title: how to check alert is visible android
body: <p>how to check if my alert is already showing on screen ?</p>
  
  <pre><code> AlertDialog.Builder alert = new AlertDialog.Builder(this);
  
   alert.show();
  </code></pre>
  
  <p>I can maintain state by adding a flag in my code to set and reset, but if there is already a method that I can re use ?</p>