Develop Reference

How to update room database based on server response

I am fetching data from server and saving in room database and then from room showing it in recycler view.Data is perfectly saving in room database and showing in recycler view.
Problem: When I am deleting some data from server database then its old copy that saved earlier still persists in room.
What I want: I don't want to show data deleted from server in recycler view.So how can I update room database based on server response.
This is what I have done so far:
UserDao.java
#Dao
public interface UserDao {
#Insert(onConflict = OnConflictStrategy.REPLACE)
void Insert(User... users);
#Query("SELECT * FROM Users")
LiveData<List<User>> getRoomUsers();
}
User.java
#Entity(tableName = "Users")
public class User {
#NonNull
#PrimaryKey
private String id;
#ColumnInfo(name = "name")
#SerializedName("name")
#Expose
private String name;
#ColumnInfo(name = "age")
#SerializedName("age")
#Expose
private String age;
public User(String id,String name, String age) {
this.id = id;
this.name = name;
this.age = age;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
}
UserRepository.java
public class UserRepository {
private Context context;
private UserDb userDb;
private LiveData<List<User>> listLiveData;
public UserRepository(Context context) {
this.context = context;
userDb = UserDb.getInstance(context);
listLiveData = userDb.userDao().getRoomUsers();
}
public void getUserList(){
Retrofit retrofit = RetrofitClient.getInstance();
ApiService apiService = retrofit.create(ApiService.class);
Call<List<User>> userList = apiService.getUser();
userList.enqueue(new Callback<List<User>>() {
#Override
public void onResponse(Call<List<User>> call, final Response<List<User>> response) {
Completable.fromAction(new Action() {
#Override
public void run() throws Exception {
if(response.body() != null) {
List<User> list = response.body();
for (int i = 0; i < list.size(); i++) {
String id = list.get(i).getId();
String names = list.get(i).getName();
String age = list.get(i).getAge();
User user = new User(id,names,age);
userDb.userDao().Insert(user);
}
}
}
}).subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new CompletableObserver() {
#Override
public void onSubscribe(Disposable d) {
}
#Override
public void onComplete() {
Toast.makeText(context,"Data inserted",Toast.LENGTH_SHORT).show();
}
#Override
public void onError(Throwable e) {
Toast.makeText(context,e.getMessage(),Toast.LENGTH_SHORT).show();
}
});
}
#Override
public void onFailure(Call<List<User>> call, Throwable t) {
Toast.makeText(context,t.getMessage(),Toast.LENGTH_LONG).show();
}
});
}
public LiveData<List<User>> getRoomUsers(){
return listLiveData;
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity {
UserRepository userRepository;
RecyclerView recyclerView;
UserViewModel userModel;
List<User> userList;
UserAdapter adapter;
ProgressBar prg;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
prg = findViewById(R.id.prg);
userRepository = new UserRepository(this);
userModel = ViewModelProviders.of(this).get(UserViewModel.class);
recyclerView = findViewById(R.id.recyclerView);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
userList = new ArrayList<>();
adapter = new UserAdapter(userList,this);
recyclerView.setAdapter(adapter);
userModel.getListLiveData().observe(this, new Observer<List<User>>() {
#Override
public void onChanged(List<User> users) {
prg.setVisibility(View.INVISIBLE);
adapter.setUserList(users);
}
});
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(MainActivity.this,AddUser.class);
startActivity(i);
}
});
userRepository.getUserList();
}
Someone please let me know how can I get desired result. Any help would be appreciated.
THANKS

