Simpledateformat...not so simple

Question

The Simple Date Format has some weird behavior. I'm trying to test whether a date is in the future, and I initially used a 2 digit year.
SimpleDateFormat sdf = new SimpleDateFormat("ddMMyy");
sdf.setLenient(false);
String inputDate = sdf.format(date);
Date formattedInputDate = sdf.parse(inputDate); The reason for formatting the input date and then parsing it is to basically ignore the hour,minute,second. There are probably other ways to do it.
Anyway, what's really bizarre, is that apparently there is some weird algorithm in the parse method for determining what the 1st 2 digits are.
For example, if the year is 89 it gets translated to 1989. 05 gets translated to 2005. OK, that seems to make sense. But how about this
1)Anything from 00 to <current date>2026 gets translated to the years 2000-2026.
2)Anything after the current date, 20 years from today gets translated to 19xx! So 061026 gets translated to Oct 6, 2026 (a future date), whereas 071026 gets translated to Oct 7, 1926 (a past date)
Ok, I got around this with a 4 digit year, but BIZARRE behavior, huh?

Answer 1

The Simple Date Format has some weird behavior. I'm
trying to test whether a date is in the future, and I
initially used a 2 digit year.
SimpleDateFormat sdf = new
SimpleDateFormat("ddMMyy");
sdf.setLenient(false);
String inputDate = sdf.format(date);
Date formattedInputDate = sdf.parse(inputDate); The reason for formatting the input date and then
parsing it is to basically ignore the
hour,minute,second. There are probably other ways to
do it.
Anyway, what's really bizarre, is that apparently
there is some weird algorithm in the parse method for
determining what the 1st 2 digits are.
For example, if the year is 89 it gets translated
to 1989. 05 gets translated to 2005. OK, that seems
to make sense. But how about this
)Anything from 00 to <current date>2026 gets
translated to the years 2000-2026.
2)Anything after the current date, 20 years from
today gets translated to 19xx! So 061026 gets
translated to Oct 6, 2026 (a future date), whereas
071026 gets translated to Oct 7, 1926 (a past date)
Ok, I got around this with a 4 digit year, but
BIZARRE behavior, huh?Actually, this behavior is documented in the Java api for SimpleDateFormat:
http://java.sun.com/j2se/1.5.0/docs/api/java/text/SimpleDateFormat.html
Pattern letters are usually repeated, as their number determines the exact presentation:
* Year: For formatting, if the number of pattern letters is 2, the year is truncated to 2 digits; otherwise it is interpreted as a number.
For parsing, if the number of pattern letters is more than 2, the year is interpreted literally, regardless of the number of digits. So using the pattern "MM/dd/yyyy", "01/11/12" parses to Jan 11, 12 A.D.
For parsing with the abbreviated year pattern ("y" or "yy"), SimpleDateFormat must interpret the abbreviated year relative to some century. It does this by adjusting dates to be within 80 years before and 20 years after the time the SimpleDateFormat instance is created. For example, using a pattern of "MM/dd/yy" and a SimpleDateFormat instance created on Jan 1, 1997, the string "01/11/12" would be interpreted as Jan 11, 2012 while the string "05/04/64" would be interpreted as May 4, 1964. During parsing, only strings consisting of exactly two digits, as defined by Character.isDigit(char), will be parsed into the default century. Any other numeric string, such as a one digit string, a three or more digit string, or a two digit string that isn't all digits (for example, "-1"), is interpreted literally. So "01/02/3" or "01/02/003" are parsed, using the same pattern, as Jan 2, 3 AD. Likewise, "01/02/-3" is parsed as Jan 2, 4 BC.
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