方法参数的UML图

Question

Let's say I have the following code:

class A {
public:
    void doSomething(B* b);
}

class B {
}

How would I describe this in a UML diagram? My first thought is that A uses B, so there should be a dotted line from A to B. But in some of the school papers (this is a very tiny part of a school assignment report) they seem to use the aggregation symbol (empty diamond and solid line).

That doesn't seem right to me - if A actually contained a pointer to B as a member, that seems right. But when only some methods use a pointer to B, and don't store it in any member variables, it seems wrong.

What's right here?

(I could ask my teachers but they usually take really long to respond to this type of question... and honestly, I trust the collective brain trust of Stackoverflow more :) )

Answer 1

You should use a simple dependency between A and B:

A does just use B as parameter in an operation. If you have some attribute of type B then you would use an association. Aggregation give only a little extra semantics and you can (/should) leave it out unless you know that you want to transport some specific information.

Answer 2

There should NOT be any arrow between class A and class B . Arrows between classes are used to indicate "associations".

An association indicates that the system you are developing stores links of some kind between the instances of the associated types.

Source: Properties of associations on UML class diagrams

To capture/represent void doSomething(B* b); you might try using activity diagram, for more see this link .