title: How do I display countdown timer in TextView?
body: <p>I have <code>Calendar</code> Object</p>
  
  <pre><code>Calendar cal = Calendar.getInstance();
  int hh = cal.get(Calendar.HOUR);
  int mm = cal.get(Calendar.MINUTE);
  int ss = cal.get(Calendar.SECOND);
  </code></pre>
  
  <p>And to format time</p>
  
  <pre><code>SimpleDateFormat sdf = new SimpleDateFormat("h:mm:s a", Locale.US);
  </code></pre>
  
  <p>I want my <code>TextView</code> to display count down time in <code>hh:mm:ss</code> format</p>
  
  <pre><code>Time left: 03:25:12
  Time left: 03:25:11
  Time left: 03:25:10 
  Time left: 03:25:09
  .
  .
  . so on and stop the countdown after 3 hours, 25 minutes and 8 seconds.
  </code></pre>
  
  <p>After times is lapsed the <code>TextView</code> should display <code>Time left: 00:00:00</code>.</p>