attribute listeners!

[ashok khetan]

A class that will recieve notification if an Attribute is added to or removed from a session will implement which interface?(From javaranch mock exam)
1) HttpSessionListener
2) HttpSessionObjectListener
3) HttpSessionAttributeListener
4) HttpSessionBindingListener

--> I think answer should be both 3) and 4), becos' HttpSessionAttributeListener has attributeAdded() and attributeRemoved() methods while HttpSessionBindingListener has valueBound() and valueUnbound() methods.Correct me if i am wrong.
ashok.

[Tony Alicea]

I agree.
They seem to do similar functions (?) except that HttpSessionAttributeListener has an "extra" attributeReplaced() method.

[satish kolli]

Both are different..
One will notify the object(itself) when it is bound or unbound from session.
The other one will notify you when an attribute gets added/removed/replaced.
Check this link: http://www.javaranch.com/ubb/Forum18/HTML/000181.html
Thanks!
Satish Kolli, SCJP2

[Gagan Indus]

I Agree with Satish , they are indeed different.
So i guess ans should only be option 3)
( But if the question explicitly order " Choose 2" , then of course add option 4) as well )

------------------
Gagan (/^_^\) SCJP2
Die-hard JavaMonk -- little Java a day , keeps u going .

[Tony Alicea]

Ah! Thanks!
"The devil is in the details..." AKA: I should read more carefully. Fatal flaw if not done at the exam!

[Win Yu]

Can anyone give me some examples about: contextListener,contextAttributeListener,sessionListener,sessionAttributeListener.I could not find example on the books.
Thanks

[Tim Duncan]

Try this article
http://www.onjava.com/pub/a/onjava/2001/04/12/listeners.html