewHolder holder, final int position) {
holder.reminder_id.setText(String.valueOf(reminder_id.get(position)));
holder.reminder_title.setText(String.valueOf(reminder_title.get(position)));
holder.reminder_location.setText(String.valueOf(reminder_location.get(position)));
holder.reminder_medication.setText(String.valueOf(reminder_medication.get(position)));
holder.reminderDelete.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
mydb = new reminderDBHelper(context);
String id = String.valueOf(reminder_id);
mydb.deleteData(id);
reminder_id.remove(holder.getAdapterPosition());
notifyItemRemoved(holder.getLayoutPosition());
}
});
holder.mainLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(context, UpdateActivity.class);
intent.putExtra("id", String.valueOf(reminder_id.get(holder.getAdapterPosition())));
intent.putExtra("title", String.valueOf(reminder_title.get(holder.getAdapterPosition())));
intent.putExtra("location", String.valueOf(reminder_location.get(holder.getAdapterPosition())));
intent.putExtra("medication", String.valueOf(reminder_medication.get(holder.getAdapterPosition())));
context.startActivity(intent);
}
});
}
#Override
public int getItemCount() {
return reminder_id.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
TextView reminder_id, reminder_title, reminder_location, reminder_medication;
Button reminderDelete;
LinearLayout mainLayout;
public MyViewHolder(#NonNull View itemView) {
super(itemView);
reminderDelete = itemView.findViewById(R.id.reminder_delete);
reminder_id = itemView.findViewById(R.id.reminder_id);
reminder_title = itemView.findViewById(R.id.reminder_title);
reminder_location = itemView.findViewById(R.id.reminder_location);
reminder_medication = itemView.findViewById(R.id.reminder_medication);
mainLayout = itemView.findViewById(R.id.mainLayout);
}
}
}
I have searched stackOverflow and reddit, but nothing seems to work. I have tried making the array array list instead.
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 1 year ago.
I have build a RecyclerViewer application in Java using android studio.
When I run the app it crashes, when I checked the Logcat I found there is a null pointer exception in my Adapter.
onBindViewHolder method.
This covers line 49.
#Override
public void onBindViewHolder(#NonNull ContactsAdapter.ViewHolder holder, int position) {
holder.txtName.setText(contacts.get(position).getName());
holder.txtName.setText(contacts.get(position).getEmail());
Glide.with(context).asBitmap().load(contacts.get(position).getImage()).into(holder.image);
holder.parent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(context, contacts.get(position).getName() + " Clicked", Toast.LENGTH_SHORT).show();
}
});
}
Logcat log
java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.cardview.widget.CardView.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.example.learningapplication.ContactsAdapter.onBindViewHolder(ContactsAdapter.java:49)
at com.example.learningapplication.ContactsAdapter.onBindViewHolder(ContactsAdapter.java:19)
EDIT:
Here is the full code:
package com.example.learningapplication;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.cardview.widget.CardView;
import androidx.recyclerview.widget.RecyclerView;
import com.bumptech.glide.Glide;
import java.util.ArrayList;
public class ContactsAdapter extends RecyclerView.Adapter<ContactsAdapter.ViewHolder>{
private Context context;
ArrayList<Contacts> contacts = new ArrayList<>();
public void setContacts(ArrayList<Contacts> contacts) {
this.contacts = contacts;
notifyDataSetChanged();
}
public ContactsAdapter(Context context) {
this.context = context;
}
public ContactsAdapter() {
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.contacts_layout, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull ContactsAdapter.ViewHolder holder, int position) {
holder.txtName.setText(contacts.get(position).getName());
holder.txtName.setText(contacts.get(position).getEmail());
Glide.with(context).asBitmap().load(contacts.get(position).getImage()).into(holder.image);
holder.parent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(context, contacts.get(position).getName() + " Clicked", Toast.LENGTH_SHORT).show();
}
});
}
#Override
public int getItemCount() {
return contacts.size();
}
public static class ViewHolder extends RecyclerView.ViewHolder{
private TextView txtName;
private TextView txtEmail;
private ImageView image;
private CardView parent;
public ViewHolder(#NonNull View itemView) {
super(itemView);
txtName = itemView.findViewById(R.id.txtName);
txtEmail = itemView.findViewById(R.id.txtEmail);
image = itemView.findViewById(R.id.image);
}
}
}
``
as i understand:
holder.parent - this is null
check your initializations
I want the app to open a page when the user taps on an item and pass some extra information to that intent. That's it. I tried about 7 - 10 onclickListener types but I didn't solve anything. I am posting my adapter class with the latest implementation ( that doesn't work ). Json works and the Recyclerview loads data and images from url with no problems.
