Comments on: Beware using DateFormat for input validation

By: Hale

Hale — Tue, 20 Jul 2004 17:21:51 +0000

One more note: without the dateFormat.setLenient(false), the SimpleDateFormatter will convert a date like 12/44/2004 into something like 1/13/2005. It doesn’t catch months_out_of_range or days_in_month_out_of_range errors.

By: Colin Hawkett

Colin Hawkett — Fri, 11 Jun 2004 16:13:47 +0000

We ended up doing this to force it….

* Created on 11-Jun-04
*/
package domain;

import java.text.ParseException;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;

/**

* @author Colin Hawkett
*/
public class StrictDateFormat extends SimpleDateFormat {
public StrictDateFormat(String format) {
super(format);
}

public java.util.Date parse(String dateString) throws ParseException {
if(dateString.length() != toPattern.length()) throw new ParseException(“Input string wrong length!”, 0);
ParsePosition pos = new ParsePosition(0);
java.util.Date date = super.parse(dateString, pos);
if((date == null) || (pos.getErrorIndex() != -1)) throw new ParseException(“Dodgy date string!”, pos.getIndex());
if(pos.getIndex() != toPattern().length()) throw new ParseException(“Did not use entire string to parse date!”, pos.getIndex());
else return date;
}
}

By: Joey Gibson

Joey Gibson — Wed, 19 May 2004 16:13:13 +0000

We discovered the non-threadsafeness of SimpleDateFormat a few months ago. It bit us big time…

By: Sam Newman

Sam Newman — Wed, 19 May 2004 09:30:12 +0000

According to the documentation, DateFormat isn’t synchronized either:

“Date formats are not synchronized. It is recommended to create separate format instances for each thread. If multiple threads access a format concurrently, it must be synchronized externally.”

By: Jed Wesley-Smith

Jed Wesley-Smith — Wed, 19 May 2004 04:23:00 +0000

Actually, I think its just SimpleDateFormat that is not thread-safe, but don’t quote me. I generally use the Jakarta commons-lang 2.0 FastDateFormat class, thread-safe and quicker than SimpleDateFormat.

What context are you entering dates? There are a number of good javascript date validation scripts around, and some free Java implementations as well.

Edited to stop layout problem:

Javascript Validation Links validation&btnG=Search