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Fetching data using retrofit2 and saving in room

I am using retrofit2 for fetching data from the server and after fetching saving data in room database and then showing in recycler view.Whenever app runs its fetches data from the server and save it in room database.I have successfully fetched JSON data from server and saved in room database and from room it is properly showing in recycler view.
Problem: Whenever data fetches from the server it inserts the same old data in room again due to which same data shows multiple times in recycler view.
What I want: I don't want recycler view to show same data multiple times.I don't want to copy same data again in 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();
}
UserAdapter.java
public class UserAdapter extends
RecyclerView.Adapter<UserAdapter.ViewHolder> {
List<User> userList;
Context context;
public UserAdapter(List<User> userList, Context context) {
this.userList = userList;
this.context = context;
}
#NonNull
#Override
public UserAdapter.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.user_row_layout,parent,false);
ViewHolder viewHolder = new ViewHolder(v);
return viewHolder;
}
#Override
public void onBindViewHolder(#NonNull UserAdapter.ViewHolder holder, int position) {
User users = userList.get(position);
holder.row_name.setText(users.getName());
holder.row_age.setText(users.getAge());
}
#Override
public int getItemCount() {
return userList.size();
}
public void setUserList(List<User> userList) {
this.userList = userList;
notifyDataSetChanged();
}
public class ViewHolder extends RecyclerView.ViewHolder {
TextView row_name,row_age;
public ViewHolder(#NonNull View itemView) {
super(itemView);
row_name = itemView.findViewById(R.id.row_name);
row_age = itemView.findViewById(R.id.row_age);
}
}
}
Someone please let me know how can I achieve desired result. Any help would be appreciated.
THANKS

The answer is quite simple, you do not have a unique primary key. You're generating a key yourself using
String id = UUID.randomUUID().toString();
In your first request, you might have this:
User("mdkasdkasjkdjakjdkasd", "Zun", 22);
and in your second request you get
User("djei3ujf493j9fj49dj9", "Zun", 22);
as such, you'll always have duplicate entries in your database since room considers the user with name 'Zun" to NOT be the same.
In order to solve this, create a unique primary key that's unique to a User class. Do not use a random text generator.

Okay you should do it like this,
check if user is exist in db or not,
#Query("SELECT * FROM user WHERE id = :userId")
public User idUserExists(int userId);
if it does than add update query
#Update
public void updateUser(User user); // keep the model with same user id
else insert the new record
#Insert
public void insertUser(User user); // Model with new user Id

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.

