How to parse case-insensitive strings with JSR-310 DateTimeFormatter?

Question

JSR-310 has a handy class DateTimeFormatter which allows you to construct a DateTimeFormatter. I particularly like the pattern(String) method - see javadoc

However, I hit a problem whereby this is case sensitive -- e.g.

DateTimeFormatters.pattern("dd-MMM-yyyy");

matches with "01-Jan-2012", but not with "01-JAN-2012" or "01-jan-2012".

One approach would be to break the string down and parse components, or another would be to use Regex to replace the case-insensitive strings with the case-sensitive string.

But it feels like there ought to be an easier way...

score 29 · Accepted Answer · edited Apr 07 '16 at 14:36

29

And there is... according to the User Guide (offline, see JavaDoc instead), you should use DateTimeFormatterBuilder to build a complex DateTimeFormatter

e.g.

DateTimeFormatterBuilder builder = new DateTimeFormatterBuilder();
builder.parseCaseInsensitive();
builder.appendPattern("dd-MMM-yyyy");
DateTimeFormatter dateFormat = builder.toFormatter();

edited Apr 07 '16 at 14:36

borjab

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answered May 29 '12 at 10:59

amaidment

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3

Slightly neater third line: builder.appendPattern("dd-MMM-yyyy"); – JodaStephen Jun 25 '12 at 14:43
2

Slightly neater: most of the times, a builder provides methods *returning* the builder, so you can use *method chaining*: `new DateTimeFormatterBuilder().parseCaseInsensitive().appendPattern...`. – MC Emperor Oct 20 '21 at 19:13
1

Further improvement: [Never use `SimpleDateFormat` or `DateTimeFormatter` without a `Locale`](https://stackoverflow.com/a/65544056/10819573). Use `.toFormatter(Locale.ENGLISH)` in this case. – Arvind Kumar Avinash Nov 13 '22 at 15:35

score 10 · Answer 2 · answered Feb 03 '16 at 14:58

10

This alternative is usefull for initializating static variables:

DateTimeFormatter myFormatter = new DateTimeFormatterBuilder()
                               .parseCaseInsensitive()
                               .appendPattern("dd-MMM-yyyy")
                               .toFormatter(Locale.ENGLISH);

answered Feb 03 '16 at 14:58

borjab

11,149
6
71
98

4

Seems to duplicate the [accepted Answer](http://stackoverflow.com/a/10797809/642706) from a couple years earlier – Basil Bourque Apr 07 '16 at 13:28

score 4 · Answer 3 · answered Apr 25 '18 at 11:58

Just an extra Note, the order matters.

This is case insensitive:

            DateTimeFormatter format = new DateTimeFormatterBuilder()
                .parseCaseInsensitive()
                .parseLenient()
                .appendPattern("HH:mm EEEE")
                .toFormatter();

This is not:

            DateTimeFormatter format = new DateTimeFormatterBuilder()
                .appendPattern("HH:mm EEEE")
                .parseCaseInsensitive()
                .parseLenient()
                .toFormatter();

Good point! Further improvement: [Never use `SimpleDateFormat` or `DateTimeFormatter` without a `Locale`](https://stackoverflow.com/a/65544056/10819573). Use `.toFormatter(Locale.ENGLISH)` in this case. — Arvind Kumar Avinash, Nov 13 '22 at 15:34

How to parse case-insensitive strings with JSR-310 DateTimeFormatter?

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