package byDragosT.myapplication;
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.GridLayout;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.constraintlayout.widget.ConstraintLayout;
import androidx.recyclerview.widget.RecyclerView;
import com.squareup.picasso.Picasso;
import java.util.ArrayList;
public class RecipeApiAdapter extends RecyclerView.Adapter<RecipeApiAdapter.RecipeViewHolder> {
private ArrayList<RecipeItem> recipeItems;
private Context context;
public RecipeApiAdapter(ArrayList<RecipeItem> recipeItems, Context context){
this.recipeItems = recipeItems;
this.context = context;
}
#NonNull
#Override //// Mare grija ce layout pui aici - sfat pentru viitor - mi-a luat 4 ore sa gasesc eroarea
public RecipeViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.recipe_item_in_recyclerview_api, parent, false);
return new RecipeViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull RecipeViewHolder holder, int position) {
final RecipeItem recipeItem = recipeItems.get(position);
holder.title.setText(recipeItem.getMnameRecipe());
holder.description.setText(recipeItem.getMdescribeRecipe());
Picasso.get().load(recipeItem.getItemPictureUrl())
.into(holder.jpegRecipe);
System.out.println("image with title: " + holder.title.getText() + "was added in theory");
}
#Override
public int getItemCount() {
return recipeItems.size();
}
public static class RecipeViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public ImageView jpegRecipe;
public TextView title;
public TextView description;
public RelativeLayout containerView;
public RecyclerView mRecyclerView;
RecipeViewHolder(View view){
super(view);
jpegRecipe = view.findViewById(R.id.picture);
title = view.findViewById(R.id.recipe_name);
description = view.findViewById(R.id.ingredients_list);
containerView = view.findViewById(R.id.recipe_item_container); // vezi aici
mRecyclerView = view.findViewById(R.id.recyclerView);
}
#Override
public void onClick(View v) {
int itemPosition = mRecyclerView.getChildLayoutPosition(v);
RecipeItem current = recipeItems.get(itemPosition);
Intent intent = new Intent(v.getContext(), RecipeDetailsActivity.class);
intent.putExtra("name", current.getMnameRecipe());
v.getContext().startActivity(intent);
}
}
}
Try adding view.setOnClickListener(this);
RecipeViewHolder(View view){
super(view);
view.setOnClickListener(this);
.....
}
Hello Every One I am trying to move from one activity to another using intent in adaptor class of recycler view but I am getting son=me errors in doing so, Following are the errors:
1.PakistaniActivity is not a Enclosing class.
2.Cannot resolve method StatrActivity();
Here is my code:
PakistaniActivity.Java
package com.recycler.hp.navigationbar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
public class PakistaniActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pakistani);
RecyclerView rl=findViewById(R.id.list);
rl.setLayoutManager(new LinearLayoutManager(this));
String[] languges={"Badnamiyan", "song2","song3","song4","Song5","song6","song7","song8","song9"};
rl.setAdapter(new Adaptor(languges));
}
}
Adaptor.java
package com.recycler.hp.navigationbar;
import android.content.Intent;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import java.io.IOException;
import java.net.URL;
public class Adaptor extends RecyclerView.Adapter<Adaptor.viewholder> {
private String[] data;
public Adaptor(String[] data) {
this.data = data;
}
#Override
public viewholder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
View view = inflater.inflate(R.layout.list_item1, parent, false);
return new viewholder(view);
}
#Override
public void onBindViewHolder(viewholder holder, final int position) {
String title = data[position];
holder.t.setText(title);
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
long x;
x=getItemId(position);
if(x==0)
{
Intent intent=new Intent(PakistaniActivity.this,Revival_Activity.class);
startActivity(intent);
}
}
});
}
#Override
public int getItemCount() {
return data.length;
}
public class viewholder extends RecyclerView.ViewHolder {
ImageView i;
TextView t;
public viewholder(View itemView) {
super(itemView);
i = itemView.findViewById(R.id.img1);
t = itemView.findViewById(R.id.main1);
}
}
}
Try not starting activities inside the adapter. You can use this adapter:
public abstract class ClickableAdapter<VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> {
private ClickItemListener clickItemListener;
public void setClickItemListener(ClickItemListener clickItemListener) {
this.clickItemListener = clickItemListener;
}
#Override
public void onBindViewHolder(#NonNull final VH holder, int position) {
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (clickItemListener != null)
clickItemListener.onClickItem(holder.itemView, holder.getAdapterPosition());
else
throw new IllegalStateException("Click listener not set");
}
});
}
public interface ClickItemListener {
void onClickItem(View v, int position);
}
}
Then make your adapter extend mine:
public class Adaptor extends ClickableAdapter<Adaptor.viewholder> {
private String[] data;
public Adaptor(String[] data) {
this.data = data;
}
#Override
public viewholder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
View view = inflater.inflate(R.layout.list_item1, parent, false);
return new viewholder(view);
}
#Override
public void onBindViewHolder(viewholder holder, final int position) {
super.onBindViewHolder(holder,position);
String title = data[position];
holder.t.setText(title);
}
#Override
public int getItemCount() {
return data.length;
}
public class viewholder extends RecyclerView.ViewHolder {
ImageView i;
TextView t;
public viewholder(View itemView) {
super(itemView);
i = itemView.findViewById(R.id.img1);
t = itemView.findViewById(R.id.main1);
}
}
}
Finally in your activity you can set the behaviour for the adapter:
Adaptor adapter = new Adaptor(languges)
rl.setAdapter(adapter);
adapter.setClickItemListener(new ClickableAdapter.ClickItemListener() {
#Override
public void onClickItem(View v, int position) {
if(position==0)
{
Intent intent=new Intent(PakistaniActivity.this,Revival_Activity.class);
startActivity(intent);
}
}
});
Write
Intent intent=new Intent(getContext(),Revival_Activity.class);
startActivity(intent);
instead of this
Intent intent=new Intent(PakistaniActivity.this,Revival_Activity.class);
startActivity(intent);
or
pass the context from the from PakistaniActivity to the Adapter class and user the context as the data member of the adapter class
Pass the context of PakistaniActivity into Adapter
new Adaptor(languges,getApplicationContext);
private Context context;
public Adaptor(String[] data,Conetext context) {
this.data = data;
this.context = conetext;
}
Intent intent=new Intent(context,Revival_Activity.class);
startActivity(intent);
Try using this:
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
long x;
x=getItemId(position);
if(x==0){
Intent intent = new Intent(getContext(), Revival_Activity.class);
context.startActivity(intent);