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Asked: 2026-05-16T13:55:34+00:00

I have a lot of classes which are basically equivalent, ie have almost the

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I have a lot of classes which are basically equivalent, ie have almost the same functions in all respect. Let’s call them A and B. There are hundreds of methods that are using A and now due to code changes I have to change them to B.

Is there a way by which I can program a mapping between A and B such that I have minimal code changes?

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  1. Editorial Team

    If A is not final, you can make B extends A, and have B‘s methods @Override A‘s. Then wherever previously you were invoking methods on an instanceof A, you now provide an instanceof B, and let dynamic dispatch handle the rest.

    This is called polymorphism. It only works with non-static methods having the same exact signature. You can not @Override static methods.

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    On interfaces

    Depending on why you were doing this, you should know learn the concept of interfaces and how they’re used in object-oriented programming to allow precisely this kinds of flexibility and convenience.

    Consider the interface List<E>, for example, and an implementation ArrayList<E>. If you wrote an entire library that works with an ArrayList<E>, doing all the usual add/addAll/remove etc, and now you must use a LinkedList<E> instead, then you’d have little choice but to go to the source code and change all the ArrayList<E> to LinkedList<E>, and hope that the change doesn’t break another code which still assumed that ArrayList<E> was used.

    If instead your library works with a List<E>, then switching to a LinkedList<E> need to be done only wherever the objects are created. All the other code that was doing the add/addAll/remove would’ve still worked just fine, since those are methods that are defined in the interface List<E> which all implementors will have.

    It’s not clear from the current context, but if A and B are so similar, then perhaps they belong to some type X. If so, you should consider defining interface X, and have A implements X, and B implements X.

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