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Message:
need some notes
Posted by aziz on January 12, 2002 at 7:37 AM
> What is the differences between the inheriance methods used by java and C++ > > > > Is their anyway (through either inheritance or interfaces) > > > to declare an abstract static method? I would like > > > to use polymorphism for several classes and I would > > > like all of them to have static method.
> > > I know I could do this by having the static method (not > > > abstract) in the super class and then overriding the > > > method in the subclasses, but I would like to have the > > > method abstract so it would be required to rewrite the > > > method to create the subclass. > > I'm afraid you can't always get what you want. Java has no > > abstract static methods. Abstract methods are bound up in > > the polymorphism thing. They are intended to provide > > templates for subclasses not to simply "rewrite" but to > > "override" -- so that when they are invoked from a superclass > > reference type, dynamic binding causes the appropriate > > subclass implementation of the method to run. Static methods > > are bound at compile time based on the type of the reference, > > not at run time based on the class of the object. When you > > rewrite a static method in a subclass, you aren't "overridding" > > the superclass version of the method, but simply "hiding" it. > > But if you invoke the method on a superclass type reference to > > the subclass object, you'll still just get the superclass > > implementation of the method. Even though your holding a > > reference to a subclass object, the static method > > implementation to invoke is decided at compile time based on > > the type of the reference, which is the superclass. > > bv > > invoke
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