Firebase Cloud Messaging

Add a Firebase configuration file :

In your root-level (project-level) Gradle file (build.gradle), add rules to include the Google Services Gradle plugin. Check that you have Google's Maven repository, as well.

buildscript {

  repositories {
    // Check that you have the following line (if not, add it):
    google()  // Google's Maven repository
  }

  dependencies {
    // ...

    // Add the following line:
    classpath 'com.google.gms:google-services:4.3.10'  // Google Services plugin
  }
}

allprojects {
  // ...

  repositories {
    // Check that you have the following line (if not, add it):
    google()  // Google's Maven repository
    // ...
  }
}

In your module (app-level) Gradle file (usually app/build.gradle), apply the Google Services Gradle plugin:

apply plugin: 'com.android.application'
// Add the following line:
apply plugin: 'com.google.gms.google-services'  // Google Services plugin

android {
  // ...
}

Add Firebase SDKs to your app :

dependencies {
    // Import the BoM for the Firebase platform
    implementation platform('com.google.firebase:firebase-bom:29.0.0')

    // Declare the dependencies for the Firebase Cloud Messaging and Analytics libraries
    // When using the BoM, you don't specify versions in Firebase library dependencies
    implementation 'com.google.firebase:firebase-messaging'
    implementation 'com.google.firebase:firebase-analytics'
}

Edit your app manifest :

<service
    android:name=".java.MyFirebaseMessagingService"
    android:exported="false">
    <intent-filter>
        <action android:name="com.google.firebase.MESSAGING_EVENT" />
    </intent-filter>
</service>

Notifications for :

 FirebaseMessaging.getInstance().getToken()
                .addOnCompleteListener(new OnCompleteListener<String>() {
                    @Override
                    public void onComplete(@NonNull Task<String> task) {
                        if (!task.isSuccessful()) {
                            Log.w(TAG, "Fetching FCM registration token failed", task.getException());
                            return;
                        }

                        String token = task.getResult();
                        @SuppressLint({"StringFormatInvalid", "LocalSuppress"}) String msg = getString(R.string.app_name, token);
                        Log.d(TAG, msg);
                        Toast.makeText(MainActivity.this, msg, Toast.LENGTH_SHORT).show();
                    }
                });

Topic Message for :

 FirebaseMessaging.getInstance().subscribeToTopic("topicnameadd")
                .addOnCompleteListener(new OnCompleteListener<Void>() {
                    @Override
                    public void onComplete(@NonNull Task<Void> task) {
                        String msg = getString(R.string.app_name);
                        if (!task.isSuccessful()) {
                            msg = getString(R.string.app_name);
                        }
                        Log.d(TAG, msg);
                        Toast.makeText(MainActivity.this, msg, Toast.LENGTH_SHORT).show();
                    }
                });

Json data for example :

 try {
            Map<String, String> params = remoteMessage.getData();
            JSONObject object = new JSONObject(params);
            Log.e("JSON OBJECT", object.toString());
            String image = object.getString("image"); // image --> data name

        } catch (JSONException e) {
            e.printStackTrace();
        }

Screenshots of the app :

📄 Firebase Documents 👉🏼 https://firebase.google.com/docs/cloud-messaging/android/client