title: Jexcelapi Getting the number of rows in one column
body: <p>I can find the number of rows in the excel document using 
  sheet.getRows(); 
  however the rows in my excel file are of different lengths, how could I get the number of rows in only 1 column. 
  I've found 
  <a href="http://www.coderanch.com/t/63874/open-source/number-rows-column-Excel-JXL" rel="nofollow">getting rows in file</a> and
  <a href="http://jexcelapi.sourceforge.net/resources/javadocs/2_6_10/docs/jxl/Sheet.html" rel="nofollow">List of methods in the library</a>
  but neither have the answer.</p>