title: Updating UI when it's onPause or in background
body: <p>I have two activities, A and B. If A is started and then B is started, the A goes to onPause.</p>
  
  <p>In this situation, if I want to update UI of Activity A, what should I do?</p>
  
  <p>I don't have any problem with it on emulator. I mean in this situation I can update UI of Activity A without any problem, but it doesn't work on a real device(cell phone) and noting changed. </p>
  
  <p>What is the solution/solutions?</p>
  
  <p>Thank you in advance.</p>