Book-Store java application

a simple Java application that let the user make a Book Store, Add Books by:

1. Enter books information
2. Display books information
3. Search by book's title
4. Discount 15% from books prices

I created Book class which contains the private data members and includes display() method that prints information of any Book object. and then I wrote a java application which tests the previous class capabilities, and there are another 4 static methods beside “main” and “menu”, I have also added a proper validation & Exceptions in each class.