xjl xu

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since Feb 28, 2003
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Recent posts by xjl xu

How long is needed for people who have VERY LITTLE experience on Websphere Studio Application Developer to prepare for IBM 157?

Now we are looking at software, but we are looking at the interfaces of the software, not the implementation. Object-oriented development puts a great emphasis on the difference between interface and implementation, but this is often overlooked in practice because the notion of class in an OO language combines both interface and implementation. This is a shame, because the key to effective OO programming is to program to a class's interface rather than to its implementation. There is a good discussion of this in the first chapter of Gamma, Helm, Johnson, and Vlissides (1995). You often hear the word "type" used to talk about an interface of a class; a type can have many classes that implement it, and a class can implement many types.

does an interface of a class here stand for method definition or anything else?
Refer to the exhibit to answer the question.
Which of the following is the correct description of the sequence
diagram? When an instance of a:
a) Person is asked for its assets, it sums the balances of each of
its asset Accounts.
b) Customer is asked for its assets, it sums the balances of each
of its asset Accounts.
c) Person is asked for its assets, it returns the balance of its
asset Account.
d) Customer is asked for its assets, it returns the balance of its
asset Account.
Single Select - Please select the best answer (one and only one choice
must be selected).
i think b) is correct, since Customer is object and Person is class.
Am I right?
Thank you for your replay!
According to your replay, at least two question of them are wrong! the other one is not sure.
The problem is why my sample test question is different with the question provided by Liu Dong?
I think these kind of wrong question will mislead the tester.
Please see the following question:
Which of the following are TRUE about services resulting from use
a) New requirements in use cases generally result in one or more
public methods in a domain model class.
b) Private methods are required by the system's use cases.
c) Use cases drive the design of interaction diagrams, which in
turn define public methods in domain model classes.
d) Each alternative scenario of a use case generally results in a
new association between classes.
Multiple Select - Please select all of the correct answers (this
question has 2 correct choices).
a, c

As my understanding, we can not define
public methods in a domain model class. All options are wrong!

What, if anything, is WRONG with the following analysis use case?
Use case: Sell goods
Description: Accept tender from a customer, package products being purchased, and remove the products from inventory.
Actors: Clerk
Preconditions: Customer has chosen products to buy from inventory.
Postconditions: Products are no longer in inventory. Store cash balance is increased.

A.There are design details intermixed with the requirements.
B.The actor's actions and system responses are not separated.
C."Sell goods" is too broad to be a use case.
D.There is nothing wrong with this use case.
Where is the step?
I got the step from Answers to IBM 486 sample test provided by Don Liu.
1. The clerk scans the product codes on each item being purchased.
2. As each item is scanned, the system calculates a running total,
prints line items on a receipt, and displays the line items to the clerk on
the ReceiptPanel.
3. The clerk can remove items from the purchase by pressing the "Void
item" button.
4. ?
5. Once the customer has paid for the items, the items are removed from
inventory and the cash register balance is incremented by the total
amount of the good sold.
Why does the step not exist in MY SAMPLE TEST !
Which of the following are recommended when developing an OO system?

A.Write a description of the concept that a class represents whenever a new class is declared.
B.Use interfaces for types or roles that objects may play, independent of their location in the class hierarchy.
C.Apply design patterns where applicable in the system.
D.Name classes based on their design specifics, such as "array" or "queue".
Select the best answer.
It seems obviously that a), b) c) are right answers. but according to the question, I only can select one question. which one is the best one? Why there are 3 options in the Answers to IBM 486 sample test provided by Don Liu
Please help me!