Set up a Firebase Cloud Messaging client app on Android

To write your Firebase Cloud Messaging Android client app, use the FirebaseMessaging API and Android Studio 1.4 or higher with Gradle. The instructions in this page assume that you have completed the steps for adding Firebase to your Android project.

FCM clients require devices running Android 4.1 or higher that also have the Google Play Store app installed, or an emulator running Android 4.1 with Google APIs. Note that you are not limited to deploying your Android apps through Google Play Store.

Set up Firebase and the FCM SDK

1. If you haven't already, add Firebase to your Android project.

2. In Android Studio, add the FCM dependency to your app-level build.gradle file:

   implementation 'com.google.firebase:firebase-messaging:17.3.4'
   

Edit your app manifest

Add the following to your app's manifest:

• A service that extends FirebaseMessagingService. This is required if you want to do any message handling beyond receiving notifications on apps in the background. To receive notifications in foregrounded apps, to receive data payload, to send upstream messages, and so on, you must extend this service.

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

• (Optional) Within the application component, metadata elements to set a default notification icon and color. Android uses these values whenever incoming messages do not explicitly set icon or color.

<!-- Set custom default icon. This is used when no icon is set for incoming notification messages.
     See README(https://goo.gl/l4GJaQ) for more. -->
<meta-data
    android:name="com.google.firebase.messaging.default_notification_icon"
    android:resource="@drawable/ic_stat_ic_notification" />
<!-- Set color used with incoming notification messages. This is used when no color is set for the incoming
     notification message. See README(https://goo.gl/6BKBk7) for more. -->
<meta-data
    android:name="com.google.firebase.messaging.default_notification_color"
    android:resource="@color/colorAccent" />
AndroidManifest.xml

• (Optional) From Android 8.0 (API level 26) and higher, notification channels are supported and recommended. FCM provides a default notification channel with basic settings. If you prefer to create and use your own default channel, set default_notification_channel_id to the ID of your notification channel object as shown; FCM will use this value whenever incoming messages do not explicitly set a notification channel. To learn more, see Manage notification channels.

<meta-data
    android:name="com.google.firebase.messaging.default_notification_channel_id"
    android:value="@string/default_notification_channel_id" />
AndroidManifest.xml

Access the device registration token

On initial startup of your app, the FCM SDK generates a registration token for the client app instance. If you want to target single devices or create device groups, you'll need to access this token by extending FirebaseMessagingService and overriding onNewToken.

This section describes how to retrieve the token and how to monitor changes to the token. Because the token could be rotated after initial startup, you are strongly recommended to retrieve the latest updated registration token.

The registration token may change when:

• The app deletes Instance ID
• The app is restored on a new device
• The user uninstalls/reinstall the app
• The user clears app data.

Retrieve the current registration token

When you need to retrieve the current token, call FirebaseInstanceId.getInstance().getInstanceId() as shown here.

Monitor token generation

The onNewToken callback fires whenever a new token is generated.

/**
 * Called if InstanceID token is updated. This may occur if the security of
 * the previous token had been compromised. Note that this is called when the InstanceID token
 * is initially generated so this is where you would retrieve the token.
 */
@Override
public void onNewToken(String token) {
    Log.d(TAG, "Refreshed token: " + token);

    // If you want to send messages to this application instance or
    // manage this apps subscriptions on the server side, send the
    // Instance ID token to your app server.
    sendRegistrationToServer(token);
}
MyFirebaseMessagingService.java

/**
 * Called if InstanceID token is updated. This may occur if the security of
 * the previous token had been compromised. Note that this is called when the InstanceID token
 * is initially generated so this is where you would retrieve the token.
 */
override fun onNewToken(token: String?) {
    Log.d(TAG, "Refreshed token: $token")

    // If you want to send messages to this application instance or
    // manage this apps subscriptions on the server side, send the
    // Instance ID token to your app server.
    sendRegistrationToServer(token)
}
MyFirebaseMessagingService.kt

After you've obtained the token, you can send it to your app server and store it using your preferred method. See the Instance ID API reference for full detail on the API.

Check for Google Play services

Apps that rely on the Play Services SDK should always check the device for a compatible Google Play services APK before accessing Google Play services features. It is recommended to do this in two places: in the main activity's onCreate() method, and in its onResume() method. The check in onCreate() ensures that the app can't be used without a successful check. The check in onResume() ensures that if the user returns to the running app through some other means, such as through the back button, the check is still performed.

If the device doesn't have a compatible version of Google Play services, your app can call GoogleApiAvailability.makeGooglePlayServicesAvailable() to allow users to download Google Play services from the Play Store.

Prevent auto initialization

Firebase generates an Instance ID, which FCM uses to generate a registration token and Analytics uses for data collection. When an Instance ID is generated, the library will upload the identifier and configuration data to Firebase. If you prefer to prevent Instance ID autogeneration, disable auto initialization for FCM and Analytics (you must disable both) by adding these metadata values to your AndroidManifest.xml:

<meta-data
    android:name="firebase_messaging_auto_init_enabled"
    android:value="false" />
<meta-data
    android:name="firebase_analytics_collection_enabled"
    android:value="false" />
AndroidManifest.xml

To re-enable FCM, make a runtime call:

FirebaseMessaging.getInstance().setAutoInitEnabled(true);
MainActivity.java

FirebaseMessaging.getInstance().isAutoInitEnabled = true
MainActivity.kt

Next steps

After the client app is set up, you are ready to start sending downstream messages with the Notifications composer. This functionality is demonstrated in the quickstart sample, which you can download, run, and review.

To add other, more advanced behavior to your app, you can declare an intent filter and implement an activity to respond to incoming messages. For details, see the guides for sending messages from an app server:

• Send topic messages
• Send to device groups
• Send upstream messages

Keep in mind that, to take advantage of these features, you'll need a server implementation and the server procotols (HTTP or XMPP), or an implementation of the Admin SDK.