I try to check a String input that is a valid date follow format dd/MM/yyyy like this:

String input = Scanner.nextLine();
DateTimeFormatter formater = DateTimeFormatter.ofPattern("dd/MM/yyyy");
try{
    LocaleDate.parse(input, formater);
}
catch(Exception e)

But it cant check some rules below:

Leap year, February 29 days.

Common year, February 28 days.

Month 1, 3, 5, 7, 8, 10, 12, max 31 days.

Month 4, 6, 9, 11, max 30 days.

When i use input = "30/02/2022", it's legal. I use netbeans 8.2 and jdk 1.8. Are they support some methods for checking these rules ? Thanks very much.

CodePudding user response：

There are two things you need to change in your formatter:

• Use uuuu instead of yyyy. It's easy to try the latter, but y means "year within ERA". It doesn't know whether it's BC or AD. u means "year" including ERA information.
• Apparently, by default the resolver style is not strict. Use .withResolverStyle(ResolverStyle.STRICT) to return a strict copy of the formatter.

CodePudding user response：

You need to enable the strict mode of the DateTimeFormatter :

DateTimeFormatter formater = DateTimeFormatter.ofPattern("dd/MM/yyyy")
                            .withResolverStyle(ResolverStyle.STRICT);

LocaleDate.parse("30/02/2022, formater); will then throw an exception.