ATG Date Tag Converter is Buggy

Leaf on my car on Flickr

(Photo: Leaf on my car by exfordy)

The ATG Date Tag Converter is buggy because Java’s DateFormat is inherently unsafe for multithreaded use.  This is documented in ATG PR #123210 DateTagConverter.convertObjectToString() method is not thread safe.

You run into this problem whenever you do something like this.

Unfortunately there is no work around.  If using the Date Tag Converter is not causing problems for you, i.e you don’t see a stack trace like below, then you can ignore this bug.

2009-04-17 00:19:08,220 ERROR [nucleusNamespace.atg.dynamo.servlet.dafpipeline.DynamoServlet] java.lang.ArrayIndexOutOfBoundsException: 502
  at sun.util.calendar.BaseCalendar.getCalendarDateFromFixedDate(
  at java.util.GregorianCalendar.computeFields(
  at java.util.GregorianCalendar.computeFields(
  at java.util.Calendar.setTimeInMillis(
  at java.util.Calendar.setTime(
  at java.text.SimpleDateFormat.format(
  at java.text.SimpleDateFormat.format(
  at java.text.DateFormat.format(
  at atg.droplet.DateTagConverter.convertObjectToString(

But if you do see a bug like this then you might need to create a custom droplet to format the date.  The droplet should only use DateFormat instances that are not static.  I usually make my DateFormat instances local.

ATG Currency Converter Not Working With JSTL c:set

Currency conversion confusion on Flickr!

This JSP code was not outputting the properly formatted amount.

I tried forcing it by specifying the conversion parameters.

I then debugged atg.droplet.CurrencyTagConverter using Eclipse and found this code being executed.

public String convertObjectToString(DynamoHttpServletRequest pRequest,
                                 Object pValue, Properties pAttributes)
  throws TagConversionException
  if ((pValue == null) || (pValue instanceof String))
    return (String)pValue;

It turns out pValue was a String which is why it was never being formatted.  But why is it a String?

Well the code that sets dollars looks like this.


Apparently c:set converts the Double to a String.

To work around this problem I did this.


For further reading please see Tag Converters in the ATG Page Developer’s Guide.