Consider the class Class Value { Private T v; Public Value(T v1){ V = v1; } Public void output(){ System.out.println(v); } } The code Value nV1 = new Value(34.5); A) will cause a compiler error B) will compile correctly,but cause an exception at run time C) will compile and run correctly D) None of the above

Question

Consider the class Class Value < T extends Number > { Private T v; Public Value(T v1){ V = v1; } Public void output(){ System.out.println(v); } } The code Value< Double > nV1 = new Value< Double >(34.5); A) will cause a compiler error B) will compile correctly,but cause an exception at run time C) will compile and run correctly D) None of the above

Quizplus · Accepted Answer

The class Value is defined with a generic type parameter T which extends Number. In this case, we create an instance of Value with Double as the type argument, and pass it the value 34.5. This is legal because Double is a subclass of Number, and 34.5 is a legal value for a Double. Therefore, the code will compile and run correctly, and the output method will print the value 34.5.

Consider the Class Class Value < T Extends Number >