Understanding Protected Members

• The protected modifier allows a member to be accessed within its package and by subclasses in other packages.

• A protected member can be used by all subclasses, but remains protected from access by code outside the package.

• An example can help you better understand the effect of protected.

• In the example, the Book class is changed so that its instance variables are protected.

• Create a subclass of Book called ExtBook.

• Create a class called ProtectDemo that uses ExtBook.

• ExtBook adds a field to store the publisher name.

• ExtBook also has several accessor methods.

• The two classes (ExtBook and ProtectDemo) are in the bookpackext package.

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• ExtBook extends Book, which allows you to access protected Book members, even though they are in different packages.

• ExtBook can directly access protected members such as title, author, and pubDate, creating accessor methods for these variables.

• In the ProtectDemo class, direct access to these variables is denied because ProtectDemo is not a subclass of Book.

• If the comment is removed from the books[0].title = "test title"; line, the program will not compile due to access restriction.

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