instance variables in struts action classes

[javadude]

Just a sanity check question here: My understanding is that Struts does
not, by default, create a new Action class instance per request? That
said, if one kept an instance variable in an action class, you'd better
make sure that it does not reflect any client state, correct?

Thanks in advance

 

[Oscar kind]

Just a sanity check question here: My understanding is that Struts does
not, by default, create a new Action class instance per request? That
said, if one kept an instance variable in an action class, you'd better
make sure that it does not reflect any client state, correct?

Yes. Even better, is not to use any instance variables at all: the code
in a class instance may be executed in multiple threads concurrently. The
use of any non-static, non-final instance variable introduces more bugs
(IMNSHO) than it's use can ever justify.

Form classes are a different story though: they are guaranteed to be
recreated for each request or session, depending on your configuration.
Any state information should thus be kept there.