Association vs Dependency (Offbeat)

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Association vs Dependency (Offbeat)

Association vs Dependency (Offbeat)

2003-12-30 - By ShriKant Vashishtha

Back

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

Hi Ashraf,

I am quite clear regarding unidirectional and bidirectional association.
But could you please elaborate the following points more, may be with some
examples.

- has a reference to an object directly.
- Has a reference to an object indirectly via some operation
parameters.

Thanks
-ShriKant

ashraf galal <ashrafwg@(protected)>
Sent by: An interest list for Sun Java Center J2EE Pattern Catalog
<J2EEPATTERNS-INTEREST@(protected)>
12/29/2003 11:22 PM
Please respond to An interest list for Sun Java Center J2EE Pattern
Catalog

To: J2EEPATTERNS-INTEREST@(protected)
cc:
Subject: Re: Association vs Dependency (Offbeat)

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"
/>
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
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.

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 >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 > > >-- ---- --- -- ---- ---- ---- ---- >Do you Yahoo!?
>Protect your identity with Yahoo! Mail AddressGuard >
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 Hi Ashraf,
 
 I am quite clear regarding unidirectional
and bidirectional association. But could you please elaborate the following
points more, may be with some examples.
 
 -         has a
reference to an object directly.
 -         Has a
reference to an object indirectly via some operation parameters.
 
 Thanks
 -ShriKant
 
 
 
<table width=100%>
<tr valign=top>
<td>
<td>ashraf galal <ashrafwg@(protected)>

 Sent by: An interest list for Sun Java
Center J2EE Pattern Catalog <J2EEPATTERNS-INTEREST@(protected)>
12/29/2003 11:22 PM
 Please respond to An interest list for Sun
Java Center J2EE Pattern Catalog
 
<td>        
         To:   &nbsp
;    J2EEPATTERNS-INTEREST@(protected)
         cc:   &nbsp
;    
         Subject:  
     Re: Association vs Dependency (Offbeat)</table>
 
 
 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" />
 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 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. 
  
 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 &nbsp
;teamPlayers = new LikedList();
       teamPlayers.add
(new teamPlayer(…));
        …&
#8230;…  }
  
   public class teamPlayer {
     Team  memberOf; 
      ….
  } 
  
Ashraf Galal 
(416)804-8359
 >From: ShriKant Vashishtha >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 > >
>-- ---- --- -- ---- ---- ---- ---- >Do you Yahoo!? >Protect your
identity with Yahoo! Mail AddressGuard > >===============================
====================================== >Companion Site: http://www
.corej2eepatterns.com >J2EE BluePrints: http://java.sun.com/blueprints
/corej2eepatterns >List Archive: http://archives.java.sun.com/archives
/j2eepatterns-interest.html >Unsubscribing: email "signoff J2EEPATTERNS
-INTEREST" to listserv@(protected) 
 

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