title: UML class diagram Association vs ( Aggregation | Composition )-Diamonds
body: <p>I am not sure if I do use the <a href="http://en.wikipedia.org/wiki/Class_diagram" rel="nofollow">association and aggregation or composition diamond</a> properly. </p>
  
  <p>I would use the Association for interfaces, because I can't instantiate them. Like they do it <a href="http://sourcemaking.com/design_patterns/builder" rel="nofollow">here</a> for example. Or for static classes, same reason.</p>
  
  <p>And the diamonds I use only for objects I can instantiate. Like normal classes.</p>
  
  <p>But I am not sure if this is the correct way to differentiate them, because if you <a href="http://en.wikipedia.org/wiki/Class_diagram" rel="nofollow">check</a> again, you will see they aren't so specific about it. In the UML 2.3 <a href="http://www.omg.org/spec/UML/2.3/" rel="nofollow">specification</a> I couldn't get out more, so how are you using it?</p>
  
  <p>And there is a third manner, the dashed lined &lt;> arrow, but I don't have a glue when to use this one. So maybe you can help me with that one, too?</p>