Which of the following are true statements?
a. A top-level class can not be called "tightly encapsulated" unless it is declared private.
b. Encapsulation enhances the maintainability of the code.
c. A tightly encapsulated class allows fast public access to member fields.
d. A tightly encapsulated class allows access to data only through accessor and mutator methods.
e. Encapsulation usually reduces the size of the code.
f. A tightly encapsulated class might have mutator methods that validate data before it is loaded into the internal data model.
What is mutator method? If it refers to manupulation of class data members, then it is not appropriate for data access. Therefore d should be not correct.....
"mutation" means "alteration"/change. So, mutator methods means, methods that allows modification of objects. In java layman terms it would be "setter" methods.
Also, you might be aware of the fact that "String" is an immutable object. We can't change string. Every operation results into "new" string object created.
Hope this helps.
Methods that appear to be mutator methods but in fact return a new instance of an immutable class are what I call the Would-Be Mutator design pattern, which is a proven programming technic for the design of immutable classes. IT SHOULD NOT BE CONFUSED WITH MAKING DEFENSIVE COPIES, however. No less than Joshua Bloch does this in Effective Java. Making defensive copies is a programming technic that is absolutely necessary in order to encapsulate references to mutable objects. These are two very different motivations.