A class diagram describes the structure of a system by showing the system's classes, their attributes, operations (or methods), and the relationships among the classes.

learn more… | top users | synonyms

22
votes
4answers
44k views

UML class diagram notations: Differences between Association, Aggregation and Composition

I'm confused about some of the notations of UML class diagrams. Pretty sure I know what Association means. Any relationship between instances of two classes, where an instance of one class needs to ...
7
votes
2answers
23k views

What does the arrow mean in a Class Diagram?

I need help trying to understand what the meaning of the arrow in a UML Class Diagram is, more specifically in this Composite Diagram. What's the difference between the simple line (from a class to ...
6
votes
1answer
515 views

How to display in compositional relationship that the item knows about the container?

I'm drawing a class diagram and noticed that sometimes I got a relationship (composition or aggregation) where the item uses the container, and sometimes not. What is the visual difference in a ...
6
votes
5answers
7k views

How to Model a simple file-system by UML class diagram

I want to model a file system which contains both files and directories, and directories can contain either files or other directories. This is what I have reached so far: In OOSE book, however, a ...
5
votes
3answers
7k views

How do you annotate instantiation in UML class diagrams?

Given this pseudo code: class B { } class A : B { int val; }; alpha = new A(); What arrow do I draw between alpha and A in a UML class diagram? Is this even something UML is meant to do? +---...
4
votes
3answers
959 views

How bad is it to have two methods with the same name but different signatures in two classes?

I have a design problem related to a public interface, the names of methods, and the understanding of my API and code. I have two classes like this: class A: ... function collision(self): ...
4
votes
2answers
3k views

Java code generation from class diagram

I'm on the way developing a Java application where user can provide a class diagram and get the corresponding Java code. I don't know how can I let the user interactively draw a class diagram in Java....
4
votes
1answer
210 views

How to correctly draw a UML class diagram with fully qualified association?

Given the following code I have to draw the corresponding class diagram: public class Shop { List<Client> clients; Storage store; User chief; Set<Invoice> invoices; } ...
3
votes
5answers
2k views

What classes to put exactly in a class diagram?

What classes must I put in a class diagram? Only classes used in Business Layer and associations between them? Or also other classes in the Data Access Layer, Service Layer, etc.?
3
votes
1answer
197 views

How to draw a class diagram where a class contains either 6 other classes or mupltie different

I know the basics but do not how to model this (it is an exercise with no solution provided): An order can contain 1 or more cartons of beer. Each carton contains 6 beers of the same kind but ...
2
votes
3answers
2k views

Should we include external systems in Class diagram?

I want to draw a class diagram that shows the following for an application: An external content management system that publishes some news items. The class that represents the news item in my ...
2
votes
3answers
448 views

How do I show 'creates' in a UML class diagram?

Let's say my code is going to look like this: public class MyController { private Foo foo; private FooGenerator fooGen; //setters public void work() { this.foo = this....
2
votes
1answer
2k views

UML representation of specific factory pattern

I have to create an UML class diagram from the following example code (Perl). I don't think that the standard factory pattern match in my case or I don't understand it correctly. I don't have ...
2
votes
1answer
3k views

What is the difference between UML Data profile and ER model?

I have been asked this question and even after a lot of research, I cannot find the answer. When I design a database using Entity relationship (ER) and then re-draw it as UML class model (extended ...
2
votes
2answers
274 views

How can I indicate if an object operates with another one in an UML class diagram?

Suppose I want to draw a class diagram of a DAO and an Entity. The DAO is used to load instances of the Entity from the database. How can I represent this relationship on my class diagram? Is this ...
2
votes
3answers
1k views

What to use in UML for included module in ruby?

I like to create simple class diagrams for my projects. Most of the time I just use composition, inheritence and associations. IMB's basic UML resource tells all about this. However I'm using ruby so ...
2
votes
1answer
195 views

How to manage coupling in model classes

I'm doing a class diagram for a game project, but I'm stuck on a coupling problem. Context The projet is a turn-based game. Two users are playing. They've got units on a map. They play until 1 ...
2
votes
2answers
887 views

Package diagram for an MVC patterned project?

