title: apache poi - reading comments from blank and missing (null) cells
body: <p>I'm trying to read comments from all Excel documents cell's (using Apache POI).
  I have problem when empty (or missing) cells contains comments.</p>
  
  <p>Currently only solutions that I found is to:</p>
  
  <ul>
  <li>iterate every row to last not empty column</li>
  <li>get all (even empty) cells</li>
  <li>check if cell's comment is not empty</li>
  <li>if true: handle comment</li>
  </ul>
  
  <p>Some code:</p>
  
  <pre><code>if (row != null) {
    cell = row.getCell(cellNum, Row.CREATE_NULL_AS_BLANK);
    cellComment = cell.getCellComment();
    if (cellComment != null)
      ...
  }
  </code></pre>
  
  <p>Main problems is that I can't read comments from empty lines and comments which are after last not empty cell.
  Increasing performance (comparing to reading all row cells) would be nice, but main point is to read ALL documents comments. </p>