title: Determining if time is full or half hour
body: <p>I am setting up a date instance like this:</p>
  
  <pre><code>Calendar date = Calendar.getInstance();
  date.set(2015, 9, 25, 12, 0);
  </code></pre>
  
  <p>In this case, I know that it's <code>12:00</code>, a full hour, but I also have cases where I input the date parameters dynamically, so I want to determine if that date is a full or half hour.</p>
  
  <p>E.g., for <code>12:00</code> and <code>12:30</code> it would return <code>true</code>, while for <code>12:23</code> it would return false.</p>
  
  <p>I've tried <code>timeInMillis % 36000000</code> from another answer, but it didn't work.</p>