Consider the abstract superclass below:
public abstract class Foo {
Private int a;
Public int b;
Public Foo(int aVal, int bVal) {
A = aVal;
B = bVal;
}
Public abstract int calculate();
}
Any concrete subclass that extends class Foo:
A) Must implement a method called calculate.
B) Will not be able to access the instance variable
C) Neither (a) nor (b).
D) Both (a) and (b).

Question

Consider the abstract superclass below: 
public abstract class Foo {
Private int a;
Public int b;
Public Foo(int aVal, int bVal) {
A = aVal;
B = bVal;
}
Public abstract int calculate();
}
Any concrete subclass that extends class Foo:
A) Must implement a method called calculate.
B) Will not be able to access the instance variable
C) Neither (a) nor (b).
D) Both (a) and (b).

Quizplus · Accepted Answer

A) The abstract superclass has an abstract method called calculate() which means that any concrete subclass extending this superclass must implement this method. Therefore, choice A is correct.

B) The private instance variable 'a' cannot be accessed directly by any subclass, but the public instance variable 'b' can be accessed. Therefore, choice B is incorrect.

Overall, both (a) and (b) are true, making choice D the correct answer.

Consider the Abstract Superclass Below