Hi guys,
I'm working on my java assignment but I don't know what did I do wrong. I successfully compile the file Book.java but got the error cannot find symbol while compiling BookTest.java . Thank you very much for any help.

Here's my Book.java

Code:
package question_1;
    public class Book {
    private String title; // Title of the book
    private String author; // Author of book :
    private
...