Question

JAVA LANGUAGE

15. In Java, single text characters are represented by what data type?

16. Which of the following statements about constructors are true? Circle all that apply.

a) A class can have many methods but only one constructor.

b) A constructor can be used instead of fields to represent the data inside a class.

c) A constructor wastes memory in the computer so it should be used sparingly.

d) A constructor is a special method that creates an object and initializes its state.

e) Constructors are considered bad programming style and should be avoided.

f) A constructor is the code that is called when you use the ‘new’ keyword.

17.   What is wrong with the following declaration?

class Table {

    Person student = new Person();

   

    public void getStudent() {

             return student;

    }

    // other methods go here…

}

18. Rewrite the following constructors, so the first one calls the second one:

public ClassOne(int alpha) {

    this.alpha = alpha;

    this.beta = 0;

}

public ClassOne(int alpha, int beta) {

    this.alpha = alpha;

    this.beta = beta;

}

19. Why is the code below showing a compile time error?

class X {

    private int m = 48;

}

class Y extends X {

    void methodOfY() {

        System.out.println(m);

    }

}

20.   What is printed by the following program?

public class Mystery {

    public static void main(String[] args) {

           String one = “two”;

           String two = “three”;

           String three = “1”;

           int number = 20;

           sentence(one, two, 3);

           sentence(“eight”, three, number / 2);

     }

      public static void sentence(String three, String one, int number){

            System.out.println(one + “ times “ + three + “ = “ + (number * 2);

      }

}

21. Suppose Car and Motorcycle are subclasses of Vehicle. Which of these declarations are allowed?

a) Car jaguar = new Vehicle();

b) Vehicle ferrari = new Car();

c) Motorcycle ducati = new Vehicle();

d) Motorcycle goldwing = new Car();   

Answer 1

15) In Java, single text characters are represented by what data type ?
---------->character

16)

d) A constructor is a special method that creates an object and initializes its state.

f) A constructor is the code that is called when you use the ‘new’ keyword.

17) Person student = new Person();
It cannot be initalised like this because this piece of code will never be called

18)

public ClassOne(int alpha) {

    this.alpha = alpha;
    this.beta = 0;
ClassOne(alpha, beta);

}

19) Why is the code below showing a compile time error?
Private fields cannot be inherited

20) Why is the code below showing a compile time error?
Private fields cannot be inherited

21)
three times two = 6
1 times eight = 20

22)b) Vehicle ferrari = new Car();

Thanks, PLEASE COMMENT if there is any concern.