Java DateTimeFormatter.ISO_OFFSET_DATE_TIME Returns different values in Java 9+ compared to Java 8

Question

When running the below code I get different behaviour with different versions of the JDK:

In Java 8 I get:

2020-01-07T09:34:38.994Z

In Java 11 I get:

2020-01-07T09:37:05.55126Z

import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;

public class MyClass {
    public static void main(String args[]) {
        ZonedDateTime now = ZonedDateTime.now();

        DateTimeFormatter isoOffsetDateTime = DateTimeFormatter.ISO_OFFSET_DATE_TIME;

        String format = isoOffsetDateTime.format(now);

        System.out.println(format);
    }
}

Running in https://www.jdoodle.com/online-java-compiler/ just to make it easier to swap JDKs quickly

Is this change documented anywhere as I couldn't find anything and/or does anyone know why it's happening ? I spotted this as the DateTimeFormatter.ISO_OFFSET_DATE_TIME is the default Jackson formatter for a ZonedDateTime.

Answer 1

The behaviour of the formatter hasn't changed, but the thing you're formatting has.

The precision of datetimes returned by now() methods increased. JDK-8068730