I am reading an Excel file where I need to know if a certain cell contains the 
percentage format. I am using poi-2.5-final-20040302.jar. If you need to 
contact me my phone is 561-241-4180. I wish I could include the file, but I do 
not see a way. Here are the displays when the error occurs:

Cell Type 0
style is 165 cell value 0.016
Exception caught  Array index out of range: 165

Here is the source code I am using:
private void displayCellFormat(HSSFCell cell, int type) {
	System.out.println("Cell Type " + type);
	try {
	      HSSFCellStyle cs = cell.getCellStyle();
	      short format = cs.getDataFormat();
	      if (type == 0) {
		System.out.println("style is " + format + " cell value " + 	
			  		    cell.getNumericCellValue()); 
	      }
	      else {
	        System.out.println("style is " + format + " cell value " + 	
			                    cell.getStringCellValue()); 
	      }	
	      String formatStr = HSSFDataFormat.getBuiltinFormat(format);
	      System.out.println("format " + formatStr); 
	}catch (Exception e) {
		System.out.println("Exception caught  " + e.getMessage()); 
	}				
}

Thanks again. I love the name you gave the package HSSF.

Dora