Revisit Access Specifiers

Access specifiers, also known as access modifiers, are keywords in Java that set the accessibility (visibility) of classes, interfaces, variables, methods, and other members. They define the scope and visibility of these components.

There are four types of access specifiers in Java:

Public: The public keyword is an access modifier that makes a member (class, interface, variable, method, etc.) accessible from anywhere. This means that a public member is visible to all classes in all packages.
Private: The private keyword makes a member accessible only within the class in which it is declared. It is the most restrictive access level. So, variables, methods, and constructors that are declared private can't be accessed outside the class and are not visible to any other class, including subclasses.
Protected: The protected keyword makes a member accessible within the same package and also to subclasses of the class in any package. So, if you have a variable, method, or constructor declared as protected, it can be accessed within the same class, by other classes in the same package, and by subclasses in other packages.
Default (Package-Private): When no access specifier is specified, the member is treated as having "default" access, also known as "package-private". This means the member is accessible within the same class, and also by other classes in the same package, but not by classes in other packages or subclasses in other packages.

Access Modifier	Within Class	Within Package	Outside Package by subclass	Outside Package

Access Modifier	Within Class	Within Package	Outside Package by subclass	Outside Package
Private	Yes	No	No	No
Default	Yes	Yes	No	No
Protected	Yes	Yes	Yes	No
Public	Yes	Yes	Yes	Yes

By controlling access, you can prevent misuse. For example, with the private modifier, you can hide data from users of your class and allow access only through methods that you control. This concept is also known as data encapsulation or data hiding.