289: Highlights

• Inadvertent instance-variable accesses and assignments destroy data abstraction.
• You can prevent inadvertent direct access to instance variables by making such instance variables private. Thus, the public–private dichotomy helps to ensure that you can benefit from data abstraction.
• The public instance variables and public instance methods constitute the class's public interface.
• If you want to provide universal access to instance variables and methods, then mark them with the public keyword.
• If you want to limit access to instance variables and methods to the class in which they are introduced and to subclasses of the class in which they are introduced, then mark them with the protected keyword.
• If you want to limit access to instance variables and methods to the class in which they are introduced, then mark them with the private keyword.