Scala/Java 解析日期未知格式

Question

I have the following code:

val dateString = "12/Sep/2017:11:25:29 +0200"
println(LocalDateTime.parse(
    dateString, 
    DateTimeFormatter.ofPattern("dd/LLL/yyyy:HH:mm:ss X")
));

and the following error:

Exception in thread "main" java.time.format.DateTimeParseException:
Text '12/Sep/2017:11:25:29 +0200' could not be parsed at index 3

What is wrong in my format? I read https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html but do not find the correct one

EDIT1: "dd/MMM/yyyy:HH:mm:ss X" does not work either

Answer 1

You have to use M instead of L ( L is for the numeric format):

"dd/MMM/yyyy:HH:mm:ss X"

You probably have also to set the Locale that java will use to interpret the month (probably your locale is not english)

LocalDateTime.parse("12/Sep/2017:11:25:29 +0200", DateTimeFormatter.ofPattern("dd/MMM/yyyy:HH:mm:ss X", Locale.ENGLISH));

This works for me (with the locale declared, probably also L will work fine)

Answer 2

The Answer by Sinigaglia is correct but insufficient. You should specify a Locale for which Sep is recognizable as a month name. An English-speaking locale is needed such as Locale.US .

If unspecified the JVM's current default time zone is automatically implicitly applied. Sep is not a month name in Russian, French, Japanese, etc.

Tip: As a general rule, always specify explicitly your intended locale and time zone; use the optional arguments. Relying implicitly on the JVM's current defaults can be problematic.

    Locale locale = Locale.US ;
    DateTimeFormatter f = DateTimeFormatter.ofPattern( "dd/MMM/yyyy:HH:mm:ss X" ).withLocale( locale ) ;
    String input = "12/Sep/2017:11:25:29 +0200" ;
    OffsetDateTime odt = OffsetDateTime.parse( input , f ) ;

    System.out.println( odt ) ;

See this code run live on IdeOne.com .

2017-09-12T11:25:29+02:00

As for your use of L , the Javadoc explains that L is for the “standalone” month name. Some languages vary the spelling depending on whether the month is used by itself or in combination. English is not one of those languages.

Answer 3

Removing / from the input String should work. (Didn't check)

val dateString = "12 Sep 2017:11:25:29 +0200"