Question

I have a string, is there a simple way to validate whether the string represents ISO 8601 week number in java?

String s="2012-W43-5"

This one represents 5 th day in 43 rd week in 2012.

Answer 1

Just check if SimpleDateFormat#parse() doesn’t throw a ParseException.

String string = "2012-W43-5";
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-'W'w-u");
sdf.setLenient(false);
Date date = sdf.parse(string);

Note that the setLenient(false) makes it non-lenient which thus means that overflowed values won’t roll over.