when OO-designing...

Posted on 2002-03-31
Last Modified: 2013-12-03
I'm new to OO- design.
I've had some Relational experience.
I'm confused.

For example, when I design classes which one is the better?

I have three classes called, CUSTOMER,ORDER,PRODUCT.
CUSTOMER have three attributes, customer_ID, customer_name, customer_address.
PRODUCT have three attributes, product_ID, Product_name, Product_price

First option of ORDER is
class ORDER {
   string order_code;
   string product_id;
   string customer_id;

The other is as follows.
class ORDER {
   string order_code;
   Product _product;
   Customer _customer;

In relational database design, when you design n:n relationship of two entities the relational entity comes around like,

when customer orders products customer,

cardinality n:n
intermediate table(order) comes out.
so we can use the PK of two tables(product,customer) as FK of the ORDER table.

Are there criteria like above in OOAD?

Question by:iamjhkang
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions

Expert Comment

ID: 6911010
Well.. ya only need to learn Associattion and bit about Composition or say containment theory n you will be able to solve your problem.. i couldn't suggesti ne thing.. cuz this is the basic problem when one comes from a  relational background to OOP .. its better to learn about what i mentioned above.. n you would be having a fair idea of such Entity Relations.. in OOD.. by they way these are kinda basics so ya must go through to these topics

Author Comment

ID: 6911286
Yes. It's basics.
I know relationships between classes, association and composition.
You know basics, I want experts's comments on the basics.

Accepted Solution

Ovi earned 120 total points
ID: 6912208
From the OOP design point of view, modeling a such "system" is like in real world. Of course you can model in any way you want, but the essance of OOP is modeling real live objects to programming models. So in my opinion if you analyze the sentence : Customers order Products, you have two fine defined and stable entities : Customer and Product. Ordering is an action which links those two entities one to another. Now this order action can be broken in many types of ordering. The base structure of an order is a customer id and productS idS (a customer can order at least one product). So the design of Order class should by in my oppinion :
class Order {
  private String orderId;
  private String customerId;
  private String[] productIds; //or Vector of product idS

If you want to implement in future different kind of orders I suggest to create the above class as abstract, and use different order types as derivate classes of this one. In this way you will respect most of the OOAD principles.

If you are realy interested into some OOAD principles you should follow this link : section "Design Principles"

Expert Comment

ID: 6915967
ADMINISTRATION WILL BE CONTACTING YOU SHORTLY.  Moderators Computer101 or Netminder will return to finalize these if still open in seven days.  Please post closing recommendations before that time.

Question(s) below appears to have been abandoned. Your options are:
1. Accept a Comment As Answer (use the button next to the Expert's name).
2. Close the question if the information was not useful to you, but may help others. You must tell the participants why you wish to do this, and allow for Expert response.  This choice will include a refund to you, and will move this question to our PAQ (Previously Asked Question) database.  If you found information outside this question thread, please add it.
3. Ask Community Support to help split points between participating experts, or just comment here with details and we'll respond with the process.
4. Delete the question (if it has no potential value for others).
   --> Post comments for expert of your intention to delete and why
   --> You cannot delete a question with comments, special handling by a Moderator is required.

For special handling needs, please post a zero point question in the link below and include the URL (question QID/link) that it regards with details.
Please click the Help Desk link on the left for Member Guidelines, Member Agreement and the Question/Answer process for further information, if needed.

Click you Member Profile to view your question history and keep them all current with updates as the collaboration effort continues, to track all your open and locked questions at this site.  If you are an EE Pro user, use the Power Search option to find them.  Anytime you have questions which are LOCKED with a Proposed Answer but does not serve your needs, please reject it and add comments as to why.  In addition, when you do grade the question, if the grade is less than an A, please add a comment as to why.  This helps all involved, as well as future persons who may access this item in the future to seek help.

To view your open questions, please click the following link(s) and keep them all current with updates.

------------>  EXPERTS:  Please leave any comments regarding your closing recommendations if this item remains inactive another seven (7) days.  Also, if you are interested in the cleanup effort, please click this link

Moderators will finalize this question if still open in 7 days, by either moving this to the PAQ (Previously Asked Questions) at zero points, deleting it or awarding expert(s) when recommendations are made, or an independent determination can be made.  Expert input is always appreciated to determine the fair outcome.
Thank you everyone.
Moderator @ Experts Exchange

Author Comment

ID: 6926861

Featured Post

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Java contains several comparison operators (e.g., <, <=, >, >=, ==, !=) that allow you to compare primitive values. However, these operators cannot be used to compare the contents of objects. Interface Comparable is used to allow objects of a cl…
Introduction This article is the second of three articles that explain why and how the Experts Exchange QA Team does test automation for our web site. This article covers the basic installation and configuration of the test automation tools used by…
Viewers learn about the “for” loop and how it works in Java. By comparing it to the while loop learned before, viewers can make the transition easily. You will learn about the formatting of the for loop as we write a program that prints even numbers…
Viewers will learn about basic arrays, how to declare them, and how to use them. Introduction and definition: Declare an array and cover the syntax of declaring them: Initialize every index in the created array: Example/Features of a basic arr…
Suggested Courses

626 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question