I have heard there is a way to cheat single inheritance and implement multiple inheritance in Java. Does anyone know how to implement this(with out using interface)?
Just out of curiosity 😉
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I have heard there is a way to cheat single inheritance and implement multiple inheritance in Java. Does anyone know how to implement this(with out using interface)?
Just out of curiosity 😉
Sure you can, but it’s tricky and you should really consider if that’s the way you want to go.
The idea is to use scope-based inheritance coupled with type-based one. Which is type-talk for saying that for internal purposes, inner classes ‘inherit’ methods and fields of the outer class. It’s a bit like mixins, where the outer class is mixed-in to the inner class, but not as safe, as you can change the state of the outer class as well as use its methods.
Gilad Bracha (one of the main java language designers) wrote a paper discussing that. So, suppose you want to share some methods for internal use between some unrelated classes (e.g, for string manipulation), you can create sub classes of them as inner classes of a class that has all the needed methods, and the sub classes could use methods both from their super classes and from the outer class.
Anyway, it’s tricky for complex classes, and you could get most of the functionality using static imports (from java 5 on). Great question for job interviews and pub quizzes, though 😉