title: What's the difference from Calendar.DATE and Calendar.DAY_OF_MONTH?
body: <p>Is there any difference when I called:</p>
  
  <pre><code>calendar.get(Calendar.DATE);
  calendar.get(Calendar.DAY_OF_MONTH);
  calendar.set(Calendar.DATE, day);
  calendar.set(Calendar.DAY_OF_MONTH, day);
  </code></pre>
  
  <p>?</p>