在Java中，是否可以将日期和时间转换为没有时区的ISO 8601格式的字符串？

Question

A history table of an old source system has 2 fields regarding date/time: a date (ex: 12/20/2017) String and a time (14:33:00) String. I have no timezone information I can use. The web service I'm creating is being consumed by a UI team which wants this information as an ISO 8601 formatted String. I'm using Java 8. Is creating an ISO 8601 formatted String version to return to the UI possible without a timezone?

Answer 1

Yes, you can use DateTimeFormatter ISO_LOCAL_DATE_TIME to format without the time zone:

String input = "12/20/2017 14:33:00";
DateTimeFormatter inputFormat = DateTimeFormatter.ofPattern("MM/dd/yyyy HH:mm:ss");
LocalDateTime date = LocalDateTime.parse(input, inputFormat);
String output = DateTimeFormatter.ISO_LOCAL_DATE_TIME.format(date);
System.out.println(output);

Output:

2017-12-20T14:33:00

Answer 2

shmosel's answer is correct. I would find it clearer and cleaner to make explicit in the code that the date and the time come from separate fields:

    String dateString = "12/20/2017";
    String timeString = "14:33:00";

    DateTimeFormatter dateInputFormat = DateTimeFormatter.ofPattern("MM/dd/uuuu");
    String iso8601DateTimeString = LocalDate.parse(dateString, dateInputFormat)
            .atTime(LocalTime.parse(timeString))
            .toString();

This produces 2017-12-20T14:33 , which is ISO 8601 compliant.

Instead of toString() you may use format(DateTimeFormatter.ISO_LOCAL_DATE_TIME) . Funnily it doesn't always produce the same result: we now get 2017-12-20T14:33:00 , that is, the seconds are given even when they are 0. Both versions are ISO 8601 compliant.