How can I write a method and force the subclasses to override this method. In Eclipse it should show in the Quick-Fix Dialog: "Add unimplemented methods".
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How can I write a method and force the subclasses to override this method.
Declare the method as abstract:
Eclipse will give you the "Add unimplemented methods"-option for all (unimplemented) abstract methods and interface methods.
aioobe
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Not a general answer. A class with an abstract method can't be instantiated. (only it's sub-classes can) – Mark Jeronimus Dec 24 '22 at 18:10
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An abstract class is instantiated when its subclass is instantiated. – aioobe Dec 24 '22 at 18:53
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I meant that I have instances of both the base class and subclasses, and both need an actual implementation of a method, but subclasses must be enforced to override the base class implementation. – Mark Jeronimus Dec 25 '22 at 10:51
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@MarkJeronimus, do you mean that you _have_ an implementation in the base class, but still want to require subclasses to implement (override) the method? – aioobe Dec 25 '22 at 11:37
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Yes. Although I eventually settled on making a separate base class that isn't polymorphically connected – Mark Jeronimus Dec 26 '22 at 18:56
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Just declare the method as abstract in the base class. All children classes will then be forced to implement it. Alternatively you could also use an interface instead of a concrete class, which is simply an agreement that the methods defined will be implemented. Either one is fine, it depends on your needs.
Chris Eberle
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You can do that by making the method abstract (not providing a default implementation).
rsp
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Or if you do NOT want your class to be an abstract class, you can throw your own MustOverrideException at the method that you want to force to be overridden.
Lemuel Adane
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