what is ‘public’, ‘private’ and 'protected' in java code example

Example: access specifiers in Java

In Java, access specifiers are the keywords which are used to define 
the access scope of the method, class, or a variable. 
  In Java, there are four access specifiers.
  
  * Public: The classes, methods, or variables which are defined as public, 
  can be accessed by any class or method.
  * Protected: Protected can be accessed by the class of the same package, 
or by the sub-class of this class, or within the same class.
  * Default: Default are accessible within the package only. 
    By default, all the classes, methods, and variables are of default scope.
  * Private: The private class, methods, or variables defined as private 
    can be accessed within the class only