Java: Protection Type of Variables, Methods or Classes

There are four levels of protection for variables, methods and Classes in Java and are listed and described below:

Package Protection (DEFAULT)	Default, not an explicit form of protection. Variables,Methods or Classes of this type are accessibley only to all other classes in the same package. Even if another package is imported, its package protected variables, methods and classes are not accessible, they stay hidden.
Private	Means that your methods, variables are accessible only to other methods in the same class. NOT used for classes. Example: class Student_Record { private String Social_Security_Number; private float GPA; String Name; ..... } In the above example the GPA and SS# are private to this class, but, the Name is accessible by classes of the same package.
Public	Such methods, variables and classes are accessible to other methods inside or outside the current class or package. Declare by preceeding declaration with the word public.
Protected	Such methods and variables are accessible to all classes inside the same package but only to subclasses outside the package. NOT used for classes. Declare by preceeding declaration with the word protected. Support ability of subclasses to modify the data in a parent class even when this parent class is in a different package. Yet, do not have to declare public and let any class touch the data.

Handy-Dandy Cross-Reference Table

	Same Class	Sub Class	Same Package	Class outside package
public	X	X	X	X
protected	X	X	X	(only subclasses)
private	X
package protected (default)	X	X	X