public class Book {

    private String title;
    private String author;
    private int copyrightYear;
    private int available;
    private  Size size;

    public Book(String title, String author, int year, Size sz) {
        this.title = title;
        this.author = author;
        this.copyrightYear = year;
        this.available = 2; //two copies of the same book
        this.size = sz;
    }

    public String getTitle() {
        return title;
    }

    public String getAuthor() {
        return author;
    }

    public int getYear() {
        return copyrightYear;
    }

    public Size getSize() {
        return size;
    }

    public boolean equals(Book book) {
        if (book.getTitle().equals(this.getTitle()) &&
            book.getAuthor().equals(this.getAuthor()) &&
            book.getYear() == this.getYear() &&
            book.getSize().equals(this.getSize())) {
            return true;
        } else {
            return false;
        }
    }

    public boolean getAvailable() {
        if (available > 0) {
	    return true;
	}
        else {
	    return false;
        }
    }

    public void checkOut() {
        if (available > 0) {
            available--;
        } else {
            System.out.println("Error: Tried to check out an unavailable book.");
        }
    }

    public void checkIn() {
        if (available > 1) {
            System.out.println("Error: Tried to check in an available book.");
        } else {
            available++;
        }
    }

    public static void main(String[] args) {
        Size sz1 = new Size(); //default constructor height=11, width=8.5 
        Size sz2 = new Size(11, 8.5);

        Book testBook1 = new Book("T1", "A", 2001, sz1);
        Book testBook2 = new Book("T1", "A", 2001, sz2);

        if (testBook1.equals(testBook2)) {
            System.out.println("Equal books");
        } else {
            System.out.println("Unequal books");
        }

        testBook1.checkOut();
        if (testBook1.getAvailable()) {
            System.out.println("One copy of the book Available");
        } else {
            System.out.println("Book not available any more");
        }
   
        testBook1.checkOut();
        if (testBook1.getAvailable()) {
            System.out.println("Error: All copies of the book were checked out but still available");
        } else {
            System.out.println("Correct: no copy of the book is available any more");
        }
    }
}