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