Java, A Beginner's Guide, 5th Edition, 5th Edition

Understanding Protected Members

Newcomers to Java are sometimes confused by the meaning and use of protected. As explained, the protected modifier creates a member that is accessible within its package and to subclasses in other packages. Thus, a protected member is available for all subclasses to use but is still protected from arbitrary access by code outside its package.

To better understand the effects of protected, let’s work through an example. First, change the Book class so that its instance variables are protected, as shown here:

Next, create a subclass of Book, called ExtBook, and a class called ProtectDemo that uses ExtBook. ExtBook ...