title: How to only get number of sheets which is not hidden in Apache POI
body: <p>All:</p>
  
  <p>I am pretty new to Apache POI, when I parse an Excel file, I need to know the number of sheets need to be shown, but .getNumberOfSheets() only give me all sheets, I wonder how can I know which sheets have been hidden(when u right click on a sheet tab and choose "Hide") so that I can skip counting that?</p>
  
  <p>Thanks</p>