We are required to make a package diagram for our senior project. Since our project uses MVC patter design, we created an MVC class diagram, now, our problem is in creating the package diagrams from ...
2
votes
1answer
99 views

Class diagrams and frames

UML class diagrams (1st pic) and frames (which belong to knowledge representation and artificial intelligence) (2nd pic) look pretty alike. But do class diagrams exactly type of frames or they just ...
2
votes
1answer
296 views

UML diagram for an existing implementation

I have some code, which I want to present in UML, but I've stuck at one point. Let me tell you something about code's functionality. I have a workspace in which I can place some Components, select ...
1
vote
3answers
45 views

How to represent the following scenario in a class diagram?

Consider a store with multiple branches and a system generates reports for each branch monthly and annually and an overall report as well monthly and annually. So in total there are 4 types of ...
1
vote
1answer
553 views

I want to draw class diagram, but I don't know how to put server and database inside? [closed]

I just started to draw class diagram, I think it is based on 3-tie architecture. I have mobile application, servers, database, and web interface. But I do not know if it should put the server in? I ...
1
vote
4answers
4k views

best way to handle a many to many relationship?

I am drawing a class diagram and I want to know what's the proper notation for many to many relationship between supplier and product? Should I show the table created supplier_product or leave it out ...
1
vote
1answer
196 views

Why do you reduce multiple inheritance to the diamond problem?

Whenever I read something like this: Many programmers exhibit a slight, involuntary shudder whenever multiple inheritance is mentioned. Ask them to identify the source of their unease and they ...
1
vote
3answers
310 views

UML Class Diagram: How can I represent “orthogonal” generalizations (or multi-inheritence)?

I try to represent in a UML Class Diagram the following object and features: The Object: A System (e.g. an electronic device) that can be of Type A, B or C If the System is of type A, it has a ...
1
vote
1answer
290 views

Should dependency relationships always be shown on class diagrams

I recently started using the Object aid UML generator plugin for Eclipse and noticed that by default adding of dependency relationships is switched off. This made me wonder if in most cases they ...
1
vote
3answers
913 views

UML - Class Diagrams Order -> Products

I have a class diagram that is like this: < Order > (1) CAN HAVE (M) < products > But therefore Order has the following: Order_Id Customer_Id Order_date_day Order_date_month ...
1
vote
1answer
133 views

Inheritance vs Class Diagram [closed]

What is the difference between an inheritance diagram and a class diagram in UML? For the Computer Science A Level (a British test administrated by Cambridge University, so it's possible that this ...
1
vote
2answers
883 views

How show Attributes which appear In Many To Many association

As we know a many to many association are shown by two asterisks in both end of association. Now I have a association between two entities "Good" and "Invoice" so Good and Invoice have a many to many ...
1
vote
1answer
60 views

Visibility notation in UML class diagrams

I'm reading about UML class diagrams and notation for visibility, and I can't tell if this book (Learning UML 2.0 by Russ Miles) has a typo or is just not explaining itself. Consider these two ...
1
vote
1answer
245 views

UML diagram for attributes that can have two different types

I have been to an interview for a financial programming job, and I could not answer to one question for sure. I thought about it again, but I really cannot find a good answer. They asked me to design ...
1
vote
1answer
583 views

How to represent a multiple choice attribute in UML class diagram?

I'm modelling a Filter class that stores the options for filtering a search. Some of the attributes are multiple choice. For example, if you are filtering hotel rooms you have a Price attribute that ...
1
vote
2answers
355 views

Confusion about associations in UML class diagram

--------------------- ---------------------- | FLIGHT | | STEWARD | --------------------- ---------------------- | Arrival time | | Steward ID | | ...
1
vote
3answers
249 views

What alternative is better to diagram this scenario?

