for(Row row : sheet){
    this.dataRow = null;

    for(Cell cell : row){
        if (cell != null){
            CellReference cellRef = new CellReference(rownum, cellnum);
            switch(cell.getCellType()){
                case Cell.CELL_TYPE_STRING:
                    this.dataRow.add(cell.getRichStringCellValue().getString());
                    break;
                case Cell.CELL_TYPE_NUMERIC:
                    this.dataRow.add(cell.getNumericCellValue());
                    break;
                default:
                    this.dataRow.add("");
            }
        }
        cellnum++;
    }
}