Difference between association and navigation

[s-peiran]

Definition of Navigation from the textbook:

Definition of Association from the textbook:

If both association and navigation requires one class to keep a reference to another class, then what differentiates them?

[TeeRenJing]

I think every association between two objects/classes has a navigability (Unidirectional or Bidirectional), and you can choose to include this information by adding arrowheads in the UML diagram. So I think navigability is a trait of the association, not something different from an association.

Much like how a road can be one way or two way.

[damithc]

Much like how a road can be one way or two way.

Good analogy @TeeRenJing 👍

[s-peiran]

@TeeRenJing thanks for chiming in.

[s-peiran]

I want to follow-up this qn that whether navigability and association arrows can be used interchangeably. Taking the practice exam for instance, can all the navigability arrows (such as that from activity to watcher) be replaced with association arrows?

[damithc]

Taking the practice exam for instance, can all the navigability arrows (such as that from activity to watcher) be replaced with association arrows?

@s-peiran There is no such thing as an association arrow. Association is the line ____, navigability is the arrowhead >

[s-peiran]

I meant whether it is technically correct to show navigability as association line? The navigability arrow is just a more specific representation of association that shows the direction of reference.

[damithc]

I meant whether it is technically correct to show navigability as association line? The navigability arrow is just a more specific representation of association that shows the direction of reference.

Think of navigability, multiplicity, association label, and association role as additional information you add onto an association. They don't exist without an association.

[s-peiran]

thank you for the clarification prof.