Page 883 - AP Computer Science A, 7th edition

27. (B) Classes that implement an interface must provide implementation code for all non-default (i.e., abstract) methods in the interface. Adding method2 to the SomeName interface means that all of those classes need to be rewritten with implementation code for method2. (This is not good—it violates the sacred principle of code reusability, and programmers relying on the interface will squeal.) Choices A, C, and D are all meaningless garbage. Choice E may be true if there is some other error in the new class. Otherwise, as long as the new class provides implementation code for both method1 and method2, the class will compile.