Question

I am pretty new to Java, so I may be using incorrect terminology. I am trying to gracefully extend a class to a new class which holds multiple instances of the superclass. For example, say I have a class

class Rose{
   String smell;
   Rose(String smell){this.smell=smell;}
   void sniff(){ println("smells "+smell);}
}

And I want to define a class like…

class Bouquet extends Rose{
   ArrayList<Rose> roses;
   ...
}

holding multiple roses. My actual code has something like 20 methods, and for most of them the extended method would be

void sniff(){
   for( Rose one: roses) one.sniff();
}

Is there a way to construct bouquet in such a way that I don’t need to explicitly define these silly loops? I’m not tied to ArrayList, I could even make a new super class if that’s the way to go about it. However, it is important that I can send a bouquet instead of a rose argument to externally written methods.

EDIT:
Haha, I think my flower metaphor was a big fail. 🙂 But your input is good; you guys have clarified my thinking a bit.

In my real problem, there are a set of operations that define how to add instances of the base class together into a new instance of the base class. Perhaps a better metaphor would be twisting a number of small fabric strands together into one rope. External methods should treat a rope and a strand exactly the same.

It does seem like extends is wrong, any other suggestions?

Answer 1

You dont really need to extend bouquet from roses. You extend only when there is an IS A relationship, like you have Flower class and Rose is a Flower. But bouquet is not a rose. Ideally you should have a bouquet class which HAS many roses. If there is a 1:N relationship, then you will have to loop through to get individual items.