¿Cómo recuperar datos de la base de datos de firebase que está teniendo matriz anidada y estructura de objetos?

He intentado código de extracción de datos de muchos lugares, pero en todas partes consigo cómo recuperar datos en una lista simple. Como la estructura de mi JSON es compleja y no puedo cambiarla ahora, así que por favor ayúdame a recuperar datos de la base de datos de firebase. Por favor ayuda, ya que no soy capaz de entender el código de Firebase . A continuación se muestra mi código y la base de datos JSON:

CategoryModel.xml

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package com.example.firedb; import android.os.Parcel; import android.os.Parcelable; import java.util.ArrayList; /** * Created by Android on 5/31/2017. */ public class CategoryModel { private ArrayList<CategoryList> categoryList; public CategoryModel() { } public CategoryModel(ArrayList<CategoryList> categoryList) { this.categoryList = categoryList; } public ArrayList<CategoryList> getCategoryList() { return categoryList; } public void setCategoryList(ArrayList<CategoryList> categoryList) { this.categoryList = categoryList; } // CategoryList public static class CategoryList { public int Category_id; public String Category_name; public ArrayList<String>Emails; public ArrayList<String>Epabx; public ArrayList<String>Category_Fax; public ArrayList<Persons> persons; public CategoryList() { } //constructor of CategoryList public CategoryList(int category_id, String category_name, ArrayList<String> emails, ArrayList<String> epabx, ArrayList<String> category_Fax, ArrayList<Persons> persons) { Category_id = category_id; Category_name = category_name; Emails = emails; Epabx = epabx; Category_Fax = category_Fax; this.persons = persons; } // getters and setters of CategoryList public int getCategory_id() { return Category_id; } public void setCategory_id(int category_id) { Category_id = category_id; } public String getCategory_name() { return Category_name; } public void setCategory_name(String category_name) { Category_name = category_name; } public ArrayList<String> getEmails() { return Emails; } public void setEmails(ArrayList<String> emails) { Emails = emails; } public ArrayList<String> getEpabx() { return Epabx; } public void setEpabx(ArrayList<String> epabx) { Epabx = epabx; } public ArrayList<String> getCategory_Fax() { return Category_Fax; } public void setCategory_Fax(ArrayList<String> category_Fax) { Category_Fax = category_Fax; } public ArrayList<Persons> getPersons() { return persons; } public void setPersons(ArrayList<Persons> persons) { this.persons = persons; } } //Persons public static class Persons { private int Person_ID; private String Name; private String Designation; private ArrayList<String> Office_Phone; private ArrayList<String> Residence_Phone; private String VOIP; private String Address; private ArrayList<String>Fax; private String Ext; private ArrayList<String>Extra_info; private String Category_name; public Persons() { } // Constructor of Persons public Persons(int person_ID, String name, String designation, ArrayList<String> office_Phone, ArrayList<String> residence_Phone, String VOIP, String address, ArrayList<String> fax, String ext, ArrayList<String>extra_info, String category_name) { Person_ID = person_ID; Name = name; Designation = designation; Office_Phone = office_Phone; Residence_Phone = residence_Phone; this.VOIP = VOIP; Address = address; Fax = fax; Ext = ext; Extra_info=extra_info; Category_name=category_name; } // Getter and Setters of Persons public int getPerson_ID() { return Person_ID; } public void setPerson_ID(int person_ID) { Person_ID = person_ID; } public String getName() { return Name; } public void setName(String name) { Name = name; } public String getDesignation() { return Designation; } public void setDesignation(String designation) { Designation = designation; } public ArrayList<String> getOffice_Phone() { return Office_Phone; } public void setOffice_Phone(ArrayList<String> office_Phone) { Office_Phone = office_Phone; } public ArrayList<String> getResidence_Phone() { return Residence_Phone; } public void setResidence_Phone(ArrayList<String> residence_Phone) { Residence_Phone = residence_Phone; } public String getVOIP() { return VOIP; } public void setVOIP(String VOIP) { this.VOIP = VOIP; } public String getAddress() { return Address; } public void setAddress(String address) { Address = address; } public ArrayList<String> getFax() { return Fax; } public void setFax(ArrayList<String> fax) { Fax = fax; } public String getExt() { return Ext; } public void setExt(String ext) { Ext = ext; } public ArrayList<String> getExtra_info() { return Extra_info; } public void setExtra_info(ArrayList<String> extra_info) { Extra_info = extra_info; } public String getCategory_name() { return Category_name; } public void setCategory_name(String category_name) { Category_name = category_name; } } } 

