title: Day of month - java calendar
body: <p>I want get, how much month have got days. I have got this code:</p>
  
  <pre><code>    Calendar cal = Calendar.getInstance();
      cal.set(2013, 1, 1);
      System.out.println(cal.getActualMaximum(cal.DAY_OF_MONTH));
  </code></pre>
  
  <p>Januar of year 2013 (and other else yaers :)) have got 31 days, but, I'm still getting 28, do you know, where I have got mistake? 
  Thank you.</p>