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:'>Hi
Vipul <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office"
/><o:p></o:p>
Dependency example: <o:p></o:p>
If you have a java class like: <o:p></o:p>
 <o:p></o:p>
Public class  abc implements  abcController<o:p></o:p>
 <o:p></o:p>
{<o:p></o:p>
?.<o:p></o:p>
}<o:p></o:p>
 <o:p></o:p>
class abc implements abcController
(interface) this is a sort of dependency.<o:p></o:p>
 <o:p></o:p>
Also dependency between packages.<o:p></o:p
>
 <o:p></o:p>
If these examples are not clear let me know
and I can provide more examples.<o:p></o:p>
 <o:p></o:p>
The answer to your second question is yes
class Address can stand alone without class Customer, and can exist without
class Customer but class Customer cannot exists without class Address exists.
 <o:p></o:p>
 
<DIV>Ashraf Galal (416)804-8359</DIV>>From: "Gupta, Vipul" <VIPUL.GUPTA
@(protected)>>Reply-To: An interest list for Sun Java Center J2EE
Pattern Catalog <J2EEPATTERNS-INTEREST@(protected)>>To: J2EEPATTERNS
-INTEREST@(protected) >Subject: Re: Association vs Dependency (Offbeat) &gt
;Date: Tue, 30 Dec 2003 11:00:54 +0530 > >Hi Ashraf, > >CAn u
provide a simple example for dependency as well. > >Secondly, In
Association - does it mean the instance of the class can be >created
independently. >Meaning, in the example >Example: > >Public class
customer > > { > > .... > > Public Address homeAddress; >
> > > ...... > > } > > > >public class Address { >
>..... > >} > > > >Does it mean that the Address class can
exist without the customer class or >Address class will exist only if
Customer class is there. > > > >Regards > >Vipul > >--
---Original Message-- -- >From: ashraf galal [mailto:ashrafwg@(protected)]
>Sent: Tuesday, December 30, 2003 10:52 AM >To: J2EEPATTERNS-INTEREST@(protected)
.SUN.COM >Subject: Re: Association vs Dependency (Offbeat) > > > &gt
;Actually, these concepts is UML not a java. You are quite well &gt
;understanding but I would like to illustrate the difference between them and
>give an example. > > > >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. > > > >Association: > >There is two types
of association, unidirectional and bi-directional >associat
ions. > >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. >
> > >Example: > >Public class customer > > { > > ....
> > Public Address homeAddress; > > > > ...... > > }
> > > >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. > > >
>Example; > >Public class Team > > { > > LinkedList
teamPlayers = new LikedList(); > > teamPlayers.add(new teamPlayer(...));
> > ......... } > > > > public class teamPlayer { > >
Team memberOf; > > .... > > } > >
> >Ashraf Galal >(416)804-8359 > >From: ShriKant Vashishtha &gt
;Reply-To: An interest list for Sun Java Center >J2EE Pattern Catalog >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. > >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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