If its a jsp page using the class its jsp file needs to have its timestamp updated in order to trigger recompilation of the page to see the change. The previous servlet class will be used and its use of constants is embedded in the servlet class file.
It's not a JSP. Both times involved struts action subclasses, being called by the struts action servlet.
However this sounds like it would cause exactly the problem I am seeing, if it also affects other classes rather than just JSPs. But I can't see any other classes being cached anywhere like the JSPs.
I think I had this problem a long time ago, and resorted to recompilling all classes. I'm not sure it was the same problem, but recompilling all classes instead of only those I modified did solve a problem for me.
Have a look at :
I had some similar problems like you have and after deleting those files I coudl successfuly redeploy my .war's