title: Why dec 31 2010 returns 1 as week of year?
body: <p>For instance:</p>
  
  <pre><code>Calendar c = Calendar.getInstance();
  DateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
  c.setTime( sdf.parse("31/12/2010"));
  out.println( c.get( Calendar.WEEK_OF_YEAR ) );  
  </code></pre>
  
  <p>Prints 1</p>
  
  <p>Same happens with Joda time. </p>
  
  <p>:) </p>