CODEWITHSUNDEEP
uml
Daniel Clark
Daniel Clark

Reputation: 13

Multiple members of the same type: how to represent in UML class diagram

I can't seem to find this existing question but feel free to point me to it.

Imagine the following situation of a familiar fairy tale:

 ------------            -------------
|    Bear    |--------<>|  BearHouse  |
|------------|          |-------------|
|+name:string|          |+mama: Bear  |
 ------------           |+papa: Bear  |
                        |+baby: Bear  |
                         -------------

I just want to be sure my class diagram is accurate, or at least more meaningful.

Thank you

Upvotes: 1

Views: 1912

Answers (2)

qwerty_so
qwerty_so

Reputation: 36333

Rather than properties use named associations:

enter image description here

Probably a multiplicity of 1 for papa and mama and 0..* for baby would be fine (though in these times there's also possible to have papa or mama as 0..2 and for Mormons mama to be 1..*)

Regarding composition: better you forget this nasty concept. It does not bring real added value and only causes fruitless discussion about its need. Just use associations with multiplicity. Composition/aggregation can be used in certain database design concepts and (what's not really needed today) in memory management concepts.

Upvotes: 2

www.admiraalit.nl
www.admiraalit.nl

Reputation: 6099

I would assume a BearHouse is not 'composed of' Bears, but only serves as one possible location of Bears. I would use neither aggregation nor composition.

By the way, there is some redundancy in your diagram. The relationship says a BearHouse consists of Bears and the properties mama, papa and baby say that, in addition to that relationship, the BearHouse has a relationship with three Bears in particular.

Upvotes: 1

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