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Retrieve array of images from firestore and show them in recycler view

I'm trying to retrieve array of images from firestore. I uploaded the images to firebase storage and have added the url to firestore. I can see the card of images in the recycler view but the images are not visible. In Logcat, I get the links of the images which redirect to the images saved in firebase storage. I have attached the adapter class.
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageButton;
import android.widget.ImageView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.bumptech.glide.Glide;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
public class imageAdapter extends RecyclerView.Adapter<imageAdapter.holder>
{
ArrayList<String> imageUrl;
public imageAdapter(ArrayList<String> imageUrl)
{
this.imageUrl = imageUrl;
}
#NonNull
#Override
public holder onCreateViewHolder(#NonNull ViewGroup parent, int viewType)
{
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.activity_image_item,parent,false);
return new holder(v).linkAdapter(this) ;
}
#Override
public void onBindViewHolder(#NonNull holder holder, int position)
{
Glide.with(holder.imageView.getContext()).load(imageUrl).into(holder.imageView);
}
#Override
public int getItemCount()
{
return imageUrl.size();
}
class holder extends RecyclerView.ViewHolder
{
ImageButton imageButton;
ImageView imageView;
private imageAdapter imageAdapter;
public holder(#NonNull View itemView)
{
super(itemView);
imageButton=itemView.findViewById(R.id.imageBtn);
imageView=itemView.findViewById(R.id.imageView);
imageButton.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
imageAdapter.imageUrl.remove(getAdapterPosition());
imageAdapter.notifyItemRemoved(getAdapterPosition());
}
});
}
public holder linkAdapter(imageAdapter imageAdapter)
{
this.imageAdapter = imageAdapter;
return this;
}
}
}
MainActivity.java
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.activity.result.ActivityResult;
import androidx.activity.result.ActivityResultCallback;
import androidx.activity.result.ActivityResultLauncher;
import androidx.activity.result.contract.ActivityResultContracts;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import com.darsh.multipleimageselect.activities.AlbumSelectActivity;
import com.darsh.multipleimageselect.helpers.Constants;
import com.firebase.ui.firestore.FirestoreRecyclerOptions;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.material.button.MaterialButton;
import com.google.firebase.firestore.DocumentSnapshot;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.Query;
import com.marquedo.marquedo.ui.Prod_n_Cat.Product.AboutModelClass;
import com.marquedo.marquedo.ui.Prod_n_Cat.Product.ProductListAdapter1;
import com.marquedo.marquedo.ui.Prod_n_Cat.Product.ProductModelClass;
import java.util.ArrayList;
import java.util.List;
public class update_product extends AppCompatActivity
{
private String position;
private FirebaseFirestore db = FirebaseFirestore.getInstance();
private EditText category, name, details;
private RecyclerView recyclerView;
private AboutModelClass aboutModelClass;
private MaterialButton add_images_button;
private imageAdapter imageAdapter;
private ActivityResultLauncher<Intent> getResult;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_update_product);
Intent preview = new Intent(this, preview_product.class);
Button preview_prod = findViewById(R.id.show_preview);
preview_prod.setOnClickListener(view ->
{
startActivity(preview);
});
category = findViewById(R.id.prodCategory);
name = findViewById(R.id.productName);
details = findViewById(R.id.prodDetails);
LinearLayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(null);
Bundle intent = getIntent().getExtras();
position = intent.get("key").toString();
//Getting data from firestore and displaying it on the fields
db.collection("Store").document("TFTVHvZaHOIxjYLnHvwc").collection("products").document(position).collection("about").document("product_id").get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
#Override
public void onSuccess(#NonNull DocumentSnapshot documentSnapshot)
{
aboutModelClass = documentSnapshot.toObject(AboutModelClass.class);
String Category = aboutModelClass.getCategory();
String Name = aboutModelClass.getName();
String Details = aboutModelClass.getDetails();
ArrayList<String> Urls = (ArrayList<String>) documentSnapshot.get("Images");
Log.i("showlist", Urls.toString());
imageAdapter = new imageAdapter(Urls);
