This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Well, an empty interface has a special name (a "marker interface"), and the JDK contains a number of examples of how they used to be used, back before annotations were introduced in Java5. An empty abstract class -- well, that's just dumb