Java 11 can't convert String To LocalDateTime in some case

Question

I have these code below:

private void convertStringDatePosted() {
    String stringDatePosted = "20 Janeiro 2021 00:26";
    Locale locale = new Locale("pt", "MZ");
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("d MMMM yyyy HH:mm").withLocale(locale);
    LocalDateTime aa = LocalDateTime.parse(stringDatePosted, formatter);
    System.out.println(aa);
}

When I ran code with java 8, it work. But with java 11, it throw this Exception: java.time.format.DateTimeParseException: Text '20 Janeiro 2021 00:26' could not be parsed at index 3.

I also have a similar situation with the case where there is a zone in the string I want to convert, the code is:

protected LocalDateTime getDatePosted() {
    String dateScraped = "2021-08-15 09:00:28 (UTC+01:00)";
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss (z)");
    return LocalDateTime.parse(dateScraped, formatter);
}

If run with java 8, it still work but with java 11 it not. The Exception is: java.time.format.DateTimeParseException: Text '20 Janeiro 2021 00:26' could not be parsed at index 24.

This error occur on macOS, i have not try on other OS yet.

I don't know if this error is due to java version or something else. Looking forward to your reply. Thanks a lot!

Answer 1

Capital or small J in janeiro?

It seems to me that there are two bugs: One in your string, which should have a small j in janeiro, and one in Java 8, which accepts the capital J that you had. Said having learned just a few words of Portuguese when I was in Portugal some decades ago

Month names in different languages are a part of the locale data. Java can get its locale data from up to four sources. The default in Java 8 is Java’s built-in locale data from since early versions of Java. From Java 9 the default is CLDR, Unicode Common Locale Data Repository. So in Java 8 Java’s own locale data have the upper case J. CLDR, which is also available in Java 8 through a system property, has a small j. An interesting observation is that when I instruct Java 11 to use Java’s own locale data, it also shows the small j. The error from Java 8 has been fixed.

There are many possible solutions. One is to instruct your formatter not to care about case when parsing:

    String stringDatePosted = "20 Janeiro 2021 00:26";
    Locale locale = new Locale("pt", "MZ");
    DateTimeFormatter formatter = new DateTimeFormatterBuilder()
            .parseCaseInsensitive()
            .appendPattern("d MMMM yyyy HH:mm")
            .toFormatter(locale);
    LocalDateTime aa = LocalDateTime.parse(stringDatePosted, formatter);
    System.out.println(aa);

Output is:

2021-01-20T00:26

Parsing the UTC offset

I have not been able to reproduce your other example. Your getDatePosted method runs fine on my Oracle jdk-11.0.3 on Mac and returns 2021-08-15T09:00:28. I don’t know why it did not on your computer.

There’s another problem with your code, though: You are parsing into a LocalDateTime thus throwing the time zone information away. Don’t do that. For example the strings 2021-08-15 09:00:28 (UTC-12:00) and 2021-08-15 09:00:28 (UTC+14:00) denote very different points in tome, 26 hours apart, but will be parsed into the same LocalDateTime. Parse into a ZonedDateTime to retain the time zone. If you need the time in a different time zone (such as your own), convert to a ZonedDateTime in that time zone. Do not use LocalDateTime if by any means you can avoid it.

Workaround: If you cannot get parsing of UTC+01:00 as a time zone to work, the following hack does it:

protected OffsetDateTime getDatePosted() {
    String dateScraped = "2021-08-15 09:00:28 (UTC+01:00)";
    DateTimeFormatter formatter = DateTimeFormatter
            .ofPattern("yyyy-MM-dd HH:mm:ss ('UTC'xxx)", Locale.ROOT);
    return OffsetDateTime.parse(dateScraped, formatter);
}

Now the method returns 2021-08-15T09:00:28+01:00. You also notice that the UTC offset has been retained.

Link

Related question with more information on locale data in different Java versions: JDK dateformatter parsing DayOfWeek in German locale, java8 vs java9