recyclerView.setAdapter(imageAdapter2);
category.setText(Category);
name.setText(Name);
details.setText(Details);
}
});
}
}
ModelClass.java
import java.util.List;
public class AboutModelClass
{
String Category, Details, Name;
List<String> urls;
public AboutModelClass()
{
}
public AboutModelClass(String category, String details, String name, List<String> urls) {
Category = category;
Details = details;
Name = name;
this.urls = urls;
}
public String getCategory() {
return Category;
}
public void setCategory(String category) {
Category = category;
}
public String getDetails() {
return Details;
}
public void setDetails(String details) {
Details = details;
}
public String getName() {
return Name;
}
public void setName(String name) {
Name = name;
}
public List<String> getUrls() {
return urls;
}
public void setUrls(List<String> urls) {
this.urls = urls;
}
}

No setter/field for url found on class com.example.scheduletask.model.Task can't retrieve data from firebase database to detail activity

im trying to retrieve data from firebase to detail activity. On the listview, it show perfectly. But when i click, the detail activity opened but still empty. All it says "W/ClassMapper: No setter/field for url found on class com.example.scheduletask.model.Task". I thought the setter on model task wasn't used, but i don't know... im sorry, i don't understand, i don't know what i missed:( any help is appreciated, thank youuu
TaskActivity.java
package com.example.scheduletask;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import com.example.scheduletask.adapter.MatkulAdapter;
import com.example.scheduletask.adapter.TaskAdapter;
import com.example.scheduletask.adapter.TaskDetailAdapter;
import com.example.scheduletask.database.FirebaseTaskHelper;
import com.example.scheduletask.model.Matkul;
import com.example.scheduletask.model.Task;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import java.util.ArrayList;
import java.util.Iterator;
public class TaskActivity extends AppCompatActivity {
DatabaseReference databaseReference;
ListView listViewTask;
FloatingActionButton fabAddTask;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_task);
databaseReference = FirebaseDatabase.getInstance().getReference("Task");
listViewTask = findViewById(R.id.tasklist);
showData();
fabAddTask = findViewById(R.id.fab_addtask);
fabAddTask.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(TaskActivity.this, CreateTaskActivity.class);
startActivity(intent);
}
});
listViewTask.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String subjectTask = ((TextView)view.findViewById(R.id.txt_subjectlisttask)).getTag().toString();
Intent taskDetail = new Intent(TaskActivity.this, TaskDetailActivity.class);
taskDetail.putExtra("subjectTask", subjectTask);
startActivity(taskDetail);
}
});
}
private void showData() {
final ArrayList<String> subjectTask = new ArrayList<>();
final ArrayList<String> taskDueDate = new ArrayList<>();
final ArrayList<String> taskDescription = new ArrayList<>();
final ArrayList<String> imageURL = new ArrayList<>();
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
Iterable<DataSnapshot> snapshotIterable = dataSnapshot.getChildren();
Iterator<DataSnapshot> iterator = snapshotIterable.iterator();
while (iterator.hasNext()){
Task value = iterator.next().getValue(Task.class);
assert value != null;
subjectTask.add(value.getSubjectTask());
taskDescription.add(value.getTaskDescription());
taskDueDate.add(value.getTaskDueDate());
imageURL.add(value.getImageURL());
((TaskAdapter)listViewTask.getAdapter()).notifyDataSetChanged();
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
listViewTask.setAdapter(new TaskAdapter(subjectTask, taskDescription, taskDueDate, imageURL, this));
}
#Override
protected void onResume() {
super.onResume();
showData();
}
}
Task.java (this is the model)
package com.example.scheduletask.model;
public class Task {
private String taskDueDate;
public String getTaskDueDate() {
return taskDueDate;
}
public void setTaskDueDate(String taskDueDate) {
this.taskDueDate = taskDueDate;
}
private String subjectTask;
public String getTaskDescription() {
return taskDescription;
}
public void setTaskDescription(String taskDescription) {
this.taskDescription = taskDescription;
}
public String getImageURL() {
return imageURL;
}
public void setImageURL(String imageURL) {
this.imageURL = imageURL;
}
private String taskDescription;
private String imageURL;
public String getSubjectTask() {
return subjectTask;
}