Use getRoomUsers() to get a list of known users from the repository in onResponse().
For each user in response.body(), check if it has a corresponding list item in the known users' list. Remove this item.
Afterwards, the list of known users will contain only users which have been deleted from the server. So for each of these remaining users, you can delete them from the room database.
The following code snippet shows how to find the users which are currently not known to the server:
if (response.body() != null) {
List<User> list = response.body();
List<User> previouslyKnownUsers = new ArrayList<>(userDb.userDao().getRoomUsers().getValue());
for (int i = 0; i < list.size(); i++) {
String id = list.get(i).getId();
String names = list.get(i).getName();
String age = list.get(i).getAge();
User user = new User(id, names, age);
userDb.userDao().Insert(user);
User knownUser = null;
for(User previouslyKnownUser: previouslyKnownUsers){
if(previouslyKnownUser.getId().equals(user.getId())){
knownUser = previouslyKnownUser;
break;
}
}
if(knownUser != null){
previouslyKnownUsers.remove(knownUser);
}
}
for(User currentlyUnknownUser: previouslyKnownUsers){
userDb.userDao().Delete(currentlyUnknownUser);
}
}
In order to make it work, you have to add a method Delete(User user) in UserDao.java

Data fetched from server is copying multiple times in room database

In my app I am using room as a database cache.I am fetching data from server using retrofit library and saving the data inside room database and showing the same data from room in recycler view.
Problem: Whenever activity starts it fetches data from server and saving it in room database due to which same data showing multiple times in recycler view.
What I want: I want to know how can I check if data already present in room should not save multiple time in room and if some new data updated on server it should fetch new data and save it to the room database.
This is what I have done so far:
UserDao.java
#Dao
public interface UserDao {
#Insert(onConflict = OnConflictStrategy.REPLACE)
void Insert(User... users);
#Query("SELECT * FROM Users")
LiveData<List<User>> getRoomUsers();
}
User.java
#Entity(tableName = "Users")
public class User {
#PrimaryKey
private String id;
#ColumnInfo(name = "name")
#SerializedName("name")
#Expose
private String name;
#ColumnInfo(name = "age")
#SerializedName("age")
#Expose
private String age;
public User(String id,String name, String age) {
this.id = id;
this.name = name;
this.age = age;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
}
UserRepository.java
public class UserRepository {
private Context context;
private UserDb userDb;
private LiveData<List<User>> listLiveData;
public UserRepository(Context context) {
this.context = context;
userDb = UserDb.getInstance(context);
listLiveData = userDb.userDao().getRoomUsers();
}
public void getUserList(){
Retrofit retrofit = RetrofitClient.getInstance();
ApiService apiService = retrofit.create(ApiService.class);
Call<List<User>> userList = apiService.getUser();
userList.enqueue(new Callback<List<User>>() {
#Override
public void onResponse(Call<List<User>> call, final Response<List<User>> response) {
Completable.fromAction(new Action() {
#Override
public void run() throws Exception {
if(response.body() != null) {
List<User> list = response.body();
for (int i = 0; i < list.size(); i++) {
String names = list.get(i).getName();
String age = list.get(i).getAge();
String id = UUID.randomUUID().toString();
User user = new User(id,names,age);
userDb.userDao().Insert(user);
}
}
}
}).subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new CompletableObserver() {
#Override
public void onSubscribe(Disposable d) {
}
#Override
public void onComplete() {
Toast.makeText(context,"Data inserted",Toast.LENGTH_SHORT).show();
}
#Override
public void onError(Throwable e) {
Toast.makeText(context,e.getMessage(),Toast.LENGTH_SHORT).show();
}
});
}
#Override
public void onFailure(Call<List<User>> call, Throwable t) {
Toast.makeText(context,t.getMessage(),Toast.LENGTH_LONG).show();
}
});
}
public LiveData<List<User>> getRoomUsers(){
return listLiveData;
}
}
UserViewModel.java
public class UserViewModel extends AndroidViewModel {
private UserRepository repo;
private LiveData<List<User>> listLiveData;
public UserViewModel(#NonNull Application application) {
super(application);
repo = new UserRepository(application);
listLiveData = repo.getRoomUsers();
}
public LiveData<List<User>> getListLiveData() {
return listLiveData;
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity {
UserRepository userRepository;
RecyclerView recyclerView;
UserViewModel userModel;
List<User> userList;
UserAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
userRepository = new UserRepository(this);
userModel = ViewModelProviders.of(this).get(UserViewModel.class);
recyclerView = findViewById(R.id.recyclerView);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
userList = new ArrayList<>();
adapter = new UserAdapter(userList,this);
recyclerView.setAdapter(adapter);
userModel.getListLiveData().observe(this, new Observer<List<User>>() {
#Override
public void onChanged(List<User> users) {
adapter.setUserList(users);
}
});
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(MainActivity.this,AddUser.class);
startActivity(i);
}
});
userRepository.getUserList();
}
In MainActivity.java userRepository.getUserList() fetches data from server and save it in room database.
Some one please let me know how can I get desired result. Any help would be appreciated.
THANKS

