Здравейте, 

На задача 4 от лекцията Iterators and Comparators от Java Advanced ми гърми един тест в Judge. Задачата е решена по същия начин и в презентацията и в лекцията, но не откривам проблема.

BookComparator class-a -> https://pastebin.com/PpPMDR7c

Book class-a -> https://pastebin.com/da20f2Vi

Main class-a -> https://pastebin.com/tzMgQgHF

Линк към задачата в Judge -> https://judge.softuni.org/Contests/Practice/Index/1542#3

Условието на задачата: 

Create a class BookComparator from UML diagram below:

BookComparator has to compare two books by:

1. Book title
2. Year of publishing a book

Examples

public static void main(String[] args) {

  Book bookOne = new Book("Animal Farm", 2003, "George Orwell");

  Book bookThree = new Book("The Documents in the Case", 2002);

  Book bookTwo = new Book("The Documents in the Case", 1930, "Dorothy Sayers", "Robert Eustace");

  

  List<Book> books = new ArrayList<>();

  books.add(bookOne);

  books.add(bookTwo);

  books.add(bookThree);

  

  books.sort(new BookComparator());

  

  for (Book : books) {

       System.out.println(book.getTitle() + book.getYear());

  }

}