public void setSubjectTask(String subjectTask) {
this.subjectTask = subjectTask;
}
}
TaskDetailActivity.java
package com.example.scheduletask;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;
import com.example.scheduletask.model.Task;
import com.github.barteksc.pdfviewer.PDFView;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;
import com.google.firebase.database.ValueEventListener;
import com.google.firebase.storage.FirebaseStorage;
import com.google.firebase.storage.StorageReference;
import com.squareup.picasso.Picasso;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Map;
public class TaskDetailActivity extends AppCompatActivity {
EditText edtSubject, edtDueDate, edtDescription;
ImageView filePhoto;
ProgressBar progressBarDetail;
Button btnEdit, btnDelete;
DatabaseReference databaseReference;
private String photoURL, subjectTask;
Button btnViewPDF;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_task_detail);
databaseReference = FirebaseDatabase.getInstance().getReference("Task");
subjectTask = getIntent().getExtras().getString("subjectTask");
progressBarDetail = findViewById(R.id.progressbardetail);
progressBarDetail.setVisibility(View.INVISIBLE);
readData();
findAllViewsID();
}
private void readData() {
progressBarDetail.setVisibility(View.VISIBLE);
Query findQuery = databaseReference.orderByKey().equalTo(subjectTask);
findQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot getSnapshot : dataSnapshot.getChildren()){
edtSubject.setText(getSnapshot.child("subjectTask").getValue().toString());
edtDescription.setText(getSnapshot.child("taskDescription").getValue().toString());
edtDueDate.setText(getSnapshot.child("taskDueDate").getValue().toString());
photoURL = getSnapshot.child("imageURL").getValue().toString();
Picasso.get().load(photoURL).fit().into(filePhoto);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
progressBarDetail.setVisibility(View.INVISIBLE);
}
});
progressBarDetail.setVisibility(View.INVISIBLE);
}
private void findAllViewsID() {
edtSubject = findViewById(R.id.edt_updatetasksubject);
edtDescription = findViewById(R.id.edt_updatetaskdescription);
edtDueDate = findViewById(R.id.edt_updateduedatetime);
filePhoto = findViewById(R.id.iv_taskphotoinput);
btnViewPDF = findViewById(R.id.btn_viewpdf);
btnDelete = findViewById(R.id.btn_deletetask);
btnEdit = findViewById(R.id.btn_edittask);
}
}
TaskAdapter.java
package com.example.scheduletask.adapter;
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import com.example.scheduletask.R;
import com.example.scheduletask.TaskActivity;
import com.example.scheduletask.TaskDetailActivity;
import com.example.scheduletask.model.Task;
import com.squareup.picasso.Picasso;
import java.util.ArrayList;
public class TaskAdapter extends BaseAdapter {
private ArrayList<String> subjectTask;
private ArrayList<String> taskDescription;
private ArrayList<String> taskDueDate;
private ArrayList<String> imageURL;
private AppCompatActivity activity;
public TaskAdapter(ArrayList<String> subjectTask, ArrayList<String> taskDescription, ArrayList<String> taskDueDate, ArrayList<String> imageURL, AppCompatActivity activity) {
this.subjectTask = subjectTask;
this.taskDescription = taskDescription;
this.taskDueDate = taskDueDate;
this.imageURL = imageURL;
this.activity = activity;
}
Context ctx;
ArrayList<Task> tasks;
#Override
public int getCount() {
return subjectTask.size();
}
#Override
public Object getItem(int position) {
return subjectTask.get(position);
}
#Override
public long getItemId(int position) {
return 0;
}
public TaskAdapter(#NonNull Context ctx, ArrayList<Task> tasks) {
this.ctx = ctx;
this.tasks = tasks;
}
public View getView(int position, View view, ViewGroup parent) {
view = LayoutInflater.from(activity.getApplicationContext())
.inflate(R.layout.list_task, parent, false);
view.findViewById(R.id.txt_subjectlisttask).setTag(String.valueOf(subjectTask.get(position)));
((TextView)view.findViewById(R.id.txt_subjectlisttask)).setText(String.valueOf(subjectTask.get(position)));
((TextView)view.findViewById(R.id.txt_duedatetasklist)).setText(String.valueOf(taskDueDate.get(position)));
return view; }
}
Here is the logcat when i click the task listview
And this is my database

Store data in 'REALM DATABASE' and show in a recyclerview

I want to store my data in realm database, then retrieve and show it in a recyclerview. All my code is correct in my point of view but it gives me an error about null pointer exception. Despite my efforts I was unable to solve it.
