abstract class Publication {
String title;
String author;
abstract void displayDetails();
}
class Book extends Publication {
String isbn;
public Book(String title, String author, String isbn) {
this.title = title;
this.author = author;
this.isbn = isbn;
}
@Override
void displayDetails() {
System.out.println("Book: Title: " + title + ", Author: " + author + ", ISBN: " + isbn);
}
}
class Textbook extends Book {
String subject;
public Textbook(String title, String author, String isbn, String subject) {
super(title, author, isbn);
this.subject = subject;
}
@Override
void displayDetails() {
System.out.println("Textbook: Title: " + title + ", Author: " + author + ", ISBN: " + isbn + ", Subject: " + subject);
}
}