Apache POI: Excel更改我的格式字符串

import org.apache.poi.ss.usermodel.*;

public class ExcelFormatChange {
    public static void main(String[] args) throws Exception {
        // 加载Excel文件
        Workbook workbook = WorkbookFactory.create(new File("example.xlsx"));
        Sheet sheet = workbook.getSheetAt(0);
        
        // 获取要更改格式的单元格
        Row row = sheet.getRow(0);
        Cell cell = row.getCell(0);
        
        // 获取单元格的类型
        CellType cellType = cell.getCellType();
        
        // 根据单元格的类型设置新的格式字符串
        if (cellType == CellType.NUMERIC) {
            DataFormat dataFormat = workbook.createDataFormat();
            short format = dataFormat.getFormat("#,##0.00");
            CellStyle cellStyle = workbook.createCellStyle();
            cellStyle.setDataFormat(format);
            cell.setCellStyle(cellStyle);
        } else if (cellType == CellType.STRING) {
            CellStyle cellStyle = workbook.createCellStyle();
            cellStyle.setDataFormat((short) 14); // 设置日期格式
            cell.setCellStyle(cellStyle);
        }
        
        // 保存更改后的Excel文件
        FileOutputStream outputStream = new FileOutputStream("example_modified.xlsx");
        workbook.write(outputStream);
        workbook.close();
        outputStream.close();
    }
}