java traits or mixins pattern?

Question

Is there a way to emulate mixins or traits in java? basically, I need a way to do multiple inheritance so I can add common business logic to several classes

Answer 1

Java's answer to multiple inheritance is the ability to implement multiple interfaces. Of course, this means you'll get the method declarations, but not the logic.

You could try emulating mixins by composition: your Java class could define member variables that represent other classes that perform some common business logic.

In designing Java classes, I have not found the lack of C++ style multiple inheritance to inhibit the design of my architecture. You will find a way to achieve what you want to do.

Answer 2

Implementing simple mixin/traits support in java using CGLib/javassit is quite easy. You can take a look for instance here for small example. More complete, ready to use solution might be found: here