CardviewActivity: Anteriormente he utilizado un archivo de activos, pero ahora quiero obtener datos de firebase cuyo código es ambiguo en línea

 package com.example.firedb; import android.content.Intent; import android.graphics.Color; import android.graphics.drawable.Drawable; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.support.v7.widget.Toolbar; import android.text.Editable; import android.text.LoginFilter; import android.text.TextWatcher; import android.util.Log; import android.view.Gravity; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.RelativeLayout; import android.widget.TextView; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import java.io.IOException; import java.io.InputStream; import java.util.ArrayList; import static android.R.attr.button; public class CardViewActivity extends AppCompatActivity { Toolbar mActionBarToolbar; private RecyclerView mainRecyclerView; private RecyclerView.Adapter mainAdapter; private RecyclerView.LayoutManager mainLayoutManager; private static String LOG_TAG = "CardViewActivity"; EditText inputSearchMain; private ArrayList<CategoryModel.CategoryList> categoryLists; TextView toolbar_title_main; ImageView back_cardviewActivity; // DatabaseHandler db; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_card_view); // db = new DatabaseHandler (CardViewActivity.this); mActionBarToolbar = (Toolbar) findViewById(R.id.tool_bar); toolbar_title_main=(TextView)findViewById(R.id.toolbar_title); // mActionBarToolbar.setTitle("Hry. Govt. Telephone Directory"); // mActionBarToolbar.setLogo(R.drawable.logotoolbar); // mActionBarToolbar.setTitleMargin(5,2,2,2); setSupportActionBar(mActionBarToolbar); getSupportActionBar().setDisplayShowTitleEnabled(false); toolbar_title_main.setText("Hry. Govt. Telephone Directory"); back_cardviewActivity=(ImageView)findViewById(R.id.back); back_cardviewActivity.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { onBackPressed(); } }); categoryLists=new ArrayList<CategoryModel.CategoryList>(); categoryLists.addAll(getmcategoryset()); mainRecyclerView=(RecyclerView)findViewById(R.id.recyclerView_Main); mainRecyclerView.setHasFixedSize(true); mainLayoutManager=new LinearLayoutManager(this); mainRecyclerView.setLayoutManager(mainLayoutManager); // Log.d( "onCreate: ", "List Size: "+categoryLists.size()); mainAdapter=new RecyclerViewAdapterMain(getmcategoryset()); mainRecyclerView.setAdapter(mainAdapter); inputSearchMain = (EditText) findViewById(R.id.inputSearchMain); addTextListener(); } public void addTextListener(){ inputSearchMain.addTextChangedListener(new TextWatcher() { public void afterTextChanged(Editable s) {} public void beforeTextChanged(CharSequence s, int start, int count, int after) {} public void onTextChanged(CharSequence query, int start, int before, int count) { query = query.toString().toLowerCase(); final ArrayList<CategoryModel.CategoryList> filteredList = new ArrayList<CategoryModel.CategoryList>(); for (int i = 0; i < categoryLists.size(); i++) { final String text = categoryLists.get(i).getCategory_name().toLowerCase(); if (text.contains(query)) { filteredList.add(categoryLists.get(i)); } } mainRecyclerView.setLayoutManager(new LinearLayoutManager(CardViewActivity.this)); mainAdapter = new RecyclerViewAdapterMain(filteredList); mainRecyclerView.setAdapter(mainAdapter); mainAdapter.notifyDataSetChanged(); // data set changed } }); } private ArrayList<CategoryModel.CategoryList> getmcategoryset() { // JSONObject obj = new JSONObject(readJSONFromAsset()); try { ArrayList<CategoryModel.CategoryList>categoryList = new ArrayList<CategoryModel.CategoryList>(); JSONObject jsonObject = new JSONObject(readJSONFromAsset()); JSONArray