title: How to free up the memory from a Apache POI workbook once the task is over?
body: <p><br>
  I have opened a large excel file as a Apache POI workbook (using VM args to set max memory size)<br><br>
  After successfully opening the file, I read the required data and finished my work. <br><br>
  Now I want to continue further in the programming with other tasks but before I do that I want to make sure I free up the memory used up the workbook.</p>
  
  <p>I checked the API doc but there is nothing like workbook.close().</p>
  
  <p>Can someone suggest what's the right way to free up the memory taken up by the workbook?</p>