Finding Relationship among Classes

A Relationship may belongs to more than one Relation type at same time.In this case our answer should be the Strongest among them.

Dependency --> Association -->Aggregation--> Composition
-------------------------------------------------------------->
Strongness

For Example a relation b/w class A and B is as follows.
Dependency and Association and Aggregation and Composition

So in this case our answer should be Composition .




Now let's See how to Find Relationship among Classes:

1. If Class A is related to class B by any means there is dependency b/w class A and class B.


Eg:class A:


class A
{


void methodA( B b, int i )
{
System.out.print("i am B");
}


}

2. Now apart from Dependency a relation may be of type Inheritance or Association.

a> If there is any keyword 'extends ' is being used to relate these classes than it would be "Inheritance".

b> Else if class A Contains or Stores object of class B it would be "Association".

Else it would be only "Dependency".


3.If it is Association than

a> if Object of Class B is being created in Class A it Composition.


b> Else Object of Class B is passing as Parameter in any function of Class A
it is called "Aggregation ".


Here are some Examples to make things clear.

What is the relationship b/w class A and class B ?

class A {

public void methodA() {

B b = new B();

b.methodB();

}

}

class B {

public void methodB() {

}

}



Ans.1 Dependency

What is the relationship b/w class A and class B and b/w class A and C ?


Class A
{

private B b;


method( C c , int num);

}



Ans.2

Relationship between A and B is Association.
Relationship between A and C is Dependency.

Note: There is not any Difference b/w Association and Aggregation/Composition at Impementation level.


Note: For Aggregation and Composition classes should have 'Part - of' relationship.

For Any queries leave your Comment.
- Agam Gupta.