Association vs Dependency (Offbeat)

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Association vs Dependency (Offbeat)

Association vs Dependency (Offbeat)

2003-12-30 - By ashraf galal

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Reply: 1 2 3 4 5 6 7 8 9 10 >>

<html><div style='background-color:'><DIV>
Actually, these concepts is UML not a
  java.  You are quite
well understanding but I would like to illustrate the difference between them
and give an example. 
 <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com
:office:office" /><o:p></o:p>
Dependency :
Anytime a class uses another class in some fashion, a dependency exists
between the two.
A dependency exists of a class: 
-   
      has a reference to an object
directly.
-   
      Has a local variable based on
another class.
-   
      Has a reference to an object
indirectly via some operation parameters.
-   
      Uses a class�s static
operation
Also there are dependency between packages. 
 <o:p></o:p>
Association: 
There is two types of association, unidirectional and bi-directional
associations. 
Unidirectional association implies that an object of the class may
invoke methods on the other class.
In java, this manifest itself as an instance variables on the class that
may invoke methods. 
 <o:p></o:p>
Example: 
Public class customer
 {
   ?.

   Public Address
homeAddress;
 <o:p></o:p>
   ��

    }
 <o:p></o:p>
public class Address {
?..
}

 
bi-directional association means that either object in the association
may invoke methods on other.
In java, this results in an instance variable on each class based on the
type of the other class.
 <o:p></o:p>
Example;
Public class Team  
   {
     LinkedList  teamPlayers = new
LikedList();
      teamPlayers.add(new teamPlayer(?));
      
��?  }
 <o:p></o:p>
  public class
teamPlayer {
    Team  memberOf; 
     ?.
 } 
 <o:p></o:p></DIV>
<DIV>Ashraf Galal (416)804-8359</DIV>>From: ShriKant Vashishtha
<SHRISUBS@(protected)>>Reply-To: An interest list for Sun Java Center J2EE
Pattern Catalog <J2EEPATTERNS-INTEREST@(protected)>>To: J2EEPATTERNS
-INTEREST@(protected) >Subject: Association vs Dependency (Offbeat) >Date
: Sun, 28 Dec 2003 14:17:03 -0800 > >Hi All, > >I am slightly
confused in finding the difference between association and dependency. > &gt
;For me, whenever the variable is intialized at a local scope or passed as a
parameter in a method, its denoted as dependency. However, for association, I
believe, the object needs to be on global scope (as an instance variable).
However, I rarely use any object at a global scope, unless I know that it is
used for maintaining the state of class or need to be used across different
methods. So most of the time, I end up with dependency . > >Am I missing
something over here. > >Thanks >-ShriKant > > >-- ---- ---
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