Java YearMonth will not parse, but only on my computer?

Question

I have been working on a project that requires me to parse a string in this manner i have seperated out the small part that has been throwing errors,


import java.time.YearMonth;
import java.time.format.DateTimeFormatter;

public class TestingYearMonth {

    public static void main(String[] args) {
        
           YearMonth yearMonth = YearMonth.parse("Feb-17", DateTimeFormatter.ofPattern("MMM-yy"));
            System.out.println(yearMonth.getMonth() + " " + yearMonth.getYear());
        
    }
}

my teacher runs the exact same code and it returns an output no problem. but when i run it i get the following error

Exception in thread "main" java.time.format.DateTimeParseException: Text 'Feb-17' could not be parsed at index 0
    at java.base/java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:2046)
    at java.base/java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1948)
    at java.base/java.time.YearMonth.parse(YearMonth.java:295)
    at com.ethanbradley.assignment6.TestingYearMonth.main(TestingYearMonth.java:10)

we checked and my jdk is fine (jdk 11, the amazon coretto version) i really cannot see why this does not work, please help oh wise internet people....

Wow, adding Locale.US works but no other Locale seems to, do you know why? — EthanLTB, Oct 19 '21 at 01:53
@EthanLTB Different locales have different requirements on how the month value is generated/parsed, some might be `FEB` for example (excluding non English languages) — MadProgrammer, Oct 19 '21 at 02:01

Basil Bourque · Accepted Answer · 2021-10-19T05:16:13.297

5

Specify a `Locale`

Likely that the default locale of your JVM is not one that recognizes “Feb” as month of February.

Specify a Locale to determine the human language and cultural norms to be used in parsing the name of month.

Locale locale = Locale.US ; 
DateTimeFormatter f = DateTimeFormatter.ofPattern( "MMM-yy" , locale ) ;
YearMonth yearMonth = YearMonth.parse( "Feb-17" , f );

See this code run live at IdeOne.com.

ISO 8601

Using localized text for data-exchange is unwise. I suggest you educate the publisher of your data about the ISO 8601 standard formats for exchanging date-time values as text.

The standard format for year-month is YYYY-MM. Example: 2017-02.

The java.time classes use ISO 8601 formats by default.

YearMonth.parse( "2017-02" )

edited Oct 19 '21 at 05:16

answered Oct 19 '21 at 02:55

Basil Bourque

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(1) The note about ISO 8601 is nice and important. (2) I would prefer `u` to `y`. (3) To the OP: You can learn more about the importance of `Locale` with `DateTimeFormatter` from [this answer](https://stackoverflow.com/a/65544056/10819573). – Arvind Kumar Avinash Oct 19 '21 at 08:34
That's great Thanks! – EthanLTB Oct 19 '21 at 13:12
You have succeeded. :-) – Ole V.V. Oct 27 '21 at 22:20

Java YearMonth will not parse, but only on my computer?

1 Answers1

Specify a Locale

ISO 8601

Specify a `Locale`