title: Add listener in AsyncTask when called postExecute
body: <p>I have a AsyncTask class.</p>
  
  <p>here is code.</p>
  
  <pre><code>private class WaitSec extends AsyncTask&lt;Void, Void, Boolean&gt;{
      @Override
      protected Boolean doInBackground(Void... params) {
          try {
              Thread.sleep(2000);
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
  
          if(CheckSomeUtil.isItOk()) {
              return true;
          } else {
              return false;
          }
      }
      @Override
      protected void onPostExecute(Boolean aBoolean) {
          if(aBoolean)
              // in this line. is i want to set listener.
          super.onPostExecute(aBoolean);
      }
  }
  </code></pre>
  
  <p>When called onPostExecute method, i'd like to get boolean value in activity.</p>
  
  <p>Thanks.</p>