Issue with DateTimeParseException when using STRICT resolver style

Question

I am trying to parse a date string using the following pattern: yyMMdd and the STRICT resolver as follows:

DateTimeFormatter format         


        

Answer 1

While JodaStephen has nicely explained the reason for the exception and given one good solution (use uu rather than yy), I am offering a couple of other possible solutions:

1. The obvious one that you probably don’t want: leave the resolver style at SMART (the default). In other words either leave out .withResolverStyle(ResolverStyle.STRICT) completely or change it to .withResolverStyle(ResolverStyle.SMART).
2. Provide a default era.

For the second option here is a code example:

    DateTimeFormatter formatter = new DateTimeFormatterBuilder()
            .appendPattern("yyMMdd")
            .parseDefaulting(ChronoField.ERA, 1)
            .toFormatter()
            .withResolverStyle(ResolverStyle.STRICT);

    String expiryDate = "160501";
    LocalDate result = LocalDate.parse(expiryDate, formatter);
    
    System.out.println(result);

Output is:

2016-05-01

Where the last solution may make a difference compared to using uu in the format pattern:

1. It allows us to use a format pattern that is given to us where we cannot control whether pattern letter u or y is used.
2. With pattern letter y it will fail with an exception if the string contains a negative year. Depending on your situation and requirements this may be desirable or unacceptable.

Answer 2

The strict resolver requires an era to go with YearOfEra. Change your pattern to use "u" instead of "y" and it will work, ie. "uuMMdd".