标题不起作用生成的 excel 文件...？

我正在尝试设置标题，但它在生成的 excel 文件中不起作用，并且数据正在生成的 excel 上打印，但标题不起作用，请建议我有此代码。

public class Csv {

    public static void main(String args[]) throws IOException {
        XSSFWorkbook workbook = new XSSFWorkbook();
        XSSFSheet sheet = workbook.createSheet("My Sheet");
        //HSSFSheet sheet = wb.createSheet("Excel Sheet");
        XSSFRow rowhead;
        rowhead = sheet.createRow(0);
        rowhead.createCell(0).setCellValue("Designation");
        rowhead.createCell(1).setCellValue("Title");
        rowhead.createCell(2).setCellValue("Domain");
        rowhead.createCell(3).setCellValue("Name");


        try {

            // To connect to mongodb server
            MongoClient mongoClient = new MongoClient("localhost", 27017);

            // Now connect to your databases
            DB db = mongoClient.getDB("mytest");
            System.out.println("Connect to database successfully");

            DBCollection coll = db.getCollection("myCollection");
            System.out.println("Collection mycol selected successfully");

            DBCursor cursor = coll.find();
            int i = 0;
            while (cursor.hasNext()) {
                DBObject o = cursor.next();
                //String fname = (String) o.get("Employee ID") ; 
                String lname = (String) o.get("Designation");
                String sid = (String) o.get("Title");
                String prg = (String) o.get("Domain");
                String lvl = (String) o.get("Name");


                Row row = sheet.createRow(i);
                row.createCell(0).setCellValue(lname);
                row.createCell(1).setCellValue(sid);
                row.createCell(2).setCellValue(prg);
                row.createCell(3).setCellValue(lvl);
                i++;

            }
        } catch (Exception e) {
            System.err.println(e.getClass().getName() + ": " + e.getMessage());
        }
    }
}