title: Android | Start Service before MainActiviy starts
body: <p><code>onTokenRefresh()</code> in <code>FirebaseInstanceIDService</code> </p>
  
  <p>starts after MainActivity starts. I think this is the reason why <code>FirebaseInstanceId.getInstance().getToken();</code> sometimes <code>=null</code></p>
  
  <p>How can I start <code>FirebaseInstanceIDService</code> before MainActivity starts?</p>
  
  <p>Thanks for your answers, and sorry for my bad English :)</p>