title: java get week of year for given a date
body: <p>how can I get a week of the year given a date?
  I tried the following code:</p>
  
  <pre><code>  Calendar sDateCalendar = new GregorianCalendar();
    sDateCalendar.set(Integer.parseInt(sDateYearAAAA), Integer.parseInt(sDateMonthMM)-1, Integer.parseInt(sDateDayDD));
    System.out.format("sDateCalendar %tc\n", sDateCalendar);        
    iStartWeek = sDateCalendar.getWeekYear();
    System.out.println("iStartWeek "+iStartWeek+ " "+sDateCalendar.WEEK_OF_YEAR);
  </code></pre>
  
  <p>and i obtain:
  sDateCalendar lun apr 23 11:58:39 CEST 2012
  iStartWeek 2012 3</p>
  
  <p>while the correct week of year is 17. Can someone help me ?</p>