This is java problem. I have writen the codes i am not sure what i do wrong, please fix it or add to make it works. I am not sure what did i do wrong and why it wont compile this is the direction:

-The Book class models information common to all books.

what do i need to do next this is my code, but i am not sure i did it correctly or not.

Class Book The Book class models information common to all books. Any book has: Fields: an author .an ISBN or International Standard Book Number that provides a unique number used by publishers and book stores Constructors and methods: a null constructor a constructor using 3 parameters for an author, title, and ISBN number getters and setters toString should provide a string of the field data in a format suitable for printing Within a Book class and its subclasses, these fields might be used directly, but processing by other classes and objects should bedone via getters and setters-encapsulation