Java’s interface language feature confuses many Java newbies. Many mistakenly assume that interfaces only sidestep Java’s failure to support multiple implementation inheritance.

The interface exists only to associate metadata with a class. For example, Cloneable (see Inheritance in Java, ... As with interface implementation, you can extend multiple interfaces.

It seems that MI has fallen severely out of favor. Neither of the two "big" programming languages to come out in the last few years, Java or C#, make use of multiple implementation inheritance ...