As #a_local_nobody says add this to your Dao.
#Insert(onConflict = OnConflictStrategy.REPLACE)
But this will not fully solve your problem. If you see SQLite doc it says
The ON CONFLICT clause applies to UNIQUE, NOT NULL, CHECK, and PRIMARY KEY constraints. The ON CONFLICT algorithm does not apply to FOREIGN KEY constraints.
Your entity defines a Primary Key but it is tagged with autoGenerate = true. Due to this whenever you create a new User instance and calling insert on your Dao Room is generating a new primary key. This id does not conflict with the "duplicate" User in your db, and hence Room is happy to insert this one without touching the previous "duplicate" version.
The solution is to have the Primary Key from the backend or have a UNIQUE constraint on one field of User entity.

consider looking at this annotation for room :
#Insert(onConflict = OnConflictStrategy.REPLACE)
with this, if you insert anything which already exists, it will simply replace it.
where you are calling :
#Override
public void onChanged(List<User> users) {
adapter.setUserList(users);
}
try clearing the list of the adapter first

anyone looking in the future. The best possible way to do this is to delete the table before inserting new data. e.g.
in your #Dao class define #delete query
#Query("DELETE FROM Users")
void deleteAllUsersData();
and call this query every time before inserting new data into the database. if you want the same primary key then set #Primary key autogenerate to false.