Main Activty Class
package com.deitel.realmrecyclerviewspinnerpriority;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.database.Cursor;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import com.deitel.realmrecyclerviewspinnerpriority.Adapter.AdapterClass;
import com.deitel.realmrecyclerviewspinnerpriority.Database.RelmHelper;
import com.deitel.realmrecyclerviewspinnerpriority.Modelclass.ModelClass;
import java.util.ArrayList;
import io.realm.Realm;
import io.realm.RealmConfiguration;
import io.realm.RealmResults;
public class MainActivity extends AppCompatActivity {
private static final String TAG="MainActivity";
Realm realm;
EditText text_name;
EditText text_details;
ImageButton btn_ascending,btn_descending;
RecyclerView rv;
Spinner spinner;
TextView text_data;
Button btn_save,btn_view;
ArrayList<String> itemslist;
AdapterClass addapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text_name = findViewById(R.id.text_name);
text_details = findViewById(R.id.text_details);
text_data=findViewById(R.id.text_data);
btn_save=findViewById(R.id.btn_show);
btn_view=findViewById(R.id.btn_view);
btn_save = findViewById(R.id.btn_show);
rv = findViewById(R.id.recyclerview);
btn_ascending=findViewById(R.id.btn_ascending);
btn_descending=findViewById(R.id.btn_descneding);
rv.setLayoutManager(new LinearLayoutManager(getApplicationContext()));
final RelmHelper helper=new RelmHelper(realm);
itemslist=helper.retrievedata();
addapter = new AdapterClass(MainActivity.this,itemslist);
rv.setAdapter(addapter);
spinner = findViewById(R.id.spinner);
final ArrayList<Integer> arrayList = new ArrayList<>();
arrayList.add(1);
arrayList.add(2);
arrayList.add(3);
arrayList.add(4);
arrayList.add(5);
arrayList.add(6);
arrayList.add(7);
arrayList.add(8);
arrayList.add(9);
arrayList.add(10);
arrayList.add(11);
arrayList.add(12);
arrayList.add(13);
final ArrayAdapter<Integer> adapter = new ArrayAdapter<Integer>(this, android.R.layout.simple_spinner_item, arrayList);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
btn_save.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
ModelClass md=new ModelClass();
md.setName(text_name.getText().toString());
md.setDetails(text_details.getText().toString());
/*save data*/
RelmHelper helper=new RelmHelper(realm);
helper.savedata(md);
}
});
}
}
```
MY REALM HELPER CLASS
```
package com.deitel.realmrecyclerviewspinnerpriority.Database;
import android.view.Display;
import com.deitel.realmrecyclerviewspinnerpriority.Modelclass.ModelClass;
import java.util.ArrayList;
import io.realm.Realm;
import io.realm.RealmResults;
public class RelmHelper {
Realm realm;
public RelmHelper(Realm realm) {
this.realm = realm;
}
public void savedata(final ModelClass modelClass){
realm.executeTransactionAsync(new Realm.Transaction() {
#Override
public void execute(Realm realm) {
ModelClass md=realm.copyToRealm(modelClass);
}
});
}
public ArrayList<String> retrievedata(){
ArrayList<String> modelclassdata=new ArrayList<>();
RealmResults<ModelClass> modelClass=realm.where(ModelClass.class).findAll();
for (ModelClass MD:modelClass){
modelclassdata.add(MD.getName());
modelclassdata.add(MD.getDetails());
// modelclassdata.add(MD.getPriority());
}
return modelclassdata;
}
}
```
Model Class
```
package com.deitel.realmrecyclerviewspinnerpriority.Modelclass;
import io.realm.RealmObject;
public class ModelClass extends RealmObject {
private String name;
private String details;
// private int priority;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDetails() {
return details;
}
public void setDetails(String details) {
this.details = details;
}
// public int getPriority() {
// return priority;
// }
//
// public void setPriority(int priority) {
// this.priority = priority;
// }
}
```
Adapter Class
```[![enter image description here][1]][1]
package com.deitel.realmrecyclerviewspinnerpriority.Adapter;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageButton;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.deitel.realmrecyclerviewspinnerpriority.Modelclass.ModelClass;
