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OnMessageReceived(RemoteMessage RemoteMessage) Firebase Chat Null Error When Using Fcm For Notification

I am now following the creation of a firebase based chat on YouTube.

If you receive a chat message using firebase's FCM,

In the lecture, using Retrofit2 Send data to the server as a JSON Object

But

 @Override
    public void onMessageReceived (RemoteMessage remoteMessage) {
        super.onMessageReceived (remoteMessage);

        String sented = remoteMessage.getData (). Get ("sented");

        FirebaseUser firebaseUser = FirebaseAuth.getInstance (). GetCurrentUser ();

        if (firebaseUser! = null && sented.equals (firebaseUser.getUid ())) {
            sendNotification (remoteMessage);
        }
    }

in this part i can see that sented is null. So it seems to be an error.

When I read YouTube comments, there are many people who are having the same problem There seems to be no one who knows what is causing the problem.

I can not understand why sented is null, and I want to know how remoteMessage calls a value named sented

How can I solve this problem?

This is my error

2019-07-11 19:19:07.488 12281-12457/com.example.blogapp E/AndroidRuntime: FATAL EXCEPTION: Firebase-MyFirebaseMessaging
    Process: com.example.blogapp, PID: 12281
    java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
        at com.example.together.notification.MyFirebaseMessaging.onMessageReceived(MyFirebaseMessaging.java:31)
        at com.google.firebase.messaging.FirebaseMessagingService.zzc(com.google.firebase:[email protected]@19.0.1:67)
        at com.google.firebase.messaging.zzg.run(com.google.firebase:[email protected]@19.0.1:2)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
        at com.google.android.gms.common.util.concurrent.zza.run(Unknown Source:6)
        at java.lang.Thread.run(Thread.java:764)

This is MyFirebaseMessaging.class

package com.example.together.notification;

import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.Bundle;


import androidx.core.app.NotificationCompat;

import com.example.together.activities.chat.MessageActivity;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.messaging.FirebaseMessagingService;
import com.google.firebase.messaging.RemoteMessage;

public class MyFirebaseMessaging extends FirebaseMessagingService {

    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        super.onMessageReceived(remoteMessage);

        String sented = remoteMessage.getData().get("sented");

        FirebaseUser firebaseUser = FirebaseAuth.getInstance().getCurrentUser();

        if (firebaseUser != null && sented.equals(firebaseUser.getUid())){
            sendNotification(remoteMessage);
        }
    }

    private void sendNotification(RemoteMessage remoteMessage) {

        String user = remoteMessage.getData().get("user");
        String icon = remoteMessage.getData().get("icon");
        String title = remoteMessage.getData().get("title");
        String body = remoteMessage.getData().get("body");

        RemoteMessage.Notification notification = remoteMessage.getNotification();
        int j = Integer.parseInt(user.replaceAll("[\\D]",""));
        Intent intent = new Intent(this, MessageActivity.class);
        Bundle bundle = new Bundle();
        bundle.putString("userid", user);
        intent.putExtras(bundle);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, j, intent, PendingIntent.FLAG_ONE_SHOT);

        Uri defaultSound = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder builder = new NotificationCompat.Builder(this)
                .setSmallIcon(Integer.parseInt(icon))
                .setContentTitle(title)
                .setContentText(body)
                .setAutoCancel(true)
                .setSound(defaultSound)
                .setContentIntent(pendingIntent);

        NotificationManager noti = (NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);

        int i = 0;

        if (j > 0){
            i = j;
        }

        noti.notify(i, builder.build());


    }
}

Client.class

package com.example.together.notification;

import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class Client {

    private static Retrofit retrofit = null;

    public static Retrofit getClient(String url){
        if (retrofit == null){
            retrofit = new Retrofit.Builder()
                    .baseUrl(url)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
        }
        return retrofit;
    }
}

MyFirebaseIdService.class

package com.example.together.notification;

import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.iid.FirebaseInstanceId;
import com.google.firebase.messaging.FirebaseMessagingService;

public class MyFirebaseIdService extends FirebaseMessagingService {

    @Override
    public void onNewToken(String s) {
        super.onNewToken(s);
        FirebaseUser firebaseUser = FirebaseAuth.getInstance().getCurrentUser();

