 public class MainActivity extends AppCompatActivity {      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          FirebaseInstanceId.getInstance().getInstanceId().addOnSuccessListener( MainActivity.this,  new OnSuccessListener<InstanceIdResult>() {             @Override             public void onSuccess(InstanceIdResult instanceIdResult)             {                 String updatedToken = instanceIdResult.getToken();                 Log.e("Updated Token",updatedToken);              }         });     