What modifiers are allowed for methods in an interface?

• A. Public and protected
• B. Protected and private
• C. Public and abstract
• D. Public only

Answer: (C)

In Java, methods declared in an interface inherently have certain characteristics. The main point to understand is that all methods in an interface are implicitly public and abstract. This means that explicitly declaring a method in an interface as public is redundant, as all interface methods are public by default. Likewise, the abstract modifier is not required either since interface methods cannot have a body, reinforcing the abstract nature.

By focusing on the characteristics of interface methods, the combination of public and abstract makes sense. Public indicates that the method can be accessed from any class implementing the interface, while abstract signifies that the implementing class must provide a concrete implementation for these methods.

Modifiers such as protected or private are not allowed for interface methods because it would contradict the intended purpose of an interface, which is to define a contract for any implementing class. Interfaces are supposed to facilitate a broad accessibility to these methods from any class that implements them. Hence, the combination of public and abstract perfectly captures the essence of method declarations in interfaces.