categoryArray = jsonObject.getJSONArray("Category"); Log.d("getmcategoryset", "category count: "+categoryArray.length()); for (int i = 0; i < categoryArray.length(); i++) { JSONObject job = categoryArray.getJSONObject(i); int categoryId = job.getInt("Category_id"); String categoryName = job.getString("Category_name"); //this is for email array ArrayList<String> emails = new ArrayList<>(); JSONArray emailArray = job.getJSONArray("Emails"); for (int j = 0; j< emailArray.length(); j++){ // JSONObject jobE = emailArray.getString(j); emails.add(emailArray.getString(j)); } //This i for Epabx array ArrayList<String> epabx = new ArrayList<>(); JSONArray epabxArray = job.getJSONArray("Epabx"); for (int j = 0; j < epabxArray.length(); j++){ // JSONObject jobE = epabxArray.getString(j); epabx.add(epabxArray.getString(j)); } //This i for Category_Fax array ArrayList<String> category_Fax = new ArrayList<>(); JSONArray category_FaxJson = job.getJSONArray("Category_Fax"); for (int j = 0; j < category_FaxJson.length(); j++){ // JSONObject jobE = category_FaxJson.getString(j); category_Fax.add(category_FaxJson.getString(j)); } //This i for Persons array ArrayList<CategoryModel.Persons> personsList = new ArrayList<>(); JSONArray personsArray = job.getJSONArray("Persons"); for (int j = 0; j < personsArray.length(); j++){ JSONObject jobIn = personsArray.getJSONObject(j); int Person_ID = jobIn.getInt("Person_ID"); String Name = jobIn.getString("Name"); String Designation = jobIn.getString("Designation"); //this is for Office_Phone array ArrayList<String>Office_Phone = new ArrayList<>(); JSONArray office_Phone = jobIn.getJSONArray("Office_Phone"); for (int k=0; k < office_Phone.length(); k++) { Office_Phone.add(office_Phone.getString(k)); } //this is for Residence_Phone array ArrayList<String>Residence_Phone = new ArrayList<>(); JSONArray residence_Phone = jobIn.getJSONArray("Residence_Phone"); for (int k=0; k < residence_Phone.length(); k++) { Residence_Phone.add(residence_Phone.getString(k)); } String VOIP = jobIn.getString("VOIP"); String Address = jobIn.getString("Address"); //this is for Fax array ArrayList<String>Fax = new ArrayList<>(); JSONArray fax = jobIn.getJSONArray("Fax"); for (int k=0; k < fax.length(); k++) { Fax.add(fax.getString(k)); } String Ext = jobIn.getString("Ext"); //this is for Extra_info array ArrayList<String>Extra_info = new ArrayList<>(); JSONArray extra_info = jobIn.getJSONArray("Extra_info"); for (int k=0; k < extra_info.length(); k++) { Extra_info.add(extra_info.getString(k)); } personsList.add(new CategoryModel.Persons(Person_ID, Name, Designation, Office_Phone, Residence_Phone, VOIP, Address, Fax, Ext,Extra_info,categoryName)); // db.addPerson(new CategoryModel.Persons(Person_ID, Name, Designation, Office_Phone, Residence_Phone, // VOIP, Address, Fax, Ext,Extra_info)); } //here your Category[] value store in categoryArrayList categoryList.add(new CategoryModel.CategoryList(categoryId, categoryName, emails, epabx, category_Fax, personsList)); // db.addCategory(new CategoryModel.CategoryList(categoryId, categoryName, emails, epabx, category_Fax, personsList)); Log.i("categoryList size = ", ""+categoryArray.length()); Log.i("cat_name=",""+categoryName); } if (categoryList != null) { Log.i("categoryList size = ", ""+categoryArray.length()); } return categoryList; } catch (JSONException e) { e.printStackTrace(); return null; } } @Override protected void onResume() { super.onResume(); // ((RecyclerViewAdapterMain) mainAdapter).setOnItemClickListener(new RecyclerViewAdapterMain() // .CategoryClickListener() { // public void onItemClick(int position, View v) { // Log.i(LOG_TAG, " Clicked on Item " + position); // } // }); } } 