Unable to retrieve firestore database using recyclerView

I am using recyclerView and Adapter to fetch the data in profileActivity
here is my
public class studentDetailsRecyclerActivity extends AppCompatActivity {
//recyclerview to set the details for UI in the student profile activity
private RecyclerView mRecyclerView;
private storeDetailsAdapter mStoreDetailsAdapter;
private List<storeStudentDetails> studentDetailsList;
private FirebaseFirestore dbReference;
private ProgressBar mProgressBar;
private String TAG = studentDetailsRecyclerActivity.class.getSimpleName();
#Override
protected void onCreate(Bundle savedInstanceState) {
dbReference = FirebaseFirestore.getInstance();
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_recycler_details);
mProgressBar = findViewById(R.id.progressbar);
mRecyclerView = (RecyclerView)findViewById(R.id.recyclerView_products);
mRecyclerView.setHasFixedSize(true);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
studentDetailsList = new ArrayList<>();
mStoreDetailsAdapter = new storeDetailsAdapter(this,studentDetailsList);
mRecyclerView.setAdapter(mStoreDetailsAdapter);
//to get the "details" this is our collection from firestore so we must fetch them
//by calling the addOnSuccessListener
dbReference.collection("details").get()
.addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
#Override
public void onSuccess(QuerySnapshot queryDocumentSnapshots) { //we must have to hide the progress bar when the data gets loaded
//here queryDocumentsSnapshot will hold all the "details" which is your collection in firestore
if(!queryDocumentSnapshots.isEmpty()){
//we must have to create empty list so that to store all
//details from DocumentsSnapshots
List<DocumentSnapshot> list = queryDocumentSnapshots.getDocuments();
//enhanced for loop because we have to give every index documentSnapShot
for(DocumentSnapshot d: list){
storeStudentDetails sd = d.toObject(storeStudentDetails.class);
studentDetailsList.add(sd);
Log.d(TAG, "onSuccess: " + sd.toString());
}
//to refresh and sync we must have to use notifyDataSetChanged
mStoreDetailsAdapter.notifyDataSetChanged();
}
}
}) .addOnFailureListener(new OnFailureListener() {
#Override
public void onFailure(#NonNull Exception e) {
Toast.makeText(getApplicationContext(), "Error getting data!!!", Toast.LENGTH_LONG).show();
}
});
}
}
and here is my storeDetailsAdapter
import java.util.List;
public class storeDetailsAdapter extends RecyclerView.Adapter<storeDetailsAdapter.StudentViewHolder>{
private Context context;
private List<storeStudentDetails> studentDetailsList;
public storeDetailsAdapter(Context context, List<storeStudentDetails> studentDetailsList) {
this.context = context;
this.studentDetailsList = studentDetailsList;
}
#NonNull
#Override
public StudentViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
return new StudentViewHolder(
LayoutInflater.from(context).inflate(R.layout.profile_activity, parent, false)
);
}
#Override
public void onBindViewHolder(#NonNull StudentViewHolder holder, int position) {
storeStudentDetails mStoreDetails = studentDetailsList.get(position);
holder.studName.setText(mStoreDetails.getStudentName());
holder.rollNum.setText(mStoreDetails.getRollNo());
holder.bookName.setText( mStoreDetails.getBook());
holder.fine.setText("Fine:" + mStoreDetails.getFine());
holder.dept.setText(mStoreDetails.getDept());
}
#Override
public int getItemCount() {
return studentDetailsList.size();
}
class StudentViewHolder extends RecyclerView.ViewHolder {
TextView studName,rollNum,bookName,dept,fine;
public StudentViewHolder(View itemView) {
super(itemView);
studName=itemView.findViewById(R.id.studentName_prof);
rollNum = itemView.findViewById(R.id.rollNumber_prof);
bookName = itemView.findViewById(R.id.bookName_prof);
fine = itemView.findViewById(R.id.fineAmt_prof);
dept = itemView.findViewById(R.id.department_prof);
}
}
}
and here is my StoreStudentDetails class:
public class storeStudentDetails implements Serializable {
private String studentName;
private String rollNo;
private String book;
private Double fine;
private String dept;
#Exclude private String id;
public storeStudentDetails() {
}
public storeStudentDetails(String studentName, String rollNo,String book, double fine ,String dept) {
this.studentName = studentName;
this.rollNo = rollNo;
this.book = book;
this.fine = fine;
this.dept = dept;
}
public void setId(String id) {
this.id = id;
}
public String getStudentName() {
return studentName;
}
public String getRollNo() {
return rollNo;
}
public String getBook() {
return book;
}
public Double getFine() {
return fine;
}
public String getDept() {
return dept;
}
public String getId() {
return id;
}
}

To solve this, please move the following lines of code:
mStoreDetailsAdapter = new storeDetailsAdapter(this,studentDetailsList);
mRecyclerView.setAdapter(mStoreDetailsAdapter);
Right before the following line of code:
mStoreDetailsAdapter.notifyDataSetChanged();
And this is because onSuccess() method has an asynchronous behavior and by the time you are setting the adapter outside the callback your list is empty.
As you can see, the easiest solution for this problem is to move those lines of code inside the callback. but if you want to use the value of your studentDetailsList outside the onSuccess() method, I recommend you see the last part of my anwser from this post in which I have explained how it can be done using a custom callback. You can also take a look at this video for a better understanding.

