I have a SimpleDateFormat with the pattern yyyy-Md"
, and the following scenario:
String str = "02-03-04";
SimpleDateFormat f = new SimpleDateFormat("yyyy-M-d");
f.setLenient(false);
System.out.println(f.parse(str));
The output is Sat Mar 04 00:00:00 EST 2
My goal was to only catch dates in the format like 2004-02-03 and to ignore 02-03-04. I thought the yyyy in the pattern would require a 4 digit year, but clearly this is not the case. Can anyone explain why this is not throwing a parse exception? I would like it to...
Well, I can explain it from the docs :
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 AD
It's possible that Joda Time would be stricter - and it's a better API in general, IMO...
You could always throw an exception if the year is less than 1000 after parsing...
Using java.time , that input with that formatting pattern fails, just as you expected.
LocalDate
.parse(
"02-03-04" ,
DateTimeFormatter.ofPattern ( "uuuu-M-d" )
)
…throws java.time.format.DateTimeParseException
The classes you were using are now supplanted by the modern java.time classes defined in JSR 310 and built into Java 8 and later.
The LocalDate
class represents a date-only value without time-of-day and without time zone or offset-from-UTC .
Define a custom formatting pattern as you asked. Use the DateTimeFormatter
class.
DateTimeFormatter f = DateTimeFormatter.ofPattern ( "uuuu-M-d" );
Try to parse your input.
String input = "02-03-04";
LocalDate localDate = LocalDate.parse ( input , f );
We encounter a DateTimeParseException
, failing on the missing century of the year of the input. Just as you expected.
Exception in thread "main" java.time.format.DateTimeParseException: Text '02-03-04' could not be parsed at index 0
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date
, Calendar
, & SimpleDateFormat
.
To learn more, see the Oracle Tutorial . And search Stack Overflow for many examples and explanations. Specification is JSR 310 .
The Joda-Time project, now in maintenance mode , advises migration to the java.time classes.
You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.*
classes.
Where to obtain the java.time classes?
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval
, YearWeek
, YearQuarter
, and more .
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