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SCJA Question About Ancestor and Sub Classes

Oscar Hansen
Greenhorn

Joined: Jul 09, 2008
Posts: 10
I am reading SCJA book by Cameron McKenzie and on page 166, I did not understand the answer to a question. Can someone explain me:

Sub classes:
- Should not be used as a method parameters when an ancestor class will suffice.

Thanks in advance!
Cameron Wallace McKenzie
author and cow tipper
Saloon Keeper

Joined: Aug 26, 2006
Posts: 4968
    
    1

The basic idea is that you always want to use the most general component whenever possible.

So, if I have a method, and all it does is print out the toString() method, I shouldn't force the argument to be a String, when I could just make the argument an Object. After all, every instance of an Object has a toString() method.

The more general, or abstract an argument is, the more flexible the method becomes. It makes your code more flexible and pluggable. That's the general idea.
 
Consider Paul's rocket mass heater.
 
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