iam using Retrofit library to fetch data from Database to recyclerview

am trying to Fetch the movies data from Mysql DB and show it to Recycler view
but when i run the app nothing shows
here is code i am using Retrofite Library
but i can't parse the Data to the Recycler view
i've made Adapter and Model Class normally like the Json
MainActivity.class
public class MainActivity extends AppCompatActivity {
private static final String url="http://192.168.1.109/stu/";
RecyclerView recyclerViewMovies;
List<MovieListsModels> movies;
MoviesAdapter adapter;
TextView Errortxt;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Errortxt = (TextView)findViewById(R.id.txterror);
recyclerViewMovies = (RecyclerView)findViewById(R.id.recyclerview);
recyclerViewMovies.setHasFixedSize(true);
recyclerViewMovies.setLayoutManager(new LinearLayoutManager(this));
movies = new ArrayList<>();
loadDatafromServer();
}
private void loadDatafromServer() {
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(url)
.addConverterFactory(GsonConverterFactory.create())
.build();
Api api = retrofit.create(Api.class);
Call<MovieListsModels> call = api.ShowMoviesData();
call.enqueue(new Callback<MovieListsModels>() {
#Override
public void onResponse(Call<MovieListsModels> call, Response<MovieListsModels> response) {
try {
MovieListsModels movie = response.body();
adapter = new MoviesAdapter(MainActivity.this, (List<MovieListsModels>) movie);
recyclerViewMovies.setAdapter(adapter);
}
catch (Exception e) {
e.printStackTrace();
}
}
#Override
public void onFailure(Call<MovieListsModels> call, Throwable t) {
Errortxt.setText(t.getMessage().toString());
}
});
}
this is the interface of the methods
Api.class Interface
public interface Api {
#GET("config.php")
Call<MovieListsModels> ShowMoviesData();
}
MovieLists.class
public class MovieListsModels {
public MovieListsModels() {
}
int id;
String movie_name;
String movie_image;
String movie_genre;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getMovie_name() {
return movie_name;
}
public void setMovie_name(String movie_name) {
this.movie_name = movie_name;
}
public String getMovie_image() {
return movie_image;
}
public void setMovie_image(String movie_image) {
this.movie_image = movie_image;
}
public String getMovie_genre() {
return movie_genre;
}
public void setMovie_genre(String movie_genre) {
this.movie_genre = movie_genre;
}
public MovieListsModels(int id, String movie_name, String movie_image, String movie_genre) {
this.id = id;
this.movie_name = movie_name;
this.movie_image = movie_image;
this.movie_genre = movie_genre;
}
}
MovieAdapter.class
public class MoviesAdapter extends RecyclerView.Adapter<MoviesAdapter.MovieHolderView> {
private Context mContext;
private List<MovieListsModels> MovieList = new ArrayList<>();
public MoviesAdapter(Context mContext, List<MovieListsModels> movieList) {
this.mContext = mContext;
MovieList = movieList;
}
#NonNull
#Override
public MovieHolderView onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_item,parent,false);
MovieHolderView holder = new MovieHolderView(view);
return holder;
}
#Override
public void onBindViewHolder(#NonNull MovieHolderView holder, int position) {
MovieListsModels list = MovieList.get(position);
holder.txtName.setText(list.getMovie_name());
holder.txtGenre.setText(list.getMovie_genre());
Picasso.get()
.load(list.getMovie_image())
.into(holder.imgMovie);
}
#Override
public int getItemCount() {
return MovieList.size();
}
public class MovieHolderView extends RecyclerView.ViewHolder {
TextView txtName,txtGenre;
ImageView imgMovie;
public MovieHolderView(View itemView) {
super(itemView);
txtName =(TextView)itemView.findViewById(R.id.movieName);
txtGenre =(TextView)itemView.findViewById(R.id.movieGenre);
imgMovie =(ImageView)itemView.findViewById(R.id.movieImg);
}
}
}

If you receive a list of movies is better because you expect a list, I suppose
public void onResponse(Call<MovieListsModels> call, Response<MovieListsModels> response) {
try {
List<MovieListsModels> movie = response.body();
adapter = new MoviesAdapter(MainActivity.this, movies);
And I believe that not executing the notifyDataSetChanged, you can added like that:
private Context mContext;
private List<MovieListsModels> MovieList = new ArrayList<>();
public MoviesAdapter(Context mContext, List<MovieListsModels> movieList) {
this.mContext = mContext;
MovieList = movieList;
notifiyDataSetChanged();

If you are having json response of the form {..}, you are having an object response and you should expect an object as you have done i.e, Call<YourObject>
If you are having json response of the form [..], you are having an array response and you should expect an array i.e, Call<List<YourObject>>
In your case, i hope its an array(second case), So make changes as per the above answer done by #Guillodacosta

First don't forget to add the internet permission in your manifest file
<uses-permission android:name="android.permission.INTERNET" />
Second try this
Picasso.with(mContext).load(list.getMovie_image()).into(holder.imgMovie);

