Member Access Modifiers

• Methods and instance (nonlocal) variables are known as "members."
• Members can use all four access levels: public, protected, default, private.
• Member access comes in two forms:
• Code in one class can access a member of another class.
• A subclass can inherit a member of its superclass.
• If a class cannot be accessed, its members cannot be accessed.
• Determine class visibility before determining member visibility.
• public members can be accessed by all other classes, even in other packages.
• If a superclass member is public, the subclass inherits it—regardless of package.
• Members accessed without the dot operator (.) must belong to the same class.
• this. always refers to the currently executing object.
• this.aMethod() is the same as just invoking aMethod().
• private members can be accessed only by code in the same class.
• private members are not visible to subclasses, so private members cannot be inherited.
• Default and protected members differ only when subclasses are involved:
• Default members can be accessed only by classes in the same package.
• protected members can be accessed by other classes in the same
• package, plus subclasses regardless of package.
• protected = package plus kids (kids meaning subclasses).
• For subclasses outside the package, the protected member can beaccessed only through inheritance; a subclass outside the package cannot  access a protected member by using a reference to a superclass instance (in other words, inheritance is the only mechanism for a subclass outside the package to access a protected member of its superclass).
• A protected member inherited by a subclass from another package is not accessible to any other class in the subclass package, except for the subclass' own subclasses.