Java: DateTimeFormatter fail to parse time string when seconds and milliseconds are all 0s?(Java:当秒和毫秒都为 0 时，DateTimeFormatter 无法解析时间字符串?)

问题描述

基本上，我使用以下代码将字符串解析为 LocalDateTime，这在大多数情况下都可以正常工作.

DateTimeFormatter dtformatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmssSSS");

但是，我遇到秒和毫秒为 00000 的情况，这是解析器失败并打印 LocalDateTime 2018-03-01T09:16 而不是 2018-03-01T09:16:00.000.

System.out.println(LocalDateTime.parse("20180301091600000",dtformatter));

(请注意，在我的代码中，我必须将字符串解析为 LocalDateTime，进行一些比较，然后最后将 LocalDateTime 打印到 csv)

如何修复它以使其打印 2018-03-01T09:16:00.000 而不是 2018-03-01T09:16 ?

仅供参考，我正在使用 jdk10.

我不知道为什么它不起作用，它似乎是一个 bug 因为当我使用:

20180301091600001 结果是 2018-03-01T09:16:00.001----------------^ -----------------^^^^^^

还有另一个测试:

2018030100000000 结果是 2018-03-01T00:00--------^^^------------------^^^^^^^^^^^

解析器好像忽略了秒和毫秒为零的时候，为什么?

为什么?的完整解释在 Basil Bourque 的回答中.p>

解决方案

这是一个快速修复，您可以使用其他格式化程序，如下所示:

var 结果 = LocalDateTime.parse("20180301091600000", dtformatter).format(DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss:SSS"));

输出

2018-03-01T09:16:00:000

Basically, I am using the following code to parse string as LocalDateTime, which works fine most of the time.

DateTimeFormatter dtformatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmssSSS");

However, I encounter cases where the seconds and millseconds are 00000 and this is when the parser fails and print a LocalDateTime 2018-03-01T09:16 instead of 2018-03-01T09:16:00.000.

System.out.println(LocalDateTime.parse("20180301091600000",dtformatter));

(Note that in my code, I have to parse string as LocalDateTime, do some comparison and then at the end, print LocalDateTime to csv)

How can I fix it to make it print 2018-03-01T09:16:00.000 instead of 2018-03-01T09:16 ?

FYI, I am using jdk10.

I'm not sure why it's not work, it seems it is a bug because when I use :

20180301091600001        result is      2018-03-01T09:16:00.001
----------------^                       -----------------^^^^^^

Also another test :

2018030100000000         result is      2018-03-01T00:00
--------^^^-----                        -----------^^^^^^^^^^^

It seems that the parser ignore the seconds and millisecond when it is zero, why?

The full explanation why?, is in the answer of Basil Bourque.

Solution

Here is a quick fix where you can use another formatter like this :

var result = LocalDateTime.parse("20180301091600000", dtformatter)
                .format(DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss:SSS"));

Output

2018-03-01T09:16:00:000

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