You can declare that an interface is a functional interface by preceding it with the @FunctionalInterface annotation.The compiler will then ensure that the interface contains ________;otherwise,it'll generate a compilation error.
A)no abstract methods
B)all abstract methods
C)only one abstract method
D)one or more abstract methods.

Question

Quizplus · Accepted Answer

By using @FunctionalInterface annotation, the interface is explicitly stating that it is a functional interface, therefore containing only one abstract method, and if any extra abstract method is present it will generate a compilation error.

You Can Declare That an Interface Is a Functional Interface