import com.deitel.realmrecyclerviewspinnerpriority.R;
import java.util.ArrayList;
import java.util.List;
public class AdapterClass extends RecyclerView.Adapter<AdapterClass.Viewholder> {
ArrayList<String> modelClassList;
Context context;
public AdapterClass(#NonNull Context context,ArrayList<String> modelClassList){
this.modelClassList=modelClassList;
this.context=context;
}
#NonNull
#Override
public AdapterClass.Viewholder onCreateViewHolder(#NonNull ViewGroup viewGroup, int viewType) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.custom_cardview_layout, viewGroup, false);
Viewholder holder = new Viewholder(view);
return holder;
}
#Override
public void onBindViewHolder(#NonNull AdapterClass.Viewholder holder, final int position) {
holder.textView_name.setText("Name :" + modelClassList.get(position));
holder.textView_details.setText("Details : " + modelClassList.get(position));
// holder.textView_priority.setText("Priority : " + modelClassList.get(position));
// holder.btn_delete.setOnClickListener(new View.OnClickListener() {
// #Override
// public void onClick(View v) {
// modelClassList.remove(position);
// notifyItemRemoved(position);
// notifyItemRangeChanged(position,modelClassList.size());
// notifyDataSetChanged();
// }
// });
}
#Override
public int getItemCount() {
return modelClassList.size();
}
public class Viewholder extends RecyclerView.ViewHolder {
TextView textView_name;
TextView textView_details;
TextView textView_priority;
ImageButton btn_delete;
public Viewholder(#NonNull View view) {
super(view);
textView_name = view.findViewById(R.id.textview_name);
textView_details = view.findViewById(R.id.textview_details);
textView_priority = view.findViewById(R.id.textview_priotity);
btn_delete=view.findViewById(R.id.btn_delete);
}
}
}

Custom Dialog in Nested Recyclerview

I have implemented a expandable nested RecyclerView . Now I want to display an AlertDialog when an item of RecyclerView is clicked. I tried many ways and none of them worked. Here is my adapter class,

**Parent Adopter class code**'
$ package com.pscripto.mxmoviehub;
import android.annotation.SuppressLint; import android.app.Dialog; import android.content.Context; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.LinearLayout; import android.widget.TextView; import android.widget.Toast;
import androidx.annotation.NonNull; import androidx.recyclerview.widget.ItemTouchHelper; import androidx.recyclerview.widget.LinearLayoutManager; import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList; import java.util.List;
public class ParentAdopter extends RecyclerView.Adapter<ParentAdopter.ParentAdopterViewHolder> { private List<Movie_Model> movieModelList; private List<Child_Model> child_modelList; private ChildAdopter childAdopter; private Context context;
public ParentAdopter(#NonNull List<Movie_Model> movieModelList) {
this.movieModelList = movieModelList;
}
#NonNull
#Override
public ParentAdopterViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View rootview = LayoutInflater.from(parent.getContext()).inflate(R.layout.vertical_rv,parent,false);
return new ParentAdopterViewHolder(rootview);
}
#SuppressLint("WrongConstant")
#Override
public void onBindViewHolder(#NonNull ParentAdopterViewHolder holder, int position) { Movie_Model movie_model = movieModelList.get(position); holder.tvSection.setText(movie_model.getHeaderTitle()); if (movie_model.getHeaderTitle().contains("Latest Movies")){ childAdopter= new ChildAdopter(getLatestMovie(),context);
} else if (movie_model.getHeaderTitle().contains("Action Movies")){
childAdopter= new ChildAdopter(getActionMovies(),context);
} else if (movie_model.getHeaderTitle().contains("Romantic Movies")){
