当我从 xlsx 读取到 java 时，为什么日期字段会混乱？

Question

我在 excel 中将日期列格式设置为 M/d/yyyy，但是，当我在 Java 中读取单元格值时，日期似乎是“05/Jan/2021”，我对什么感到困惑发生？谁能帮我解决我做错了什么？

XSSFWorkbook wb1 = new XSSFWorkbook(fis1);   
XSSFSheet sheet1 = wb1.getSheetAt(0);     //creating a Sheet object to retrieve object  
Iterator<Row> itr1 = sheet1.iterator();    //iterating over excel file  
ArrayList recipientids = new ArrayList();

for (Row row : sheet1) { // For each Row.
    Cell cell = row.getCell(4); // Get the Cell at the Index / Column you want.
    Cell cell2 = row.getCell(5);
    CellType type = cell2.getCellType();
    if (type == CellType.NUMERIC) {
        Date date = new Date();
        SimpleDateFormat DateFor = new SimpleDateFormat("M/d/yyyy");
              String dateString = cell2.toString();
        String newdate = dateString.replace("-", "/");

        arraylist.add(cell+"-"+newdate);
    }
}

但是，当我尝试格式化时，我无法格式化/解析异常。

Answer 1

如前所述，不要使用SimpleDateFormat 甚至Date。自 Java 8 以来，Java 中有一个新的日期和时间 API。

检查以下内容，可能会有所帮助：

XSSFWorkbook wb1 = new XSSFWorkbook(fis1);   
XSSFSheet sheet1 = wb1.getSheetAt(0);     //creating a Sheet object to retrieve object  
Iterator<Row> itr1 = sheet1.iterator();    //iterating over excel file  
ArrayList recipientids = new ArrayList();
DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("M/d/yyyy");

for (Row row : sheet1) { // For each Row.
    Cell cell = row.getCell(4); // Get the Cell at the Index / Column you want.
    Cell cell2 = row.getCell(5);
    CellType type = cell2.getCellType();
    if (type == CellType.NUMERIC) {
        String dateString = cell2.toString();
        LocalDate date = LocalDate.parse(dateString, dateTimeFormatter);
        System.out.println(date.format(dateTimeFormatter)); // Formats this date using the specified formatter.
    }
}