21. Consider the following class definitions. public class Data { private int x;

Question

21. Consider the following class definitions.

public class Data
{
     private int x;
     public void setX(int n)
     {
          x = n;
     }
     //... other methods not shown
}

public class EnhancedData extends Data
{
    private int y;
    public void setY(int n)
    {
        y = n;
    }
    //... other methods not shown
}

Assume that the following declaration appears in a client program.

EnhancedData item = new EnhancedData();

Which of the following statements would be valid?

I. item.y = 16;

II. item.setY(16);

III.item.setX(25);

Question 21 options:

II only

I only

II and III only

I, II and III

I and II only

22. Consider the following class definitions.

public class A
{
     private int a1;

     public void methodA()
     {
            methodB();   //Statement 1
     }
}

public class B extends A
{
     public void methodB()
     {
            methodA();   //Statement II
            a1 = 0;          //Statement III
      }
}

Which of the labeled statements in the methods shown above will cause a compile-time error?

Question 22 options:

I only

III only

I and III

II and III

I and II

23. Assume that a, b, and c are variables of type int. Consider the following three conditions.

I. (a == b) && (a == c) && (b == c)
II. (a == b) || (a == c) || (b == c)
III. ((a - b) *(a - c) * (b - c) == 0

Assume that subraction and multiplication never overflow. Which of the conditions above is (are) always tuure if at least two of a, b, and c are equal?

Question 23 options:

I only

I and II

III only

II only

II and III

24. Consider the following two static methods, where f2 is intended to be the iterative version of f1.

public static int f1(int n)
{
     if (n < 0)
     {
           return 0;
     }
    else
     {
           return (f1 (n -1) + n * 10);
     }
}

public static int f2(int n)
{
      int answer = 0;

      while (n > 0)
       {
            answer = answer + n * 10;
            n--;
       }

       return answer;
}

The method f2 will always produce the same results as f1 under which of the following conditions?

I. n < 0
II. n = 0
III. n > 0

Question 24 options:

II and III only

I, II and III

II only

III only

I only

25. Consider the following code segment.

int k = 1;

while (k < 20)
{
     if ((k % 3) == 1)
          System.out.println (k + " ");

    k++;
}

What is printed as a result of executing this code segment?

Question 25 options:

2 4 6 8 10 12 14 16 18 20

1 3 5 7 9 11 13 15 17 19

3 6 9 12 15 18

1 4 7 10 13 16 19

2 5 8 11 14 17

II only

I only

II and III only

I, II and III

I and II only

Explanation / Answer

Q21. Ans: II and III only

Q22. Ans: III only, a1 is not visible in class B

Q23. Ans:  II and III

Q24. Ans:  I, II and III

Q25. Ans: 1 4 7 10 13 16 19

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