CODEWITHSUNDEEP
javainheritance
elias
elias

Reputation: 37

java how to extend a class while implement parent method

I have class A, and class B inherit class A, and class C inherit class B,

and all of the classes have this method:

public void someMethod();

How can i call this method from class C so the method from class A would be implemented?

Upvotes: 3

Views: 1120

Answers (3)

Michael S
Michael S

Reputation: 1865

As a matter of design, you can declare someMethod() final in class A, then all three have it, but cannot change the implementation. Then have a second method which does the second thing needed in B.

Or for a more complex situation, some refactoring idea like this may also help: http://www.refactoring.com/catalog/formTemplateMethod.html

Upvotes: 0

Bohemian
Bohemian

Reputation: 425013

You can't.

You can call the implementation from the parent:

super.someMethod();

But that's all. If B defines an implementation, that's the one that will get called. If not, A will get called, but you can't force A to be called (bypassing B).

The reason is that because C inherits from B, it's up to the implementation in B whether or not the implementation in A is used. There may be a very good reason why the implementation in A should not be used.

If you want C to use A's implementation, inherit directly from A. If you need some code from B, consider delegating to an instance of B.

Upvotes: 4

Amit Sharma
Amit Sharma

Reputation: 6154

Any class can only access instance of its immediate parent using super. You can not access grandparent.

Which means in C's member function you can invoke super.someMethod(). This will invoke, B's someMethod() implementation. However, any given object does not have access to instance of its grandparent.

Hence you can not invoke A.someMethod() implementation from C.

Upvotes: 2

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