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;
} // end foo constructor

public abstract int calculate();
} // end class foo

any concrete subclass that extends class foo:
1) must implement a method called calculate.
2) will not be able to access the instance variable a.
3) neither (a) nor (b).
4) both (a) and (b).

4) Both (a) and (b).

Explanation:

In addition to regular classes, Java has abstract classes. An abstract class is like a regular class. You can also define fields and methods in an abstract class, while at the same time, you cannot create an object or an instance of an abstract class. Abstract classes are designed to provide basic functionality for derived classes while derived classes required to implement this functionality.

A derived class must override and implement all abstract methods that are in the base abstract class. Therefore answer a (1) is correct.

Access modifier for the field a was private which means it has to be provided with accessor methods to obtain/modify its value. Therefor answer b (2) is correct as well.

no. when the asker posts the question they can make a question worth what ever they think is a fair price. although it must be within the limit of the points they currently own. 5 is the minimum number of points a question can be worth. if a question is complicated or has lots of parts to it, it is better to make it worth more because more people will be more willing to answer.

hope this !

hey! im not 100 percent sure but im pretty sure that what you want to do is not possible : (

explanation: