This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
1. Enum cannot extend a class but can implement an interface. true
2. we cannot extend or implement enum. true. Because enums are basically classes and when the byte code is generated, they are final. They are not interfaces, so they cannot be implemented.
3. Enums are implicitly final. true.
An interesting note on side: enums declared within class (enums that are not top level classes) are static by default whether use the keyword or not. But enums that are top level classes in their own files are not static, in fact, if you use the static keyword, a compile time error is raised.