RecyclerViewAdapter:

 package com.example.firedb; import android.content.Context; import android.content.Intent; import android.os.Bundle; import android.support.v7.widget.RecyclerView; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.TextView; import java.util.ArrayList; import java.util.Arrays; public class RecyclerViewAdapterMain extends RecyclerView.Adapter<RecyclerViewAdapterMain.CategoryObjectHolder> { private static String LOG_TAG = "categoryRecyclrVwAdptr"; private ArrayList<CategoryModel.CategoryList> mcategoryset; private static CategoryClickListener categoryClickListener; public static class CategoryObjectHolder extends RecyclerView.ViewHolder { TextView category_name; /*TextView category_emails; TextView category_epabx; TextView category_fax;*/ public CategoryObjectHolder(View itemView){ super(itemView); category_name=(TextView)itemView.findViewById(R.id.category_name); /*category_emails=(TextView)itemView.findViewById(R.id.category_emails); category_epabx=(TextView)itemView.findViewById(R.id.category_epabx); category_fax=(TextView)itemView.findViewById(R.id.category_fax);*/ Log.i(LOG_TAG, "Adding Listener"); } // @Override // public void onClick(View v) { // categoryClickListener.onItemClick(getAdapterPosition(), v); // } } // public void setOnItemClickListener(CategoryClickListener categoryClickListener) { // this.categoryClickListener = categoryClickListener; // } public RecyclerViewAdapterMain(ArrayList<CategoryModel.CategoryList> myDataset) { mcategoryset = myDataset; } public CategoryObjectHolder onCreateViewHolder(ViewGroup parent,int viewType){ View view= LayoutInflater.from(parent.getContext()).inflate(R.layout.card_view_row_main_activity,parent,false); CategoryObjectHolder categoryObjectHolder=new CategoryObjectHolder(view); return categoryObjectHolder; } @Override public void onBindViewHolder(CategoryObjectHolder holder, final int position) { /*final StringBuilder stringBuilder_emails = new StringBuilder(); for (String email : mcategoryset.get(position).getEmails()) { if (!stringBuilder_emails.toString().isEmpty()) { stringBuilder_emails.append(", "); } stringBuilder_emails.append(email); } final StringBuilder stringBuilder_Epabx = new StringBuilder(); for (String epabx : mcategoryset.get(position).getEpabx()) { if (!stringBuilder_Epabx.toString().isEmpty()) { stringBuilder_Epabx.append(", "); } stringBuilder_Epabx.append(epabx); } final StringBuilder stringBuilder_Category_Fax = new StringBuilder(); for (String category_Fax : mcategoryset.get(position).getCategory_Fax()) { if (!stringBuilder_Category_Fax.toString().isEmpty()) { stringBuilder_Category_Fax.append(", "); } stringBuilder_Category_Fax.append(category_Fax); }*/ holder.category_name.setText(mcategoryset.get(position).getCategory_name()); /*holder.category_emails.setText(stringBuilder_emails.toString()); holder.category_epabx.setText(stringBuilder_Epabx.toString()); holder.category_fax.setText(stringBuilder_Category_Fax.toString());*/ holder.itemView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Intent i = new Intent (v.getContext(), PeopleListActivity.class); i.putParcelableArrayListExtra("Persons",mcategoryset.get(position).getPersons()); i.putStringArrayListExtra("emails",mcategoryset.get(position).getEmails()); //i.putExtras(b); v.getContext().startActivity(i); } }); } public void addItem(CategoryModel.CategoryList dataObj, int index) { mcategoryset.add(index, dataObj); notifyItemInserted(index); } public void deleteItem(int index) { mcategoryset.remove(index); notifyItemRemoved(index); } @Override public int getItemCount() { return mcategoryset.size(); } public interface CategoryClickListener { public void onItemClick(int position, View v); } } 

 CategoryModel categoryModel; ArrayList<CategoryList> array = new ArrayList<>(); FirebaseDatabase database = FirebaseDatabase.getInstance(); DatabaseReference categoryRef = database.getReference("Category"); categoryRef.addValueEventListener(new ValueEventListener() { @Override public void onDataChange(DataSnapshot dataSnapshot) { // This method is called once with the initial value and again // whenever data at this location is updated. for (DataSnapshot childSnapshot: dataSnapshot.getChildren()) { CategoryList categoryList = childSnapshot.getValue(CategoryList.class); array.add(categoryList); } categoryModel = new CategoryModel(array); // Method to show the data in category model, // usually populating an ListView or something updateUI() } @Override public void onCancelled(DatabaseError error) { // Failed to read value Log.w(TAG, "Failed to read value.", error.toException()); } }); 

 public CategoryList(DataSnapshot snapshot){ Category_id = snapshot.child("Category_id").getValue(int.class); Category_name = snapshot.child("Category_name").getValue(String.class); GenericTypeIndicator<List<String>> stringList = new GenericTypeIndicator<List<String>>() {}; Emails = snapshot.child("Emails").getValue(stringList); Epabx= snapshot.child("Epabx").getValue(stringList); Category_Fax= snapshot.child("Category_Fax").getValue(stringList); GenericTypeIndicator<List<Persons>> personsList = new GenericTypeIndicator<List<Persons>>() {}; persons = snapshot.child("Persons").getValue(personsList); } 

 CategoryList categoryList = childSnapshot.getValue(CategoryList.class); 

 CategoryList categoryList = new CategoryList(childSnapshot); 

 -Category --CategoryId ---CategoryList ---Persons ----user1: true ----user2: true, etc. -Users --user1Id ---user1details --user2Id ---user2details, etc.