How to send notification to a topic in Firebase?

 

Step 1: Set up Firebase Project

 

• Go to the Firebase Console.
• Click on "Add project" to create a new Firebase project.
• Enter the project name and click "Continue."
• Follow the prompts to set up Google Analytics if needed, and then click "Create Project."
• Once the project is created, click "Continue" to navigate to the Firebase dashboard.

 

Step 2: Set Up an Android App in Firebase

 

• In your Firebase project overview, click on the Android icon to add a new app.
• Enter your Android package name (usually found in your AndroidManifest.xml file) and app nickname.
• Click "Register app."
• Download the google-services.json file and place it in your app's app/ directory.

 

Step 3: Configure Your Android Project

 

1. Open your build.gradle (Project level) and add the Firebase and Google services dependencies:

    
   buildscript {
       dependencies {
           // Add this line
           classpath 'com.google.gms:google-services:4.3.10'
       }
   }
   

2. Open your build.gradle (App level) and apply the Google services plugin:

   
   apply plugin: 'com.android.application'
   apply plugin: 'com.google.gms.google-services' 
   

3. Add Firebase Cloud Messaging dependency:

   
   dependencies {
       // Add this line
       implementation 'com.google.firebase:firebase-messaging:23.0.0'
   }
   

 

Step 4: Subscribe to a Topic in Your Android App

 

• In your app's main activity (or wherever appropriate), subscribe to a topic:

  
   import com.google.firebase.messaging.FirebaseMessaging;
  
   public class MainActivity extends AppCompatActivity {
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity\_main);
  
           // Subscribe to a Firebase topic
           FirebaseMessaging.getInstance().subscribeToTopic("news")
                   .addOnCompleteListener(task -> {
                       String msg = "Subscription successful";
                       if (!task.isSuccessful()) {
                           msg = "Subscription failed";
                       }
                       Log.d("FirebaseTopic", msg);
                   });
       }
   }
   

 

Step 5: Send a Notification to a Topic from Firebase Console

 

• Go to the Firebase Console.
• In the left sidebar, click on “Cloud Messaging.”
• Click on “Send your first message.”
• Enter the notification text and other details.
• Click on the “Send to topic” option and enter the name of your topic (e.g., "news").
• Click “Next”, review your message, and finally click “Publish.”

 

Step 6: Handle Notifications in Your App

 

• If your app is in the foreground, messages will not be displayed in the system tray, so you need to handle them manually. Extend FirebaseMessagingService:

  
   import com.google.firebase.messaging.FirebaseMessagingService;
   import com.google.firebase.messaging.RemoteMessage;
  
   public class MyFirebaseMessagingService extends FirebaseMessagingService {
       @Override
       public void onMessageReceived(RemoteMessage remoteMessage) {
           // Handle FCM messages here.
           if (remoteMessage.getNotification() != null) {
               String title = remoteMessage.getNotification().getTitle();
               String body = remoteMessage.getNotification().getBody();
               sendNotification(title, body);
           }
       }
  
       private void sendNotification(String title, String messageBody) {
           NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, CHANNEL\_ID)
                   .setContentTitle(title)
                   .setContentText(messageBody)
                   .setPriority(NotificationCompat.PRIORITY\_HIGH)
                   .setAutoCancel(true)
                   .setSmallIcon(R.drawable.ic\_notification);
  
           NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION\_SERVICE);
           notificationManager.notify(0, notificationBuilder.build());
       }
   }
   

 

Step 7: Test Your Setup

 

• Run your app on a physical device or emulator.
• Make sure the device/emulator has internet access and check the logcat for the subscription success message.
• Use the Firebase console to send a test notification to your topic.
• Verify the notification is received and handled in your app.