Send a test message to a backgrounded app

To get started with FCM, build out the simplest use case: sending a test notification message from the Notifications composer to a development device when the app is in the background on the device. This page lists all the steps to achieve this, from setup to verification — it may cover steps you already completed if you have set up an Android client app for FCM.

Set up the SDK

This section covers tasks you may have completed if you have already enabled other Firebase features for your app.

Before you begin

• Install or update Android Studio to its latest version.

• Make sure that your project meets these requirements:

  • Targets API level 16 (Jelly Bean) or later
  • Uses Gradle 4.1 or later
  • Uses Jetpack (AndroidX), which includes meeting these version requirements:
    • com.android.tools.build:gradle v3.2.1 or later
    • compileSdkVersion 28 or later

• Set up a physical device or use an emulator to run your app.
  Emulators must use an emulator image with Google Play.

• Sign into Firebase using your Google account.

If you don't already have an Android project and just want to try out a Firebase product, you can download one of our quickstart samples.

Create a Firebase project

Before you can add Firebase to your Android app, you need to create a Firebase project to connect to your Android app. Visit Understand Firebase Projects to learn more about Firebase projects.

Register your app with Firebase

After you have a Firebase project, you can add your Android app to it.

Visit Understand Firebase Projects to learn more about best practices and considerations for adding apps to a Firebase project, including how to handle multiple build variants.

1. Go to the Firebase console.

2. In the center of the project overview page, click the Android icon (plat_android) to launch the setup workflow.

   If you've already added an app to your Firebase project, click Add app to display the platform options.

3. Enter your app's package name in the Android package name field.

   What's a package name, and where do you find it?

   • A package name uniquely identifies your app on the device and in the Google Play Store.

   • A package name is often referred to as an application ID.

   • Find your app's package name in your module (app-level) Gradle file, usually app/build.gradle (example package name: com.yourcompany.yourproject).

   • Be aware that the package name value is case-sensitive, and it cannot be changed for this Firebase Android app after it's registered with your Firebase project.

4. (Optional) Enter other app information: App nickname and Debug signing certificate SHA-1.

   How are the App nickname and the Debug signing certificate SHA-1 used within Firebase?

   • App nickname: An internal, convenience identifier that is only visible to you in the Firebase console

   • Debug signing certificate SHA-1: A SHA-1 hash is required by Firebase Authentication (when using Google Sign In or phone number sign in) and Firebase Dynamic Links.

5. Click Register app.

Add a Firebase configuration file

1. Add the Firebase Android configuration file to your app:

   1. Click Download google-services.json to obtain your Firebase Android config file (google-services.json).

   2. Move your config file into the module (app-level) directory of your app.

   What do you need to know about this config file?

   • The Firebase config file contains unique, but non-secret identifiers for your project. To learn more about this config file, visit Understand Firebase Projects.

   • You can download your Firebase config file again at any time.

   • Make sure the config file name is not appended with additional characters, like (2).

2. To enable Firebase products in your app, add the google-services plugin to your Gradle files.

   1. 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:4.3.3'  // Google Services plugin
        }
      }
      
      allprojects {
        // ...
      
        repositories {
          // Check that you have the following line (if not, add it):
          google()  // Google's Maven repository
          // ...
        }
      }
      

   2. 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

1. To your module (app-level) Gradle file (usually app/build.gradle), add the dependencies for the Firebase products that you want to use in your app.

   You can add any of the supported Firebase products to your Android app.

   For an optimal experience with Firebase Cloud Messaging, we recommend enabling Google Analytics in your project. Also, as part of setting up Analytics, you need to add the Firebase SDK for Analytics to your app.

   Analytics enabled

   dependencies {
     // ...
   
     // Add the Firebase SDK for Google Analytics
     implementation 'com.google.firebase:firebase-analytics:17.4.4'
   
     // Add the SDK for Firebase Cloud Messaging
     implementation 'com.google.firebase:firebase-messaging:20.2.3'
   
     // Getting a "Could not find" error? Make sure that you've added
     // Google's Maven repository to your root-level build.gradle file
   }
   

   Analytics not enabled

   dependencies {
     // ...
   
     // Add the SDK for Firebase Cloud Messaging
     implementation 'com.google.firebase:firebase-messaging:20.2.3'
   
     // Getting a "Could not find" error? Make sure that you've added
     // Google's Maven repository to your root-level build.gradle file
   }
   

2. Sync your app to ensure that all dependencies have the necessary versions.

3. If you added Analytics, run your app to send verification to Firebase that you've successfully integrated Firebase. Otherwise, you can skip the verification step.

   Your device logs will display the Firebase verification that initialization is complete. If you ran your app on an emulator that has network access, the Firebase console notifies you that your app connection is complete.

Access the registration token

To send a message to a specific device, you need to know that device's registration token. Because you'll need to enter the token in a field in the Notifications console to complete this tutorial, make sure to copy the token or securely store it after you retrieve it.

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():

FirebaseInstanceId.getInstance().getInstanceId()
        .addOnCompleteListener(new OnCompleteListener<InstanceIdResult>() {
            @Override
            public void onComplete(@NonNull Task<InstanceIdResult> task) {
                if (!task.isSuccessful()) {
                    Log.w(TAG, "getInstanceId failed", task.getException());
                    return;
                }

                // Get new Instance ID token
                String token = task.getResult().getToken();

                // Log and toast
                String msg = getString(R.string.msg_token_fmt, token);
                Log.d(TAG, msg);
                Toast.makeText(MainActivity.this, msg, Toast.LENGTH_SHORT).show();
            }
        });
MainActivity.java

FirebaseInstanceId.getInstance().instanceId
        .addOnCompleteListener(OnCompleteListener { task ->
            if (!task.isSuccessful) {
                Log.w(TAG, "getInstanceId failed", task.exception)
                return@OnCompleteListener
            }

            // Get new Instance ID token
            val token = task.result?.token

            // Log and toast
            val msg = getString(R.string.msg_token_fmt, token)
            Log.d(TAG, msg)
            Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT).show()
        })
MainActivity.kt

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.

Send a test notification message

1. Install and run the app on the target device.

2. Make sure the app is in the background on the device.

3. Open the Notifications composer and select New notification.

4. Enter the message text.

5. Select Send test message.

6. In the field labeled Add an FCM registration token, enter the registration token you obtained in a previous section of this guide.

7. Click Test

After you click Test, the targeted client device (with the app in the background) should receive the notification in the system notifications tray .

For insight into message delivery to your app, see the FCM reporting dashboard, which records the number of messages sent and opened on iOS and Android devices, along with data for "impressions" (notifications seen by users) for Android apps.

Next steps

Send messages to foregrounded apps

Once you have successfully sent notification messages while your app is in the background, see Receive Messages in an Android App to get started sending to foregrounded apps.

Go beyond notification messages

To go beyond notification messages and add other, more advanced behavior to your app, see:

• Receive Messages in an Android App
• Send Messages to Multiple Devices