title: Read empty cells from the table JTable into the array
body: <p>I need to read data from the table <code>JTable</code>. The problem is that this table may contain empty cells. In this case the error message is:</p>
  
  <blockquote>
    <p>Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException</p>
  </blockquote>
  
  <p>How to avoid this error message?</p>
  
  <pre><code>mdArrivals = new QueryTableModelFS();
  
  tbArrivals = new JTable(mdArrivals);
  
  String STA = mdArrivals.getValueAt(i,1).toString();
  </code></pre>