Determining IS-A & HAS-A Relationship when using Abstract Classes / Interfaces

[Ehsan Rahman]

Hi All,

Dog 'Is-A' animal.
Dog 'Has-A' dog collar.

However, is there any determination of IS-A or HAS-A relationship when using Abstract Classes?

  

abstract class DogBehaviour{
int barkLoudness = 5;
abstract void bark();
abstract void waggleTail();
}

public class RoboDog extends DogBehaviour{

bark(){
...
}

waggleTail(){
...
}

}

Q's:
- Does RoboDog 'Have-A' barkLoudness of 5?
- Does RoboDog 'Have-A' or 'IS-A' bark() ?
- What about Interface methods and static variables if RoboDog were to implement them? Would they be considered 'HAS-A' or 'IS-A'?

Links to articles would also be helpful please.

Thanks in advance,
Ehsan

[Vikas Kapoor]

Does RoboDog 'Have-A' barkLoudness of 5?
- Does RoboDog 'Have-A' or 'IS-A' bark() ?

Ehsan, you are misinterpreting the IS A and HAS A relationship. They are not comparable with state and behaviour of Class.
Please have look at IS-A and HAS-A.

class Animal{
}

class Dog extends Animal{
}

Here Dog extends Animal and Dog is an instance of Animal. This is IS-A relationship.

class Dog{
   private Collar collarObj;
}

Here Dog has an instance of Collar class. This is HAS-A relationship.