Book.java

public non-sealed class Book implements MediaItem, Borrowable{

    private String title;
    private String author;
    private String isbn;
    private boolean available = true;
    private String borrowedBy;

    public Book(String title, String author, String isbn){
        this.title= title;
        this.author=author;
        this.isbn = isbn;
    }

    public String getTitle(){
        return title;
    }

    public void borrow(String user){
        if (available){
            available = false;
            borrowedBy = user;
            System.out.println(user + " borrowed " + title);
        } else{
            System.out.println("Item is not available, already borrowed by " + borrowedBy);
        }
    }

    public void returnItem(){
        if(!available){
            available = true;
            System.out.println(title + " returned by " + borrowedBy);
            borrowedBy = null;
        }
    }
    public boolean isAvailable(){
        return available;
    }


    @Override
    public String toString() {
        return "Book: " + title + " | Author: " + author;
    }
}