Cast arraylist in recyclerview firebase

I have an array of data which I am retrieving from firebase. I am using a recyclerview to display the data but my adapter is not working correctly.I tried adding the arraylist in the adapter but this is not working.
It is saying the adapter is not attached and I am having a blank activity.
Any help on this ?
Here are my details.
Modal Class
public class Order {
private String ProductId;
private String ProductName;
private String Quantity;
public Order() {
}
public String getProductId() {
return ProductId;
}
public void setProductId(String productId) {
ProductId = productId;
}
public String getProductName() {
return ProductName;
}
public void setProductName(String productName) {
ProductName = productName;
}
public String getQuantity() {
return Quantity;
}
public void setQuantity(String quantity) {
Quantity = quantity;
}
public Order(String productId, String productName, String quantity) {
ProductId = productId;
ProductName = productName;
Quantity = quantity;
}
}
Adapter
public class AllOrdersAdapter extends RecyclerView.Adapter<AllOrdersViewHolder> {
List<Order> myfoods;
public AllOrdersAdapter(List<Order> myfoods) {
this.myfoods = myfoods;
}
#NonNull
#Override
public AllOrdersViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.allorders_layout,parent,false);
return new AllOrdersViewHolder(itemView);
}
#Override
public void onBindViewHolder(#NonNull AllOrdersViewHolder holder, int position) {
holder.foodname.setText(myfoods.get(position).getProductName());
holder.foodquantity.setText(myfoods.get(position).getQuantity());
holder.foodId.setText(myfoods.get(position).getProductId());
}
#Override
public int getItemCount() {
return myfoods.size();
}
}
Test Class
public class Test extends AppCompatActivity {
FirebaseDatabase db;
DatabaseReference requests;
RecyclerView lstFoods;
RecyclerView.LayoutManager layoutManager;
TextView food_id,food_quan,food_name;
// List foods = new ArrayList<>();
// RecyclerView.Adapter<AllOrder> adapter;
// List<String> myOrders = new ArrayList<String>();
// ArrayList<String> foods=new ArrayList<>();
List<String> myfoods = new ArrayList<String>();
AllOrdersAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test);
//firebase
db = FirebaseDatabase.getInstance();
requests= db.getReference().child("Requests");
lstFoods = (RecyclerView)findViewById(R.id.lstAllFoods);
lstFoods.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(this);
lstFoods.setLayoutManager(layoutManager);
loadOrderss();
}
private void loadOrderss() {
requests.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
if (postSnapshot.getValue() != null) {
// List ingredients = new ArrayList<>();
for (DataSnapshot ing : postSnapshot.child("foods").getChildren()) {
// String data = String.valueOf(postSnapshot.getValue(Order.class));
myfoods.add(ing.child("quantity").getValue(String.class));
myfoods.add(ing.child("productName").getValue(String.class));
myfoods.add(ing.child("productId").getValue(String.class));
// myfoods.add(String.valueOf(Order.class));
System.out.println("Gained data: " + ing.child("productName").getValue(String.class));
}
}
}
adapter = new AllOrdersAdapter((ArrayList<String>) myfoods);
lstFoods.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}

There seems to be a couple things wrong with the code. As it is posted I would be surprised if it compiles.
In your Adapter you have:
List<Order> myfoods;
and
public AllOrdersAdapter(List<Order> myfoods) {
this.myfoods = myfoods;
}
but in your activity code you pass:
adapter = new AllOrdersAdapter((ArrayList<String>) myfoods);
one is a ArrayList of String the other of Order !
You also need to change your adapter class to something like:
public class AllOrdersAdapter extends RecyclerView.Adapter<AllOrdersAdapter.AllOrdersViewHolder> {
private static final String TAG = AllOrdersAdapter.class.getSimpleName();
private ArrayList<Order> mData;
public class AllOrdersViewHolder extends RecyclerView.ViewHolder {
public TextView mTvFoodname;
public TextView mTvFoodQuantity;
public TextView mTvFoodId;
public AllOrdersViewHolder(View v){
super(v);
// TODO: You need to assign the appropriate View Id's instead of the placeholders ????
mTvFoodQuantity = v.findViewById(R.id.????);
mTvFoodname = v.findViewById(R.id.????);
mTvFoodId = v.findViewById(R.id.????);
}
}
public AllOrdersAdapter(ArrayList<Order> data){
this.mData = data;
}
#Override
public AllOrdersViewHolder onCreateViewHolder(ViewGroup parent, int viewType){
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.business_list_card_view, parent, false);
return new AllOrdersViewHolder(itemView);
}
#Override
public void onBindViewHolder(final AllOrdersViewHolder holder, final int position){
//TODO: You need to decide whether you want to pass a string or order object
Order data = mData.get(position);
final String name = data.getProductName();
final String quantity = data.getQuantity();
final String id = data.getProductId();
holder.mTvFoodname.setText(name);
holder.mTvFoodQuantity.setText(quantity );
holder.mTvFoodId.setText(id)
}
#Override
public int getItemCount(){
return mData.size();
}
}
Note: That since I can not know, whether an ArrayList of String or of Order should be used the parameters in either the Activity or Adapter will need to be changed. Also how you assign the data to the RecyclerView will be affected in the onBindViewHolder method.
You should also follow the advice given by Frank.
EDIT
Change your onDataChange() method to this:
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
if (postSnapshot.getValue() != null) {
List ingredients = new ArrayList<>();
for (DataSnapshot ing : postSnapshot.child("foods").getChildren()) {
String name = ing.child("productName").getValue(String.class);
String quantity = ing.child("quantity").getValue(String.class);
String productId = ing.child("productId").getValue(String.class);
// Using your overloaded class constructor to populate the Order data
Order order = new Order(productId, name, quantity);
// here we are adding the order to the ArrayList
myfoods.add(order);
Log.e(TAG, "Gained data: " + name)
}
}
}
adapter.notifyDataSetChanged();
}
In your Activity you will need to change the ArrayList class variable "myfoods" to this:
ArrayList(Order) myfoods = new ArrayList<>();
and in your onCreate() method you can now change:
adapter = new AllOrdersAdapter((ArrayList<String>) myfoods);
to simply this:
adapter = new AllOrdersAdapter(myfoods);
Also notice that I have made some changes in my original code above.

