association owned by classifier and association owned by relationship in UML

Chriss

I hope this simple example helps.

Guess you have a Java class

public class A {
   private B b;
   ...
}

In UML you would model this relationship as an association from A to B:

A -> B

with the following modeling elements:

Class B
Class A
  + Property b : B [0..1]    (owned by the class)
Association A_to_B
  + Property from_a : A [1]  (owned by the association)

Where the association A_to_B would have 2 association (member) ends referring two the properties showed above (A::b and A_to_B::from_a):

Now, let’s think the following situation

public class A {
   private B b;
   ...
}
public class B {
   private A a;
   ...
}

In UML, you could the model the association (navigable in both ways) between A and B:

A <-> B

Whose model elements would be:

Class B
  + Property a : A [0..1]  (owned by the class)
Class A
  + Property b : B [0..1]  (owned by the class)
Association A_B

Where the association A_B would have 2 association (member) ends referring the two the properties showed above (A::b and B::a).