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Thread: class hierarchy

  1. #1
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    Default class hierarchy

    Hello all...
    I am writing a class hierarchy for an assignment in my high school Java class and have a quick question on the structure...

    I need to make book, novel, magazine, technical journal and textbook classes / interfaces. Should book be an interface or an abstract class?
    I couldn't think of anything to put in the constructor so i made it an interface...do you see any problems with just an interface and they all implement it?

  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: class hierarchy

    It really depends. If you can justify it, then go with your justification. But it seems strange to me for every class to implement Book. By that logic, a magazine or a journal are books?

    I could also see things like passing an author, title, number of pages, etc into a Book constructor.

    But whether or not the constructor takes arguments does not determine whether a class is an abstract class or an interface (or a plain old class). An interface defines a common contract that any implementing classes agree to, an abstract class defines a subset of functionality that extending classes agree to complete.
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    Default Re: class hierarchy

    I think the abstraction should be highest from the root of the hierarchical tree, then decreased downward from the tree.

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