How can I tell if a listener is already running?
<p>I am adding a event listener to my Singleton class.  I am adding the listener in a add method.</p>

<pre><code> public void add(TCComponentItemRevision tcRevision, TCComponentDataset selectedDataset) {
  String revMasterForm;

  tcRevision.getSession().addAIFComponentEventListener(this);

  try {
     revMasterForm = tcRevision.getRelatedComponent("IMAN_master_form_rev").getUid();
     RevDataset pp = new RevDataset(tcRevision, selectedDataset, revMasterForm);
     if (!rds.contains(pp)) {
        rds.add(pp);
     }     
  }
  catch (TCException e) {

     e.printStackTrace();
  }

  fireTableDataChanged();
}
</code></pre>

<p>I only want the lister to be adding once. So I figure there has to be some sort of a check.
something like</p>

<pre><code>if (listener value == null) {
    tcRevision.getSession().addAIFComponentEventListener(this);
}
</code></pre>

<p>But I am not sure how to get the listener value?</p>
