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Thread: Abstract Classes?

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    Default Abstract Classes?

    Could anyone explain to me the use of an abstract class and why I would prefer them over an interface?

    As far as I understand, both contain empty method declarations, except that you can implement the interface while you can't implement an abstract class, so what's the use?


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    Default Re: Abstract Classes?

    1Interface is the concept of encapsulation
    – The implementation can change without affecting the caller of the interface
    – The caller does not need the implementation at the compile time
    ● It needs only the interface at the compile time
    ● During runtime, actual object instance is associated with the interface type
    2. Example:
    – Class Line and class MyInteger
    ● They are not related through inheritance
    ● You want both to implement comparison methods
    – checkIsGreater(Object x, Object y)
    – checkIsLess(Object x, Object y)
    – checkIsEqual(Object x, Object y)
    – Define Comparison interface which has the three abstract methods above
    3. A class can implement multiple interfaces while it can extend only one class

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