I am currently building a class diagram on PlantUML. I have 2 classes having 2 associations class. While adding a third association class, an error message is displayed with "Cannot have more than 2 associations". Is it a limitation of PlantUML? I am pretty sure than a lot of big class diagram may have more than 2 association classes for the same classes.
Here is the error on the online editor: http://www.plantuml.com/plantuml/uml/SoWkIImgAStDuKhEIImkLd3CoKnELQYkXNATyfD072w8iAwk7KY4ImFCrG6nDHNqz1Hy4ukICGIzKXFpyb8nX5sBCfEv75BpKe1s0W00
Anyone?
Related
Just a simple question: I'm working on a class diagram for a dynamic web site for my internship. I have an association between two classes (client and article), the relation is many to many.
Normally I have to add an association class between them, but I don't want to because the client can only read the article's writing on the web page, and he cannot post. Is it correct if I don't draw the association class on the diagram?
There is no need to add association class only due to many to many relationship. The association class is needed when you have an association that at the same time is also a class, i.e. has some properties on its own.
You can use simple association with any multiplicity on any of the ends including having * on both ends.
when I convert the above ERD into Class Diagram classes, I noticed the classes as below.
student
lecturer
module
user
I need to know how to convert "LecturerHasModule" and "studentHasModule" entities into classes. I'm confused to select their attributes.
The more logical seems to have a class-association between Module and Student and between Lecture(r) and Module
Impossible to answer you about teacherHasModule because it does not appear in your question (may be a typo for LecturerHasModule)
So, I'm trying to get better with labeling my class diagrams and wanted to know if I have laid out the class diagrams here in the correct fashion. I've tried adding in an abstract class for Blood Pressure as both classes have similar methods which both can implement.
Edit: After a few changes the current design of the diagram is as following:
abstract class for Blood Pressure as both classes have similar methods which both can implement.
in that case you have that :
or that :
(I hidden class compartments to not have to enter the members)
There is no standard/normalized stereotype AbstractClass (nor abstract), the class have the attribute isAbstract and if it is true the name is drawn in italic as you did
I've started using the website draw.io, I want to create a class diagram but I couldn't find how to create an association class, any help would be useful. Thanks.
draw.io is a drawing tool, not a UML tool.
As such you can simply draw two class shapes, connect them with an association shape, then draw a third class as you association class and then use an association shape to connect you association class to the association.
Then go into the properties of the last association shape and change the line style to dashed.
Now it looks like a valid UML Association class, but I think you should really opt for a real UML tool instead of a drawing tool when you want to do anything with UML. Using this tool is similar to writing Java with MS Word.
The accepted answer is far to be perfect. In Draw.io (now called Diagrams.net), you can connect two shapes (here classes) with a connector but you cannot connect two connectors together.
Consequently, with the given solution, it will look like an association class but the dashes will not be really adjusted :
And really worste, if you need to re-arrange your diagram, the association link will not move and you will have to re-adjust it manually :
So, as it is sadly not possible to have a 100% satisfying solution for an association class, another solution is to turn the association class as a regular class. Here in the example, the OrderLine class is associated with both Order and Product classes. It is worth to note the migration of the multiplicities. Refactoring a class association as such an association will ALWAYS lead to have a 1 multiplicity for the non-association classes (here Order and Product), and the original multiplicities will be moved to the association class (here OrderLine).
What kind of UML diagram is this?
(source: tripod.com)
This is a class diagram, with added stereotypes
This is Class Diagram in a very abstract or initial form because all relationship are shown as Association.
Usually we start with such class diagram and then keep on refining by converting association (arrow as shown above) into more stronger relationship like generalization,composition,implementation etc.
Association is considered as weaker form of relationship between classes. So final class diagram should have fewer associations.
What is the emphasis or goal of this diagram? If it's the classes and relationships, then it's a class diagram. If it's the mapping between the classes and layers of function or responsiblity in the system, then it looks like a layer diagram. Those columns look like layers: presentation, business logic, data...
Ok now I see the problem after a good sleep :-)
It seems it is a powerpoint and not a class diagram because you can not have straight line in a class diagram. I mean you can not have 3 separators like Presentation/ objectos .......etc
This powerpoint tried to use class diagram and have added titles in order to separate 3 layers. The problem is that the class diagram is incorrect and it is not because you present it with 3 layer that it would become correct !! This is a bad understanding of what means JPA stereotypes inside a class diagram.
It looks like a Class Diagram that uses "swimlanes" on the background to facilitate some kind of MVC.
This class diagram is not correct because there is confusion between Java EE stereotypes and class names!
What are the << class module>> , << module>> stereotypes and Session, Session persistence names should be Java EE stereotypes. If it persists in the database then it is an entity! Persistence etc...can be written on attributes.
This diagram doesn't make sense!
The main advantage of scheme in this diagram is that if you use a code generator such as AndroMDA, MIA software or Blue Age, then you can then generate your database directly from the model. These tools look at stereotypes during code generation.
If you don't want to generate code from a model but prefer to let hibernate mapping do the job, then the "entity" stereotype can be written as an annotation in your java code. Then thanks to live code and model synchronization, hibernate can take the annotation and produce a mapping.
This is why stereotyping is really very important and using the wrong stereotype can be a very serious mistake!