package  excel;

 import  java.io.FileInputStream;
 import  java.io.FileNotFoundException;
 import  java.io.FileOutputStream;
 import  java.io.IOException;
 import  java.lang.NullPointerException;
 import  org.apache.poi.hssf.usermodel.HSSFCell;
 import  org.apache.poi.hssf.usermodel.HSSFRichTextString;
 import  org.apache.poi.hssf.usermodel.HSSFRow;
 import  org.apache.poi.hssf.usermodel.HSSFSheet;
 import  org.apache.poi.hssf.usermodel.HSSFWorkbook;
 import  org.apache.poi.poifs.filesystem.POIFSFileSystem;

 public   class  Main
{
    
     public   static   void  main(String[] args)  throws  FileNotFoundException, IOException
    {
        POIFSFileSystem fs =  new  POIFSFileSystem( new  FileInputStream("workbook.xls"));
        HSSFWorkbook wb =  new  HSSFWorkbook(fs);
        HSSFSheet sheet = wb.getSheetAt( 0 );
        HSSFRow row = sheet.getRow( 2 );
        HSSFCell cell = row.getCell(( short ) 3 );

         if  (cell ==  null )
        {
            cell = row.createCell(( short ) 3 );
        }

        cell.setCellType(HSSFCell.CELL_TYPE_STRING);
        cell.setCellValue( new  HSSFRichTextString("a test"));

        // Write the output to a file
        FileOutputStream fileOut =  new  FileOutputStream("workbook.xls");
        wb.write(fileOut);
        fileOut.close();
    }
}