when do we draw association?
Class Engine has "start(c:Component)" method. So do we need to draw an as开发者_如何学JAVAsociation between Engine and Component Class IF there is no "new Component()" inside Engine class.
No, you do not in general need to have an association to a type even if the type is mentioned in a parameter. It entirely depends on if the state of an Engine maintains a relationship with one or more Components.
If the Component you passed around is only use locally in method start
, then there is no real association that persists from one state (one method call) to the next.
This is not an association, it´s a dependency relationship between the two. A dependency means that if the dependee (the Component in your case) changes the depender (the Engine) may become affected (maybe Engine::start was using a Component method that it is no longer available or that has changed its parameters)
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