Inheritance vs Aggregation

[Prasath Thirumoorthy]

Hi Folks,

Polymorphism can be acheived by two means:
1.Inheritance is-a relationship
2.Aggregation has-a relationship

Inheritance is achieved by extending the existing class using the extends clause and Aggregation is by declaring a object of a class as a member in another class.

I need some clarifications on when and where to use inheritance and aggregation.

Please provide me with some examples and explanations.

Thanks & Regards,
Prasath T

[marc weber]

Originally posted by Prasath Thirumoorthy:
...Polymorphism can be acheived by two means:
1.Inheritance is-a relationship
2.Aggregation has-a relationship
...

Uh...

Originally posted by Prasath Thirumoorthy:
...I need some clarifications on when and where to use inheritance and aggregation...

In general, favor composition (has-a) over inheritance (is-a). If you have a need for polymorphism, then use inheritance. (But you're going to need to clarify exactly what polymorphism is before this makes sense.)

[marc weber]

This is an older article (from 1998), but the concepts are fundamental: Artima Developer - Composition versus Inheritance.