title: Want to test that a parameter value is null in querystring
body: <p>I am using a servlet to do a range of things.</p>
  
  <p>If a particular parameter "t" does not exist I want to do certain types of processing, if it does I want to do different things.</p>
  
  <p>I am trying to test the parameter t (which I save as a String called editType), using the following condition:</p>
  
  <pre><code>String editType = request.getParameter("t");
  if(!editType.isEmpty()||!(editType==null)){
      //processing here
  }
  </code></pre>
  
  <p>How do I do this test properly, because I am getting the problem of a nullpointerexception, because my code always seems to expect a value for "t" I need to be able to create a condition which doesn't expect t (allows it to be null), and do processing in that.</p>