You'll want to create the adapter, and attach it to the view, straight in onCreate:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test);
//firebase
db = FirebaseDatabase.getInstance();
requests= db.getReference().child("Requests");
lstFoods = (RecyclerView)findViewById(R.id.lstAllFoods);
lstFoods.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(this);
lstFoods.setLayoutManager(layoutManager);
adapter = new AllOrdersAdapter((ArrayList<String>) myfoods);
lstFoods.setAdapter(adapter);
loadOrders();
}
This also means you should declare myfoods as a ArrayList<String>, which saves you from having to downcast it. Something like:
ArrayList<String> myfoods = new ArrayList<String>();
Now in loadOrders you simple add the items to the list, and then notify the adapter that its data has changed (so that it repaints the view):
private void loadOrders() {
requests.child("foods").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
for (DataSnapshot ing: postSnapshot.getChildren()) {
myfoods.add(ing.child("quantity").getValue(String.class));
myfoods.add(ing.child("productName").getValue(String.class));
myfoods.add(ing.child("productId").getValue(String.class));
}
}
adapter.notifyDataSetChanged();
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
throw databaseError.toException(); // don't ignore errors
}
});
}

Populating RecyclerView with data from Firebase Database

I created a RecyclerView with data loaded locally using a standard model and adapter approach, the views that the RecyclerView recycles hold an image and 3 text views. I'd like to populate these views using data from a Firebase Database. I've created the data on Firebase which looks like this:
{
"items" : {
"item 1" : {
"colour-value" : "000000",
"manufacturer" : "Manufacturer 1",
"name" : "Name 1",
"type" : "Type 1"
},
"item 2" : {
"colour-value" : "ffff00",
"manufacturer" : "Manufacturer 2",
"name" : "Name 2",
"type" : "Type 2"
},
"item 3" : {
"colour-value" : "ff0000",
"manufacturer" : "Manufacturer 3",
"name" : "Name 3",
"type" : "Type 3"
}
}
}
I've already added the dependencies and have Firebase Auth set up and working. The data will never be changed by the user but may be changed manually in the back end from time to time. The image is a single white png with the colour changed based on the colour-value.
Everything that I've seen appears to be overly complex for what I need and I'm convinced it doesn't need to be but can't whittle down what I need to feed this data into the RecyclerView.
Any pointers? Thanks.
EDIT - All special characters have been removed from data.
ItemAdapter
public class ItemAdapter extends
RecyclerView.Adapter<ItemAdapter.MyViewHolder> {
private Context mContext;
private List<Item> itemList;
class MyViewHolder extends RecyclerView.ViewHolder {
TextView itemName, itemManufacturer, itemType;
private MyViewHolder (View view) {
super(view);
itemName = view.findViewById(R.id.item_name);
itemManufacturer = view.findViewById(R.id.item_manufacturer);
itemType = view.findViewById(R.id.item_type);
}
}
ItemAdapter(Context mContext, List<Item> itemList) {
this.mContext = mContext;
this.itemList = itemList;
}
#Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item, parent, false);
return new MyViewHolder(itemView);
}
#Override
public void onBindViewHolder(final Item.MyViewHolder holder, int position) {
Item item = itemList.get(position);
holder.itemName.setText(item.getItemName());
holder.itemManufacturer.setText(item.getItemManufacturer());
holder.itemType.setText(item.getItemType());
}
void filter (ArrayList<Item> newList) {
itemList = new ArrayList<>();
itemList.addAll(newList);
notifyDataSetChanged();
}
#Override
public int getItemCount() {
return itemList.size();
}
}

