Java 8 LocalDateTime 在解析具有 00 秒的日期字符串值（如“2018-07-06 00:00:00”）时丢弃 00 秒值

Question

The code (Java 8) snippet below drops the seconds part of my date time when the seconds value is zero within the date parsed using LocalDateTime.parse , like 2018-07-10 00:00: 00 :

final DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
final LocalDateTime localDateTime = LocalDateTime.parse("2018-07-06 00:00:00", dateTimeFormatter);
final String lexicalDate = localDateTime.toString();
System.out.println("Lexical Date : "+ lexicalDate);
final XMLGregorianCalendar gregorianCalendar = DatatypeFactory.newInstance().newXMLGregorianCalendar(lexicalDate);
System.out.println("Gregorian Calendar : "+ gregorianCalendar);

The Lexical Date is printed as :

Lexical Date : 2018-07-10T00:00

instead of :

Lexical Date : 2018-07-10T00:00:00

Now this is affecting the date value of the gregorian calendar which returns null when the second is dropped. Other cases when the seconds value is greater than Zero, it works perfectly.

javax.xml.datatype.DatatypeFactory.newInstance().newXMLGregorianCalendar(lexicalDate)

The above code is returning null whenever the seconds value is dropped because of 00 seconds value within the parsed string.

Can someone assist with a better way that handles this issue using LocalDate time, otherwise it might be a bug/funny control in Java 8 LocalDateTime.

Please note I do not have control over this date value, it's coming from a third party platform.

Answer 1

Feature, not a bug

You are seeing the documented behavior of the particular DateTimeFormatter used by the LocalDateTime::toString method.

Excerpt, my emphasis:

The output will be one of the following ISO-8601 formats:

uuuu-MM-dd'T'HH:mm

uuuu-MM-dd'T'HH:mm:ss

uuuu-MM-dd'T'HH:mm:ss.SSS

uuuu-MM-dd'T'HH:mm:ss.SSSSSS

uuuu-MM-dd'T'HH:mm:ss.SSSSSSSSS

The format used will be the shortest that outputs the full value of the time where the omitted parts are implied to be zero .

If you want other behavior when generating a String to represent the value of you LocalDateTime , use a different DateTimeFormatter and pass it to LocalDateTime::format .

String output = myLocalDateTime.format( someOtherFormatter ) ;

The LocalDateTime has no “format” as it is not text. It is the job of the DateTimeFormatter to parse or generate String objects of a particular format.

Answer 2

您需要使用正确的格式化程序格式化您的日期，而不是通过调用toString()使用默认的格式化程序。

final String lexicalDate = localDateTime.format(dateTimeFormatter);

Answer 3

您可以使用以下模式来实现所需的格式：

DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ssz");

Answer 4

DateTimeFormatter removes 00 from date after parsing, you just have to reformat it again

please refer below code snippet:

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
String currentTime= "2017-10-19 22:00:00";
LocalDateTime datetime = LocalDateTime.parse(currentTime,formatter);
//2017-10-19T22:00
String formattedDate=datetime.format(formatter);
//2017-10-19 22:00:00