Firebase instance id: deprecation of getId() in 21.0.0

Fcm Token

Before deprecation

val fcmToken = FirebaseInstanceId.getInstance().getToken()

Replacement

val fcmToken = FirebaseMessaging.getInstance().getToken()

---

FirebaseInstanceId#getId

Before deprecation

val istanceId = FirebaseInstanceId.getInstance().getId()

Replacement

Checking out the code of FirebaseInstanceId#getId() I saw the suggestion that you should use FirebaseInstallations#getId instead.

This method is deprecated

Use FirebaseInstallations.getId() instead.

val instanceId = FirebaseInstallation.getInstance().getId()

FirebaseInstanceId class is deprecated, to get token use FirebaseMessagingClass. The token can be generated using the following code:

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;
      }

      // Get new FCM registration token
      String token = task.getResult();

      // 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();
    }
});

Regarding the Firebase InstanceId, this is what the official document says:

public Task getInstanceId () -> This method is deprecated. For an instance identifier, use FirebaseInstallations.getId() instead. For an FCM registration token, use FirebaseMessaging.getToken() instead.