of an abstract class and
your class will only be non-abstract if <em>all</em> of the abstract functions
have been overloaded correctly. Therefore the compiler can confirm that all
the methods required by the interface have been provided. If you have missed
out a method or mis-defined it, there will still be at least one abstract
method inherited from the interface class and therefore your class will be
abstract too. A compiler error will be produced when you try to create an
object of the class.</p>

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