Chapter 17, Problem 1MC

Program Description Answer

When instantiating a generic class, only reference type arguments are passed to the type parameters.

Hence, the correct answer is option “B”.

Explanation of Solution

Reference types only:

• Only non-primitive types can be substituted for type parameters when creating instances for generic class.
• Reference types are non-primitive types.
• The compiler autoboxes the primitive type values to reference types.

Explanation for incorrect options:

a. Primitive types only:

When creating instances for a generic class, only non-primitive types can be substituted for type parameters.

Hence, the option “A” is wrong.

c. Interface types only:

The type parameters can be specified as interface type but the arguments passed to type parameters at the time of instantiation, must be real types such as Integer, String, and so on.

Hence, the option “C” is wrong.

d. Primitive, reference, and interface types:

When creating instances for a generic class, only reference types can be substituted for type parameters.

Hence, the option “D” is wrong.