The first problem here in your JSON you can not have a hyphen or spaces in your keys as firebase will do a mapping based on keys to POJO member variables and java does not allow special characters in namings.
So if you change your keys just do this
Make a POJO
public class SampleModel {
private int colorValue;
private String manufacturer;
private String name;
private String type;
public int getColorValue() {
return colorValue;
}
public void setColorValue(int colorValue) {
this.colorValue = colorValue;
}
public String getManufacturer() {
return manufacturer;
}
public void setManufacturer(String manufacturer) {
this.manufacturer = manufacturer;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
}
then create your database reference and get the data and update the list
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
DatabaseReference myRef = FirebaseDatabase.getInstance().getReference("items");
myRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
//you have data now traverse
for (DataSnapshot child: dataSnapshot.getChildren()){
//your data may come up in map so handle here
HashMap<String,SampleModel> hashMap = (HashMap<String,SampleModel>)child.getValue();
//if everything is okay then just iterate over the map and create a list
List<SampleModel> sampleModels = new ArrayList<>()
for (HashMap.Entry<String,SampleModel> modelEntry:hashMap.entrySet()){
sampleModels.add(modelEntry.getValue());
}
mainList.addAll(sampleModels);
adapter.notifyDataSetChanged();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
//for some reason data did't show up
}
});
Edit: Added
HashMap<String,SampleModel> hashMap = (HashMap<String,SampleModel>)child.getValue();