        String refreshToken = FirebaseInstanceId.getInstance().getToken();
        if (firebaseUser != null){
            updateToke(refreshToken);
        }
    }

    private void updateToke(String refreshToken) {
        FirebaseUser firebaseUser = FirebaseAuth.getInstance().getCurrentUser();

        DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Tokens");
        Token token = new Token(refreshToken);
        reference.child(firebaseUser.getUid()).setValue(token);
    }
}

This is Data.class

package com.example.together.notification;

public class Data {
    private String user;
    private int icon;
    private String body;
    private String title;
    private String sented;

    public Data(String user, int icon, String body, String title, String sented) {
        this.user = user;
        this.icon = icon;
        this.body = body;
        this.title = title;
        this.sented = sented;
    }

    public Data() {
    }

    public String getUser() {
        return user;
    }

    public void setUser(String user) {
        this.user = user;
    }

    public int getIcon() {
        return icon;
    }

    public void setIcon(int icon) {
        this.icon = icon;
    }

    public String getBody() {
        return body;
    }

    public void setBody(String body) {
        this.body = body;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getSented() {
        return sented;
    }

    public void setSented(String sented) {
        this.sented = sented;
    }
}

This is my Sender.class

package com.example.together.notification;

public class Sender {
    public Data data;
    public String to;

    public Sender(Data data, String to) {
        this.data = data;
        this.to = to;
    }
}

API Service interface

package com.example.together.fragment;

import com.example.together.notification.MyResponse;
import com.example.together.notification.Sender;

import retrofit2.Call;
import retrofit2.http.Body;
import retrofit2.http.Headers;
import retrofit2.http.POST;

public interface APIService {
    @Headers(
            {
                    "Content-Type:application/json",
                    "Authorization:key=MyKeyValue"
            }

    )

    @POST("fcm/send")
    Call<MyResponse> sendNotification(@Body Sender body);

}

This is my MessageActivity

package com.example.together.activities.chat;

import android.content.Intent;

import android.os.Bundle;

import android.view.View;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.TextView;
import android.widget.Toast;


import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.bumptech.glide.Glide;
import com.example.together.activities.HomeActivity;
import com.example.together.activities.LoginActivity;
import com.example.together.adapter.MessageAdapter;
import com.example.together.fragment.APIService;
import com.example.together.model.Chat;
import com.example.together.model.User;
import com.example.together.R;
import com.example.together.notification.Client;
import com.example.together.notification.Data;
import com.example.together.notification.MyResponse;
import com.example.together.notification.Sender;
import com.example.together.notification.Token;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
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 java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import de.hdodenhof.circleimageview.CircleImageView;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;

public class MessageActivity extends AppCompatActivity {

    private static final String TAG = "MessageActivity";

    CircleImageView image_profile;
    TextView username;

    FirebaseUser fuser;
    DatabaseReference reference;

    ImageButton btn_send;
    EditText text_send;

    Intent intent;

    MessageAdapter messageAdapter;
    List<Chat> mchat;

    RecyclerView recyclerView;

    ValueEventListener seenListener;

    String userid;

    APIService apiService;

    boolean notify = false;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_message);

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setTitle("");
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        toolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(MessageActivity.this, LoginActivity.class).setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP));
            }
        });

        apiService = Client.getClient("https://fcm.googleapis.com/").create(APIService.class);

        recyclerView = findViewById(R.id.recycler_view);
        recyclerView.setHasFixedSize(true);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getApplicationContext());
        linearLayoutManager.setStackFromEnd(true);
        recyclerView.setLayoutManager(linearLayoutManager);


        image_profile = findViewById(R.id.image_profile);
        username = findViewById(R.id.username);
        btn_send = findViewById(R.id.btn_send);
        text_send = findViewById(R.id.text_send);

        intent = getIntent();
        final String userid = intent.getStringExtra("userid");


        btn_send.setOnClickListener(v -> {
            notify = true;
            String msg = text_send.getText().toString();
            if (!msg.equals("")){
                sendMessage(fuser.getUid(), userid, msg);
            }else {
                Toast.makeText(MessageActivity.this, "내용을 입력해주세요", Toast.LENGTH_SHORT).show();
            }
            text_send.setText("");
        });

        fuser = FirebaseAuth.getInstance().getCurrentUser();
        reference = FirebaseDatabase.getInstance().getReference("Users").child(userid);