childAdopter = new ChildAdopter(getRomanticMovies(),context); } holder.childRecyclerview.setHasFixedSize(true); holder.childRecyclerview.setLayoutManager(new LinearLayoutManager(context, LinearLayout.HORIZONTAL,false)); holder.childRecyclerview.setAdapter(childAdopter); //customClicl();
} private void customClicl(){
childAdopter.setCustomClickListener(new ChildAdopter.CustomClickListener() {
#Override
public void onItemClick(int position) {
Toast.makeText(context, "hi", Toast.LENGTH_SHORT).show();
}
}); }
private List<Child_Model> getLatestMovie(){ child_modelList = new ArrayList<>(); child_modelList.add(new Child_Model(R.drawable.salmankhanmovieone,"Bajrangi Bhaijaan"));
child_modelList.add(new Child_Model(R.drawable.pati,"Pati Patni Aur Woh"));
child_modelList.add(new Child_Model(R.drawable.blackmail,"Blackmail 2019"));
child_modelList.add(new Child_Model(R.drawable.bharat,"Bharat 2019"));
child_modelList.add(new Child_Model(R.drawable.gang,"Gangster 3"));
return child_modelList;
}
private List<Child_Model> getActionMovies(){
child_modelList = new ArrayList<>();
child_modelList.add(new Child_Model(R.drawable.salmankhanmovieone,"Bajrangi Bhaijaan"));
child_modelList.add(new Child_Model(R.drawable.blackmail,"Blackmail 2019"));
child_modelList.add(new Child_Model(R.drawable.bharat,"Bharat 2019"));
child_modelList.add(new Child_Model(R.drawable.gang,"Gangster 3"));
return child_modelList;
}
private List<Child_Model> getRomanticMovies(){
child_modelList = new ArrayList<>();
child_modelList.add(new Child_Model(R.drawable.star,"Love Star"));
child_modelList.add(new Child_Model(R.drawable.bestofme,"The Best Of Me"));
child_modelList.add(new Child_Model(R.drawable.trailer,"After Trailer"));
child_modelList.add(new Child_Model(R.drawable.buylove,"Cant Buy Love"));
return child_modelList;
}
#Override
public int getItemCount() {
return movieModelList.size();
}
class ParentAdopterViewHolder extends RecyclerView.ViewHolder { TextView tvSection; RecyclerView childRecyclerview;
public ParentAdopterViewHolder(#NonNull View itemView) {
super(itemView);
tvSection = itemView.findViewById(R.id.tvsection);
childRecyclerview = itemView.findViewById(R.id.child_rv);
}
}
}'$'

**Child adopter class**
package com.pscripto.mxmoviehub;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AlertDialog;
import androidx.recyclerview.widget.ItemTouchHelper;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;
public class ChildAdopter extends RecyclerView.Adapter<ChildAdopter.ChildAdopterViewHolder> {
private List<Child_Model> child_modelList;
private ChildAdopter childAdopter ;
private Context context;
private CustomClickListener customClickListener;
public void setCustomClickListener(CustomClickListener customClickListener) {
this.customClickListener = customClickListener;
}
interface CustomClickListener{
void onItemClick (int position);
}
public ChildAdopter(List<Child_Model> child_modelList, Context context) {
this.child_modelList = child_modelList;
this.context = context;
}
#NonNull
#Override
public ChildAdopterViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View rootview = LayoutInflater.from(parent.getContext()).inflate(R.layout.horizental_layout, parent, false);
return new ChildAdopterViewHolder(rootview);
}
#Override
public void onBindViewHolder(#NonNull ChildAdopterViewHolder holder, int position) {
Child_Model child_model = child_modelList.get(position);
holder.movieImg.setImageResource(child_model.getImgResId());
holder.movieTitle.setText(child_model.getTitle());
Boolean isExpanded = child_modelList.get(position).getExpanded();
holder.expandidLayout.setVisibility(isExpanded ? View.VISIBLE : View.INVISIBLE);
}
#Override
public int getItemCount() {
return child_modelList.size();
}
class ChildAdopterViewHolder extends RecyclerView.ViewHolder {
private ImageView movieImg ,ivEdit,ivDel;
private TextView movieTitle;
LinearLayout expandidLayout;
public ChildAdopterViewHolder(#NonNull View itemView) {
super(itemView);
movieImg = itemView.findViewById(R.id.movie_img);
movieTitle = itemView.findViewById(R.id.movie_name);
