SUMMER 23

Q1

Initializing Vehicle class...
Making sure of initialization...
Initializing an instance of the Vehicle class...
Creating a default vehicle.
The vehicle emits a honking sound.
model=null brand=Unknown
Initializing an instance of the Vehicle class...
Creating a customized vehicle of brand: Ford and model: F- 150
The vehicle emits a custom honking sound: Loud horn sound
model=F- 150 brand=Ford

Q2

Electronic Device.java

public class ElectronicDevice {


    String brand;
    double price;

    public ElectronicDevice(String brand, double price){
        this.brand = brand;
        this.price = price;
    }

    public void displayInfo(){
        System.out.println("Brand: "+ brand);
        System.out.println("Price: $"+price);
    }
}

Smarphone.java

public class Smartphone extends ElectronicDevice{
private    String model;
private String operatingSystem;
private    String IMEI;

Smartphone(String brand, double price, String model, String operatingSystem){
    super(brand, price);
    this.model = model;
    this.operatingSystem = operatingSystem;
}

public void displayInfo(){
    System.out.println("Brand: "+super.brand);
    System.out.println("Price: "+super.price);
    System.out.println("Model: "+ model);
    System.out.println("Operating System: "+ operatingSystem);
}

public  String getIMEI(){
    return IMEI;
}

}

Q3

Main.java

public class Main {
    public static void main(String[] args) {
        MyObject[] myObjects = {
                new Sphere(2.5),
                new Cone(1.9,8.9),
                new Cylinder(1.5,6.5),
                new Cone(2.7,5.7),
                new Sphere(3.5)
        };


        double volume = 0;
        for (MyObject obj: myObjects){
            volume+= obj.findVolume();
        }

        System.out.println("Sum of Volume is : "+ volume);

    }

MyObject.java

public class MyObject {
    private double r;

    MyObject(double r){
        this.r = r;
    }
    public double findVolume(){
        return -1.0;
    }

    public double getRadius(){
        return r;
    }
}

Sphere.java

public class Sphere extends MyObject {

Sphere(double r){
super(r);
}
public double findVolume(){
    double r = super.getRadius();
    return (4.0/3.0)*Math.PI*Math.pow(r,3);
}
}

Cylinder.java

public class Cylinder extends  MyObject{
    private double h;

    Cylinder(double r, double h){
        super(r);
        this.h = h;
    }
    @Override
    public double findVolume() {
        double r  = super.getRadius();
        return Math.PI*Math.pow(r,2) * h;
    }

    public double getHeight(){
        return h;
    }
}

Cone.java

public class Cone extends Cylinder{

    Cone(double r, double h){
        super(r, h);
    }

    public double findVolume(){
        double r = super.getRadius();
        double h = super.getHeight();

        return 1/3.0 * Math.PI*r*r *h;
    }
}

Q4

FinalContext.java

public class FinalContext {
    public final void calculate(){
        System.out.println("calculate method is called");
    }
}

StaticContext

public class StaticContext extends FinalContext {
    final static int value;
    static {
        value = 8;
    }

   private double mark = 90;
    private static int count;

    private static int getCount(){
        return ++count;
    }

    private double getMark(){
        return mark;
    }


    public static void main(String[] args) {
        count++;

        System.out.println("count = "+getCount());
        System.out.println("value = "+ value);
        FinalContext sv = new StaticContext();
        System.out.println("mark  ="+((StaticContext)sv).getMark());
        sv.calculate();

    }

}

Q5 A

i

No, a class cannot be both abstract and final simultaneously. This is because:

An abstract class is meant to be inherited from and extended by other classes. It's designed to be incomplete and requires subclasses to implement its abstract methods.

A final class, on the other hand, cannot be inherited or extended. It's designed to be complete in itself and prevent further modification through inheritance.

ii

Yes, there are reasons to create an abstract class without instance variables or methods:

To define a common type for a group of related classes. It can serve as a base type for a family of classes, even if it doesn't provide any shared implementation.

To provide default implementations for certain methods that can be overridden by subclasses

iii

A class with an abstract method needs to be declared abstract because it cannot be instantiated. This is because an abstract class is not meant to be used directly; it is meant to be subclassed and extended by other classes

Q5 B

Animal.java

public abstract class Animal {
}

class Baby extends Animal{
    public double age;

}

class Cat extends Animal{
    public void sleep(int time){
        System.out.println("Sleeping");
    }
}

Main.java

public class Main {

    public void speak(Animal target){
        if (target instanceof  Baby){
            System.out.println("WAAHHH");
        }
        else if (target instanceof Cat){
            System.out.println("Meow");
        }
        else{
            System.out.println("Grrrr");
        }
    }


}