Android Firebase Database Adding items with keys to recycler view

I was trying to add & show messages dynamically in recycler view but I could not figure out how to send proper data type to it's adapter. In "getNewMessage(dataSnapshot) " function, I have to add all messages to list and send it to recycler view via adapter. I tried both
MessageModel model = dataSnapshot.getValue(MessageModel.class)
and creating a SampleModel that contains List<MessageModel> list, and
SampleModel model = dataSnapshot.getValue(SampleModel.class);
They didn't work. Here sample JSON file that created with sending message:
"chat" : {
"-Ksbjn0yCEB6EXhNNCM5" : {
"author" : "Ali Alacan",
"content" : "dummy content",
"date" : "Mon Aug 28 10:29:50 GMT+03:00 2017",
"id" : "H6huNPUggjtugjsERPCRSAp1"
},
"-KsbjpUtjp0oeipjjxMI" : {
"author" : "Ali Alacan",
"content" : "dummy content",
"date" : "Mon Aug 28 10:30:00 GMT+03:00 2017",
"id" : "H6huNPUggjtugjsERPCRSAp1"
}
I'm adding new messages with code below which I learnt from firebase docs.
#Exclude
public Map<String, Object> toMap(MessageModel messageModel) {
HashMap<String, Object> result = new HashMap<>();
result.put("id", messageModel.getId());
result.put("author", messageModel.getAuthor());
result.put("content", messageModel.getContent());
result.put("date", messageModel.getDate());
return result;
}
private void sendMessage() {
if (!TextUtils.isEmpty(etMessage.getText())) {
Date currentTime = Calendar.getInstance().getTime();
String key = firebaseDatabase.push().getKey();
MessageModel message = new MessageModel(UserData.getInstance().getUserId(), UserData.getInstance().getName(), "dummy content", currentTime.toString());
Map<String, Object> messageValues = toMap(message);
Map<String, Object> childUpdates = new HashMap<>();
childUpdates.put("/chat/" + key, messageValues);
childUpdates.put("/user-chat/" + UserData.getInstance().getUserId() + "/" + key, messageValues);
firebaseDatabase.updateChildren(childUpdates);
} else {
Snackbar snackbar = Snackbar
.make(getActivity().findViewById(R.id.dashboard_container), "Enter a message please ! " + UserData.getInstance().getName(), Snackbar.LENGTH_LONG);
snackbar.show();
}
}
My MessageModel is:
public class MessageModel {
String id;
String author;
String content;
String date;
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
public MessageModel(String id, String author, String content, String date) {
this.id = id;
this.author = author;
this.content = content;
this.date = date;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public MessageModel() {
}
}
And firebase listener
firebaseDatabase.addChildEventListener(new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
getNewMessage(dataSnapshot);
}
#Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
// getNewMessage(dataSnapshot);
}
#Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
// taskDeletion(dataSnapshot);
}
#Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
RecyclerView Adapter:
public class MyMessageRecyclerViewAdapter extends RecyclerView.Adapter<MyMessageRecyclerViewAdapter.ViewHolder> {
private final List<MessageModel> mValues;
private final OnListFragmentInteractionListener mListener;
public MyMessageRecyclerViewAdapter(List<MessageModel> items, OnListFragmentInteractionListener listener) {
mValues = items;
mListener = listener;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_chat, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(final ViewHolder holder, int position) {
holder.mItem = mValues.get(position);
holder.mIdView.setText(mValues.get(position).getId());
holder.mContentView.setText(mValues.get(position).getContent());
holder.mAuthor.setText(mValues.get(position).getAuthor());
holder.mDate.setText(mValues.get(position).getDate());
holder.mView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (null != mListener) {
// Notify the active callbacks interface (the activity, if the
// fragment is attached to one) that an item has been selected.
mListener.onListFragmentInteraction(holder.mItem);
}
}
});
}
#Override
public int getItemCount() {
return mValues.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
public final View mView;
public final TextView mIdView;
public final TextView mContentView;
TextView mAuthor;
TextView mDate;
public MessageModel mItem;
public ViewHolder(View view) {
super(view);
mView = view;
mIdView = (TextView) view.findViewById(R.id.id);
mContentView = (TextView) view.findViewById(R.id.content);
mAuthor = (TextView) view.findViewById(R.id.author);
mDate = (TextView) view.findViewById(R.id.date);
}
#Override
public String toString() {
return super.toString() + " '" + mContentView.getText() + "'";
}
}
Sorry for reading such a long post and thank you for your time.

You don't need to use your toMap anymore, it is making you more confused on what you're doing since You already have a POJO.
Make a List in your Activity.
ArrayList<MessageModel> myListModel = new ArrayList<MessageModel>();
Do this on your firebase Listener. Make a List on your Activity
This is for Child Added.
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
MessageModel tempMessage = dataSnapshot.getValue(MessageModel.class);
myListModel.add(tempRace);
}
Now That you have a List Model. By using the onChildAdeed by Firebase.
Use this to your supply your Adapter Model and apply it.
IMPORTANT FOR FIREBASE. In everyquery for the fire base, if you need to do something AFTER the anything else is done ex: "onChildAdded" You would need to add another listener to THE SAME DatabaseReference in your case. I have no idea, you did not include your activity even your DatabaseReference so I would provide one.
DatabaseReference myReference = firebaseDatabase.getReferane("chat");
myReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
MyMessageRecyclerAdapter myMessageAdapter= new MyMessageRecyclerAdapter(myListModel, listener);
//now you have to apply this to the RecyclerView.
yourWhateverNameofTheRecyclerview.SetAdapter(myMessageAdater);
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});