expandidLayout = itemView.findViewById(R.id.expandable_layout);
ivEdit = itemView.findViewById(R.id.iv_Edit);
ivDel = itemView.findViewById(R.id.del_img);
movieTitle.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int position = getAdapterPosition();
Child_Model child_model = child_modelList.get(position);
child_model.setExpanded(!child_model.getExpanded());
notifyItemChanged(getAdapterPosition());
}
});
ivEdit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int position= getAdapterPosition();
if (customClickListener != null){
customClickListener.onItemClick(position);
}
}
});
}
}
}

RecyclerView is not displaying any data from the firestore

I have list of Categories of Subjects in my firestore database and i want it to be displayed in my app ( which i thought can be done by recyclerView).But my RecyclerView is not populating any data.You can see my code below:
Question_list.java
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import com.google.firebase.firestore.DocumentChange;
import com.google.firebase.firestore.EventListener;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.FirebaseFirestoreException;
import com.google.firebase.firestore.QuerySnapshot;
import java.util.ArrayList;
import java.util.List;
import javax.annotation.Nullable;
public class Question_list extends AppCompatActivity {
private static final String TAG ="Firelog" ;
private RecyclerView mMainList;
private FirebaseFirestore mFirestore;
private CategoryAdapter categoryAdapter;
private List<Categories> list_category;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_question_list);
mMainList = (RecyclerView)findViewById(R.id.main_list_id);
//mMainList.setHasFixedSize(true);
mMainList.setLayoutManager(new LinearLayoutManager(this));
mMainList.setAdapter(categoryAdapter);
mFirestore = FirebaseFirestore.getInstance();
categoryAdapter = new CategoryAdapter(list_category);
list_category = new ArrayList<>();
mFirestore.collection("Questions").addSnapshotListener(new EventListener<QuerySnapshot>() {
#Override
public void onEvent(#Nullable QuerySnapshot queryDocumentSnapshots, #Nullable FirebaseFirestoreException e) {
if(e!=null){
Log.d(TAG, "Error: "+ e.getMessage());
}
for(DocumentChange doc: queryDocumentSnapshots.getDocumentChanges()){
if(doc.getType() == DocumentChange.Type.MODIFIED){
//String document = doc.getDocument().getString("Category");
Categories categories = doc.getDocument().toObject(Categories.class);
list_category.add(categories);
Log.d(TAG, "Category: "+ categories);
categoryAdapter.notifyDataSetChanged();
}
}
}
});
}
}
CategoryAdapter.java
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.List;
public class CategoryAdapter extends
RecyclerView.Adapter<CategoryAdapter.ViewHolder> {
public List<Categories> list_categorie;
public CategoryAdapter(List<Categories> list_categorie){
this.list_categorie = list_categorie;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.category_list,parent,false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
holder.mCategoryText.setText(list_categorie.get(position).getCategory());
}
#Override
public int getItemCount() {
return list_categorie.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
View mview;
public TextView mCategoryText;
public ViewHolder(View itemView) {
super(itemView);
mview = itemView;
mCategoryText = (TextView)mview.findViewById(R.id.category_text_id);
}
}
}
Categories.java
public class Categories {
String category;
public Categories(){}
public Categories(String category) {
this.category = category;
}
public String getCategory() {
return category;
}
}
Above are my all java classes. I haven't uploaded my XML file as i think the problem is in the java class.

categoryAdapter = new CategoryAdapter(list_category);
list_category = new ArrayList<>();
list_category should be initialized before passing it to the adapter
list_category = new ArrayList<>();
categoryAdapter = new CategoryAdapter(list_category);