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

Multiple interface inheritance still allows an object to inherit methods and to behave polymorphically on those methods. ... Core Java Java Programming Languages how-to ...

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 ...