Firebase database load data into Listview

I have this DB structure:
{
"customers" : {
"-L-OcgJ0kwTNSm6HoSvG" : {
"address" : "Test Alamat",
"birthday" : "1990-12-03",
"email" : "Dodi#gmail.com",
"name" : "Dodi",
"outletID" : "2673",
"phone" : "09888777111"
}
}
}
Now i want to load all data of "customers" into ListView using FirebaseUI-Android library. And here is the codes:
Query query = FirebaseDatabase.getInstance().getReference().child("customers").limitToLast(50);
FirebaseListOptions<Customers> options = new FirebaseListOptions.Builder<Customers>()
.setLayout(R.layout.row_customer)
.setQuery(query, Customers.class)
.build();
FirebaseListAdapter<Customers> adapter = new FirebaseListAdapter<Customers>(options) {
#Override
protected void populateView(View view, Customers customer, int position) {
((TextView) view.findViewById(R.id.txtCustomerName)).setText(customer.name);
((TextView) view.findViewById(R.id.txtCustomerAddress)).setText(customer.address);
((TextView) view.findViewById(R.id.txtCustomerPhone)).setText(customer.phone);
//and i've set the adapter into ListView
((ListView)layout.findViewById(R.id.lvCustomerList)).setAdapter(adapter);
And here is Customers.java:
#IgnoreExtraProperties
public class Customers {
public String name, outletID, address, phone, birthday, email;
public Customers() {
}
public Customers(String name, String outletID, String address, String phone, String birthday, String email) {
this.name = name;
this.outletID = outletID;
this.address = address;
this.phone = phone;
this.birthday = birthday;
this.email = email;
}
}
Please help me what is the problem with my source code?
i've run it and the data failed to display (only blank on my listview). There's no errors on my Android Studio logs.

I recommend to you to create custom Adapter and to use a RecyclerView (it is faster and better than a ListView )
Something like this:
public class CustomerAdapter extends RecyclerView.Adapter<CustomerAdapter.MessageViewHolder> {
private List<Customer> customerList;
private Context context;
public CustomerAdapter(List<Customer> customerList, Context context) {
this.customerList= customerList;
this.context = context;
}
#Override
public CustomerAdapter.MessageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.your_layout, parent, false);
return new CustomerAdapter.MessageViewHolder(v);
}
public class CustomerViewHolder extends RecyclerView.ViewHolder {
public TextView customername, customeraddress, customerphone;
public CustomerViewHolder(View view) {
super(view);
customername = view.findViewById(R.id.txtCustomerName);
customeraddress = view.findViewById(R.id.txtCustomerAddress);
customerphone = view.findViewById(R.id.txtCustomerPhone);
}
}
#Override
public int getItemCount() {
return customerList.size();
}
#Override
public void onBindViewHolder(final CustomerAdapter.MessageViewHolder holder, final int position) {
holder.customername.setText(customerList.get(position).getName;
holder.customeraddress.setText(customerList.get(position).getAddress;
holder.customerphone.setText(customerList.get(position).getPhone;
}
And you can get the data like this:
FirebaseDatabase.getInstance().getReference().child("customers").addValueEventListener(new ValueEventlistener{
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
List<Customer> custoemrList = new ArrayList<>();
for (final DataSnapshot snapshot : dataSnapshot.getChildren()) {
Customer customer = new Customer();
customer.setName(snapshot.child("name").getValue().toString();
...
...
customerList.add(customer);
}
customerAdapter= new customerAdapter(customerList, YourActivity.this);
recyclerView.setAdapter(chatsAdapter);
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
});
And in your Customer class you have to add getters and setters.
Press Alt + Insert -> Getters and Setters -> Select All -> Enter
This should be it

Change this line of code:
Query query = FirebaseDatabase.getInstance().getReference().child("customers").limitToLast(50)
with
Query query = FirebaseDatabase.getInstance().getReference()
.child("customers")
.orderByChild("name")
.limitToLast(50);