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Assume that:

  • Class A has a collection of Class B (aggregation/composition)
  • Class C accesses the interface of Class A to obtain specific instances of Class B
  • Class C manipulates/uses the interface of Class B instances it gets

It follows that without a doubt, Class C has a relation with Class A. However one question remains: Should a relation be mapped from class C to class B, and why?

Mogsdad
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Philippe Hebert
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1 Answers1

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Yes, you should have the usual association (arrow) from C to B. Because having association means C have navigation from C to B.

As C can manipulate with B instances, the navigation from C to B also exists, and the back arrow is also necessary.

As the association works both-side, both arrows should not be shown. The contemporary UML standard does not use drawing of two-sided arrows.

If C has also fields (not local variables!) of type B, the C-B line should have the point on the B end. The same for the back direction. Look for examples here

Community
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Gangnus
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