Question

Which of the following is NOT true about a class interface?

a) It consists of declarations of methods and variables.
b) The accessibility of these methods and variables can be set to public, protected, or private.
c) Instance variables are usually declared public.
d) It is the outside view of a class.

Answer 1

The incorrect statement about a class interface is that instance variables are usually declared public; in reality, they are typically private or protected to support encapsulation.

Step-by-step explanation:

The answer to the question: Which of the following is NOT true about a class interface? The incorrect statement about a class interface is option (c) Instance variables are usually declared public. In a class interface, instance variables are typically private or protected to promote encapsulation, thus making the 'outside view' of a class, usually comprised of public methods, the class interface.

The class interface includes a contract of what the class can do, without revealing how these operations are implemented, which corresponds to options (a) and (d). The interface declares methods and possibly constants. While accessibility of methods in an interface can be public, in full implementations accessibility may also include protected or private, especially for internal workings, referenced as option (b).