java 11-10-2023

i) Fill in the blank space to make this code an example of Polymorphism

ii) predict whether it prints the base class or derived class

class BuggyBread1 {
public String method() {
return "Base Class - BuggyBread1";
}
}

class BuggyBread2 extends BuggyBread1{

private static int counter = 0;

public String _______(int x) {
return "Derived Class - BuggyBread2";
}
public static void main(String[] args) {
BuggyBread1 bg = new BuggyBread2();
System.out.println(bg.method());
}
}

• i) method

  ii) prints the base class

• i)Buggybread2

  ii)prints the base class

• i) method

  ii)prints the derived class

• i)Buggybread2

  ii)prints the derived class

Fill in the blanks to print the output "Kapil". Separate the answers with ','.

class Person {

      private String name;  

    public String getName() { return name; }

    public void setName(String newName)

    {

        this.name = newName;

    }

}

  

class Main {

    public static void main(String[] args)

    {

        Person person = new Person();

                person._______("kapil");

        System.out.println(person.______());

    }

}

Predict the output of the following code.

import java.util.Random;  

class DeliveryBoy {  

    public void deliver() {

        System.out.println("Delivering Item");

    }  

    public static void main(String[] args) {

        DeliveryBoy deliveryBoy = getDeliveryBoy();

        deliveryBoy.deliver();

    }  

    private static DeliveryBoy getDeliveryBoy() {

        Random random = new Random();

        int number = random.nextInt(5);

        return number % 2 == 0 ? new Postman() : new FoodDeliveryBoy();

    }

}  

class Postman extends DeliveryBoy {

    @Override

    public void deliver() {

        System.out.println("Delivering Letters");

    }

}  

class FoodDeliveryBoy extends DeliveryBoy {

    @Override

    public void deliver() {

        System.out.println("Delivering Food");

    }

}

What do we mean by the "state" of an object?

• Its behavior

• Its methods

• Its interface

• The values assigned to its instance variables

public class Vehicle {
private static String manufacturingDate = "2016";
}
public class Car extends Vehicle{
public static void main(String args[]){
System.out.println(manufacturingDate);
}
}

• 2016

• No Output

• error - The field Vehicle.manufacturingDate is not visible

public class Vehicle {
private static String manufacturingDate = "2016";
static public class Car extends Vehicle{
public static void main(String args[]){
System.out.println(manufacturingDate);
}
}
}

• 2016

• No Output

• error - The field Vehicle.manufacturingDate is not visible

Static Polymorphic in Java is achieved through ..

• Method Overloading

• Method Overriding

• Variable Overloading

• Variable Overriding

package inheritancePractice;

public class P {

int a = 30; }

public class Q extends P {

. int a = 50; }

public class Test extends Q {

public static void main(String[] args) {

Q q = new Q();

System.out.println(" Value of a: " +q.a);

P p = new Q();

System.out.println("Value of a: " +p.a); } }

• Value of a: 30 Value of a: 50

  
  

• Value of a: 50 Value of a: 50

  
  

• Value of a: 50 Value of a: 30

  
  

• Value of a: 30 Value of a: 30

  
  

package finalPrograms;

public class FVar {

final int x;

final static int a;

FVar() { x = 30; }

void displayValue() {

System.out.println("Value of x: " +x); }

static {

a = 20;

System.out.println("Value of a: " +a); }

public static void main(String[] args) {

FVar fv = new FVar();

fv.displayValue(); } }

• Value of a: 30 Value of x: 30

• Output: Value of a: 20 Value of x: 20

• The final local variable x cannot be Changed.

• Output: Value of a: 20 Value of x: 30

class Base {

public Base() {

System.out.println("Base"); }

}

class Derived extends Base {

public Derived()

{ System.out.println("Derived"); }

}

class DeriDerived extends Derived {

public DeriDerived()

{ System.out.println("DeriDerived"); } }

public class Test {

public static void main(String[] args)

{ Derived b = new DeriDerived(); } }

• Derived

  DeriDerived

• Base

  Derived

  DeriDerived

• DeriDerived

  Derived

  Base

• DeriDerived

  Derived