HFJS - final mock - q55

[Steven Colley]

Please, could anyone explain this question to me?

what the answer is "BBUBUB" ?

Tks.

[senthil rajan]

Hi Frnds,
Its a unsolvable problem for me too...

Can anybody give some idea about this???

Thanks,
Senthil.

[Raghavan Muthu]

hey dudes
can you tell what exactly that constant means.. is it an answer to a question? or any other technical term?

Good times ahead.
Raghavan alias Saravanan M

[Jigar Gosar]

if BBUBUB is correct than, it can be infered that, when setAttribute is called for the second time than valueBound(for second attribute) is called before valueUnbound (for first attribute) is called.

I have read the spec but it doesnot specify the order in which valueBound valueUnbound methods are called.

so, can some one tell me the order in which methods valueBound/valueUnbound of Interface HttpSessionBindingListener will be called for the following code.
assume there is a class called X that implements HttpSessionBindingListener. Now,

    
session.setAttribute("key", new X());
session.setAttribute("key", new X());

according to me the order must be
1. valueBound - for first object X()
2. valueUnbound - for first object X()
3. valueBound - for second object X()

but according to the answers of q55 final mock exam HFSJ, the order is

1. valueBound - for first object X()
2. valueBound - for second object X()
3. valueUnbound - for first object X()

can someone tell me the correct order in which these functions are called.

thanks.
[ April 22, 2006: Message edited by: Jigar Gosar ]

[Akshay Kiran]

SRV.7.4 Binding Attributes into a Session
A servlet can bind an object attribute into an HttpSession implementation by name.
Any object bound into a session is available to any other servlet that belongs to the
same ServletContext and handles a request identified as being a part of the same
session.
Some objects may require notification when they are placed into, or removed
from, a session. This information can be obtained by having the object implement
the HttpSessionBindingListener interface. This interface defines the following
methods that will signal an object being bound into, or being unbound from, a
session.
� valueBound
� valueUnbound
The valueBound method must be called before the object is made available via
the getAttribute method of the HttpSession interface. The valueUnbound
method must be called after the object is no longer available via the getAttribute
method of the HttpSession interface.

clearly, the order of execution is
valueBound for the first one
valueBound for the second one (because the value of the first one will be unBound only after it is replaced)
valueUnbound for the first one
(here, the string value is added, but the String class doesn't implement the HttpSessionBindingListener, so valueBound or Unbound won't be called for adding or removing "x")
valueUnbound for the second one (because it has now been replaced by "x")

so clearly, the outpu will be
B B UB UB