Question

In each of the following questions, first use NetBeans IDE to run the code (if there is an error fix it) then take a screenshot of the output and paste it under (A).

In (B), justify the output you obtained in (A).

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9. Given the following:

public class WorkingSheet {

    public static void main(String[] args) {

       B myB = new B();

       A myA = new B();

       System.out.print(myB instanceof A);

       System.out.print(myB instanceof C);

       System.out.print(myA instanceof B);    }

}

class B extends A implements C, D {

    int getID() {return 6;}}

class A {public int name;}

interface C {public final int a = 1;}

interface D {public final int b = 2;}

(A) What is the output of running the above program ?

(B) Justify your answer in (A)

10. Given the following,

public class Figures {

    public static void main(String[] args) {

        printFigure(8);

    }

    static void printFigure(int num) {

        if (num <= 2) {

            System.out.println(" A ");

        } else {

            System.out.println(" B ");

            printAnotherFigure(num - 2);

        }

    }

    static void printAnotherFigure(int n) {

        if (n <= 2) {

            System.out.println(" C ");

        } else {

            System.out.println(" D ");

            printFigure(n - 1);

        }

    }

}

(A) What is the output of running the above program?

(B) Justify your answer in (A)

Answer 1

The answer to this question is as follows:

The answer to the first question is as follows:

We are creating the object myB as the object for class B then class B is inheriting the class A and inheriting the class c and class D this is called as the multiple inheritances

when the statement myB is an instance of A is true because class B extends class A so the output is true

for the myB is an instance of c is true because class B extends the class c so the output is true

for the myA is an instance of B is also true because we are implementing with the polymorphism of class B so the output is true

so the output is true true true

The answer to the second question is :

B
D
B
D
A

First, we are calling printFigure(8) then 8<=2 false then else will be executed then the value B is printed

then we are calling the printAnotherFigure(num-2) i.e printAnotherFigure(6) then the value 6<=2 false then the value D is printed then

we are calling the printFigure(num-1) i.e printFigure(5) i.e 5<=2 false then B is printed

then we are calling printAnotherFigure(3) i.e 3<=2 false then D is printed then calling printFigure(2) is called then value 2<=2 is true it prints the value A