        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                User user = dataSnapshot.getValue(User.class);
                username.setText(user.getUsername());
                if (user.getImageurl().equals("default")){
                    image_profile.setImageResource(R.mipmap.ic_launcher);

                }else {
                    Glide.with(getApplicationContext()).load(user.getImageurl()).into(image_profile);
                }


                readMessages(fuser.getUid(), userid, user.getImageurl());

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });

        seenMessage(userid);
    }

    private void seenMessage(String userid){
        reference = FirebaseDatabase.getInstance().getReference("Chats");
        seenListener = reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                for (DataSnapshot snapshot : dataSnapshot.getChildren()){
                    Chat chat = snapshot.getValue(Chat.class);
                    if (chat.getReceiver().equals(fuser.getUid()) && chat.getSender().equals(userid)){
                        HashMap<String , Object> hashMap = new HashMap<>();
                        hashMap.put("isseen", true);
                        snapshot.getRef().updateChildren(hashMap);
                    }
                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
    }



    private void sendMessage(String sender,  String receiver, String message){

        DatabaseReference reference = FirebaseDatabase.getInstance().getReference();

        HashMap<String, Object> hashMap = new HashMap<>();
        hashMap.put("sender", sender);
        hashMap.put("receiver", receiver);
        hashMap.put("message", message);
        hashMap.put("isseen", false);

        reference.child("Chats").push().setValue(hashMap);

        final String msg = message;

        reference = FirebaseDatabase.getInstance().getReference("Users").child(fuser.getUid());
        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                User user = dataSnapshot.getValue(User.class);
                if (notify) {
                    sendNotification(receiver, user.getUsername(), msg);
                }
                notify = false;
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });

    }


    private void sendNotification(String receiver, final String username, final String message){
        DatabaseReference tokens = FirebaseDatabase.getInstance().getReference("Tokens");
        Query query = tokens.orderByKey().equalTo(receiver);
        query.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                for (DataSnapshot snapshot : dataSnapshot.getChildren()){
                    Token token = snapshot.getValue(Token.class);
                    Data data = new Data(fuser.getUid(), R.mipmap.ic_launcher, username+": "+message, "새로운 메시지", userid);

                    Sender sender = new Sender(data, token.getToken());

                    apiService.sendNotification(sender)
                            .enqueue(new Callback<MyResponse>() {
                                @Override
                                public void onResponse(Call<MyResponse> call, Response<MyResponse> response) {
                                    if (response.code() == 200){
                                        if (response.body().success == 1){
                                            Toast.makeText(MessageActivity.this, "Failed", Toast.LENGTH_SHORT).show();
                                        }
                                    }
                                }

                                @Override
                                public void onFailure(Call<MyResponse> call, Throwable t) {

                                }
                            });
                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
    }



    private void readMessages(final String myid, final String userid, final String imageurl){
        mchat = new ArrayList<>();

        reference = FirebaseDatabase.getInstance().getReference("Chats");
        reference.addValueEventListener(new ValueEventListener() {

            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                mchat.clear();
                for (DataSnapshot snapshot : dataSnapshot.getChildren()){
                    Chat chat = snapshot.getValue(Chat.class);
                    if (chat.getReceiver().equals(myid) && chat.getSender().equals(userid) ||
                            chat.getReceiver().equals(userid) && chat.getSender().equals(myid)){
                        mchat.add(chat);
                    }

                    messageAdapter = new MessageAdapter(MessageActivity.this, mchat, imageurl);
                    recyclerView.setAdapter(messageAdapter);
                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {


            }
        });
    }

    @Override
    protected void onPause(){
        super.onPause();
        reference.removeEventListener(seenListener);
    }

}

I want to solve the cause of the problem

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Answer

try inside

@Override
public void onMessageReceived (RemoteMessage remoteMessage) {
        super.onMessageReceived (remoteMessage);
}

this

 Map<String, String> data_notify= remoteMessagedata.getNotification().getBody()

or

Map<String, String> data_notify= remoteMessagedata.getData().get("body")

or

Map<String, String> data_notify =remoteMessagedata.getData()
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source: stackoverflow.com
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