class diagram question

I have 2 questions about class diagram. firstly if i have used an object of class A in my class B , in drawing the class diagram i should associate class A with B . or association is just u开发者_开发知识库sed when a class uses a method of the other class.

my other question is almost similar. if in class A i have a dictionary< class B, Class C> , then in class diagram should i associate the class A with B and C and say 'use'in connection?

In my view, in both cases it is a Dependency you show, not an Association.

In UML, the relationships tend to cover:

1. Dependency
2. Association
3. Generalization
4. Relization

In your case, the closest is a Dependency from Class A on B and C (represented with dashed line with arrowhead pointing to B and C). You're not directly associating (via aggregation or composition), you're not generalising A into B or C (or vice versa) nor are B or C realizing A (or vice versa).

If in doubt, I strongly suggest using a UML reverse-engineering tool and writing the source-code skeleton you know of, and see what it suggests. I use, but don't necessarily recommend, Enterprise Architect.

Associations are used when the A class "will" have an attribute of type B. I.e. at the UML level this is indicated using associations. At the code level, e.g. Java, these associations are transformed into attributes in the participant classes (one or two depending on the navigability properties of the association)