This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
There are no Mixin classes in Java. All you have is interfaces. Mixins are supported in other JVM based languages like Scala (they are called as Traits there), Groovy and JRuby as well. But search for mixins or mixins in java does return few useful results.