Apache POI jar需要很长时间才能生成excel表

Question

public class WriteToExcel {
 / Initialize logger object 
 Logger log = Logger.getLogger(WriteToExcel.class.getName());

 public void write(Map> preparedData, String fileName) {

    // Define a workbook and a sheet for the report`enter code here`
    HSSFWorkbook workbook = new HSSFWorkbook();
    HSSFSheet sheet = workbook.createSheet("REPORT");

    Properties properties = new Properties();
    InputStream inputStream = null;

    try {
        Set keySet = preparedData.keySet();
        List list = new ArrayList(keySet);

        // Read config.properties 
        inputStream = new FileInputStream("./config.properties");
        properties.load(inputStream);

        System.out.println("inside excel Collections in" );
        // Sort the list so that heading row will come as first row
        Collections.sort(list);
        System.out.println("inside excel Collections out" );

        int rowNum = 0; 
      int count1 =0, count2 =0;
        // Add data to the workbook
        for (String key : list) {
            System.out.println("inside excel string key"+ ++count1 );
            Row row = sheet.createRow(rowNum++);
            List objectArray = preparedData.get(key);
            int cellNum = 0;
            for (Object obj : objectArray) {
                System.out.println("inside excel object for loop "+ ++count2 );
                Cell cell = row.createCell(cellNum++);

                if (obj instanceof Date)
                    cell.setCellValue((Date) obj);
                else if (obj instanceof Integer)
                    cell.setCellValue((Integer) obj);
                else if (obj instanceof String)
                    cell.setCellValue((String) obj);
                else if (obj instanceof Double)
                    cell.setCellValue((Double) obj);


            }
        }
        FileOutputStream fileOutputSTream;
        Calendar todaysDate = Calendar.getInstance();

        String todaysFormattedDate = Util.formatDateUnderscore(todaysDate);

        try {

            String filePath = properties.getProperty("filePath");

            String completeFilename = filePath + fileName + "_"
                    + todaysFormattedDate + ".xls";
            fileOutputSTream = new FileOutputStream(new File(
                    completeFilename));
            workbook.write(fileOutputSTream);
            fileOutputSTream.close();
        } catch (FileNotFoundException e) {
            log.error("FileNotFoundException : ", e);
        }

    } catch (Exception e) {
        log.error("Exception : ", e);
    }

 }
}

寻求帮助确定代码循环的错误;为什么这么长时间/造成这个问题？