I do assignment for java which is write a program for book with the main class it's work but with 4 errors in cmd in print method

public String getAuthor()

{

return author;

}

public String getTitle()

{

return title;

}

public int getNumberOfPages()

{

return numberOfPages;

}

public int getIsbn()

{

return isbn;

}

public void displayBook()

{

System.out.println("Book Author:"+Author);

System.out.println("Book NumberOfPages:"+NumberOfPages);

System.out.println("Book Title:"+Title);

System.out.println("Book Isbn:"+Isbn);

}

}

and this is the main class

public class TestBook

{

public static void main(String args[])

{

Book book1=new Book();

Book book2=new Book();

Book book3=new Book();

book1.setAuthor("Dr. Franc Morino");

book1.setNumberOfPages(202);

book1.setTitle("My Story");

book1.setIsbn(1122554);

book2.setAuthor(" Lady Gaga");

book2.setNumberOfPages(10);

book2.setTitle("Cool by The Pool");

book2.setIsbn(1122554);

book3.setAuthor(" D.J. Khaled");

book3.setNumberOfPages(10);

book3.setTitle("Hot By The Spot");

book3.setIsbn(1122554);

System.out.println("--------------------------------");

book1.displayBook();

System.out.println("--------------------------------");

book2.displayBook();

System.out.println("--------------------------------");

book3.displayBook();

System.out.println("--------------------------------");

}

}