I was creating and discussing a class diagram with a partner of mine. To simplify things, I've modify the real domain we're working on and made up the following diagram: Basically, a company works ...
1
vote
1answer
536 views

My UML class diagram is too complicated, what should I do?

Classes have 10-20 links with one another and you can't see anything in that mess of a diagram Unfortunately we finished coding already and if we change the class diagram we have to redo the whole ...
1
vote
1answer
2k views

Class Design and Structure Online Web Store

I hope I have asked this in the right forum. Basically, we're designing an Online Store and I am designing the class structure for ordering a product and want some clarification on what I have so far:...
1
vote
1answer
142 views

How to show link between a java class which gets JSON data from PHP script

I am trying to show the relationship that a java class has with a PHP script. The PHP script gets data from a database and then converts it into JSON format. This is then read by the java file. In my ...
1
vote
1answer
139 views

Finding methods of classes from the use case

I know some nouns in the use case scenario are candidate to be class, for example member, customer, student .... I can find such entities and some attributes of them, but my problem is that I can't ...
1
vote
1answer
507 views

How would you draw this UML class diagram?

I'm currently trying to learn UML but I have trouble with this one. Lets say you have a container with cards, a container with players, and that player has also cards. How would you draw this in a ...
1
vote
1answer
168 views

Class diagrams - do aggregated/composed classes automatically see each other?

Let's say that in the game, a player has a pet: Player<>------Pet Obviously player can access Pet's fields and methods, but I assume Pet does not know about the player? I need that Pet can access ...
1
vote
1answer
556 views

UML class diagram - can aggregated object be part of two aggregated classes?

Some sources say that aggregation means that the class owns the object and shares reference. Lets assume an example where a company class holds a list of cars but departments of that company has list ...
1
vote
1answer
2k views

UML Class diagram confusion

I am learning how to draw a UML class diagram and after reading a few tutorials, I am still confused about the appropriate usages of Association type (The clear diamond and black diamond). I ...
1
vote
1answer
502 views

How would you go about creating a class diagram for a JPA/JSF application

I was creating a class diagram for an application I was working on today and I didnt include the JPA entities since I had all the information I thought was important in my DAOs, for example, I just ...
1
vote
0answers
26 views

Shared pointers across threads in UML for class and sequence diagrams

How does one represent shared pointers across threads in UML for class diagrams and sequence diagrams? I especially want to document the ownership of the memory even though it's accessibility (a ...
1
vote
2answers
211 views

Can a UML class diagram show two different relationships between two classes?

I have a class which has an inner (nested) class. I have shown this relationship between the two classes in my class diagram. However, I am also using the inner class within the outer class... do I ...
0
votes
4answers
571 views

Does it make sense to generate java classes from class diagram?

As we do design & analysis before development, wouldn't be convenient to be able to generate Java classes from a class diagram? This would promote more exhaustive design and better codes, right? ...
0
votes
2answers
369 views

How to indicate that a class might implement an interface?

Say I have a class User and an interface Administrator. Some users are administrator and can thus implement the interface. Most aren't, however, so it's false to say that "User implements ...
0
votes
2answers
191 views

Subclassing to avoid line length

The standard line length of code is 80 characters per line. This is accepted and followed by the most of programmers. I working on a state machine of a character and is necessary for me follow this ...
0
votes
1answer
84 views

What is the UML idiom for classes that are too big to fit into one box? [duplicate]

I am documenting an existing system using UML 2, and a few of the classes are too big to comfortably fit into a single class box. So far, I've resorted to breaking up the class into multiple boxes ...
0
votes
3answers
99 views

Should foreign keys be represented directly when mapping database tables to classes? [closed]

Ok, in my database I have a table Event and a table Room. Each Room can have many Event. Room table roomID-roomName 1 - cafe102 ... Event table eventID- Time -type -roomID 1 - 11:20 - 1 ...