DateTimeFormatter auto-corrects invalid (syntactically possible) calendar date

Question

Java DateTimeFormatter throws an exception for when you try a date that goes outside of a possible range, for example:

DateTimeFormatter dtf = D         


        

Answer 1

You can use a STRICT resolver style:

import static java.time.format.ResolverStyle.STRICT;

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("M/d/uuuu").withResolverStyle(STRICT);

By default, ofPattern uses a SMART resolver style which will use reasonable defaults.

Note that I have used uuuu instead of yyyy, i.e. YEAR instead of YEAR_OF_ERA. Assuming you are in a Gregorian calendar system, the two are equivalent for years in the current era (year 1 or greater). The difference is explained in more details in the links above.