title: from Service, call Activity method (if it's in the foreground)
body: <p>From an Android <strong>Service</strong>, I would like to call an <strong>Activity</strong> method, but only if the Activity is in the <strong>foreground</strong>.</p>
  
  <p>I would like nothing to happen in case the Activity is not in the foreground.</p>
  
  <p>Which is the simplest way to achieve that?</p>