Question

1. Java Abstract Class (2 pts) () • A Java abstract class is a class that can't be instantiated. That means you cannot create new instances of an abstract class. It works as a base for subclasses. You should learn about Java Inheritance before attempting this challenge.

• Following is an example of abstract class:

abstract class Book{

String title;

abstract void setTitle(String s);

String getTitle(){

return title;

}

}

If you try to create an instance of this class like the following line you will get an error:

Book new_novel=new Book();

• You have to create another class that extends the abstract class. Then you can create an instance of the new class. Notice that setTitle method is abstract too and has no body. That means you must implement the body of that method in the child class. In the editor, we have provided the abstract Book class and a Main class. In the Main class, we created an instance of a class called MyBook. Your task is to write just the MyBook class. Your class mustn't be public

. • Sample Input A tale of two cities

• Sample Output The title is: A tale of two cities

+ import java.util.*; abstract class Book{

String title;

abstract void setTitle(String s);

String getTitle(){

return title;

}

}

//Write MyBook class here public class Main{

public static void main(String []args){

//Book new_novel=new Book(); This line prHMain.java:25: error: Book is abstract; cannot be instantiated Scanner sc=new Scanner(System.in);

String title=sc.nextLine();

MyBook new_novel=new MyBook();

new_novel.setTitle(title);

System.out.println("The title is: "+new_novel.getTitle());

sc.close();

}

}

Answer 1

// Main.java : Java class to implement Book inheritance

import java.util.*;

// abstract class Book
abstract class Book{

   String title;
   abstract void setTitle(String s); // abstract method
  
   String getTitle(){
       return title;
   }
}

// concrete class that extends Book class
class MyBook extends Book {

   // override the setTitle method of Book class
   @Override
   void setTitle(String s) {
       title = s;
   }
  
}

public class Main {

   public static void main(String[] args) {

       //Book new_novel=new Book(); This line prHMain.java:25: error: Book is abstract; cannot be instantiated
       Scanner sc=new Scanner(System.in);
       String title=sc.nextLine();
       MyBook new_novel=new MyBook();
       new_novel.setTitle(title);
       System.out.println("The title is: "+new_novel.getTitle());
       sc.close();

   }

}

//end of Main.java

Code Screenshot:

Output: