AmitKumar Jain

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since Jun 13, 2005
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Recent posts by AmitKumar Jain


Thanks Devaka,

Your exam simulator is really cool. Although I didn't manage to find time to give it's mock exam,
I did have a look at it just the night before the exam. And I felt Ah! I should have given some
exams on it as well.

Well, I will definitely use it for other exams.

Amit.
8 years ago
Hi Ranchers,

I am back with a bang. I gave my first SCJP exam in 2005 and now I have upgraded it to
SCJP6 scoring 95% in the upgrade exam.

Although I scored 95%, I found some of the questions really tricky and I was even nervous
for a moment! And I feel happy about it ! I am glad that Sun really believes in testing
our skills.

As I have always said after previous certifications and I again say, it is the journey through
which we go through during the preparation is more important than the result.

As far as SCJP6 is concerned, I never knew so many new features (which come with their
own traps) have been added to Java6 as compared to 1.4, until I started preparing for
SCJP6.

But again, I give credit to Kathy and Bert for their wonderful book, for making the difficult
things appear easy.
Also, the mock exams provided with the book were great.
I did face problems while reviewing my answers in LearnKey software, provided with the book,
as it only shows the correct options for the questions.
I expected it to show me the correct options against the answers actually marked by me.
(sort of view whereby wrong answers are striked off and right ones are ticked off)
Also, the study guide option does not list all the options for questions (lists only correct ones),
making me to revisit the exam window to check for options.
I hope this can be improved in future.

Most difficult topics during the journey were Autoboxing,APIs and of course Generics.

Another topic which I found tough on SCJP6 was Coupling and Cohesion(OO concepts).
Although it is a small topic and exam has 2 or 3 questions on it, I always falter on it.
I faltered on it during mock exams and even in real exam.
I was even not convinced by the reasoning given against correct answers during
K & B mocks.
I feel the K&B book should have additional material on this topic( with examples).

Lastly, I say the overall journey towards SCJP6 was great.
As I say this,I still wonder about the journey of those who created Java6 and of course SCJP6.

When I will reach my office tomorrow, I will definitely feel a bit elated as compared to my colleages,
who are not aware of the richness of Java6.

Regards,
Amit
8 years ago
Hi Bob,

" For me two different references are different even if they point to the same object...."

Java always talks of references having a value which is a handle to an Object.
[ although the value is not known to us ]
Hence, when two references refer to the same Object, they are considered having the same value.

Even when we talk of Pass By Reference in method invocations, we say that copy(value) of
the reference is passed. Hence it is often said, "In Java, references are passed by value".

Amit.
Hi Bob,

I disagree slightly. Though you are correct, the statement requires correction.

== in case of references, checks whether the references point to the same object.
[ == in no way can compare objects , it just compares the references , which are
nothing but object handles ]

Amit

Hi Kamal,

Do you still have the voucher or it is already sold?
What is the expiry date in case not sold.

I am from Delhi and wished to appear.

Amit.
9 years ago
I think we need to promote EJB3 more than EJB3 in Action, as the latter will benefit automatically.
EJB Technology has been replaced by Spring & Hibernate in most organizations.
We need to bring back the confidence of industry back to EJB Technology.

In this regard, I feel "EJB3 in Action" will play a vital role.
Hence I thank Debu Panda, Reza Rahman & Derek Lane for their new book.

Industry won't accept EJB3 unless their are quality professionals trained in EJB3 and I hope EJB3 in Action will assist in this regard.
I missed that point on Pg 102 in HFEJB....

But I went through the spec again today...

On Pg. 91,92 ... section 7.9.1... the Object Interaction Diagram clearly shows that bean instance is not created when client calls create. Why isn't it specified there that this scenario may vary on Container implementation by a Vendor?

cheenu.. can you tell me where else it is mentioned in the spec?
I had read during my SCBCD certification that Stateless session bean instances are created during server startup and NOT when client calls create on the bean.

However, when I tested this functionality in Bea Weblogic and IBM Websphere Application Servers, then I found that ejbCreate() and setSessionContext() were called only when I invoked a business method on the bean.
Does this prove that this is server specific and has to be configured and is not mandated by the specification??

I had to face embarrassment due to this during an interview.
From EJB spec Pg 352

Containers may optionally support the use of the NotSupported, Supports, and Never
transaction attributes for the methods of entity beans with container-managed persistence
because the use of these transaction modes may be needed to make use of container-managed
persistence with non-transactional data stores
. In general, however, the Application Assembler
should avoid use of the NotSupported, Supports, and Never transaction attributes for
the methods of entity beans with container-managed persistence because it may lead to inconsistent
results or to the inconsistent and/or to the partial updating of persistent state and relationships
in the event of concurrent use.



I hope this is clear now..
Amit
ejbSelect vs ejbFind

1) ejbFind methods are exposed to client through home interface.
ejbSelect methods cannot be exposed.
i.e ejbSelect method can be used internally by the EJB's business
methods.

2) ejbFind can only return reference to Component Interface (Single Entity
Finder) or Collection of references to Component Interface (Multiple
Entity Finder )
ejb Select method can return any RMI-IIOP compliant value in addition
to above.

3) ejbFind methods are always executed by a bean in pooled state while an
ejbSelect method can be executed by a bean in pooled state(through
ejbHome business methods) as well as in ready state( through Business
methods ).

4) (w.r.t CMP Entity Bean)
ejbFind methods need not be implemented by the Bean Provider in bean
code. However Bean Provider has to provide an abstract definition of
ejbSelect in the bean code.

Regards,
Amit
Hi Ranchers!

Its a fact that statefull session beans cannot be passivated while in a transaction while an enity bean can.
Can any one tell me why this is not allowed?

I tried to search on almost all java forums but didn't find answer anywhere.

However, my point of view is that there may be some performance issues here.. like before passivation , the statefull session beans needs to close the open connections and re-aquire them when it is activated..

Regards,
Amit
I also agree with Prakash... local or remote depends on whether or not EARs are deployed in same JVM or different JVM.

However, the given answer can be true only if each EAR gets a different instance of JVM... I don't know whether this happens... I'm just guessing...
Congrats !!! Great Score...

11 years ago