The public Book class : Access Control « Class Definition « Java Tutorial

package yourpackagename;

public class Book {
    String isbn;
    String title;
    int width;
    int height;
    int numberOfPages;

The Book class is a member of the yourpackagename package and has five fields. Since Book is public, it can be instantiated from any other classes.

  1. A public class must be saved in a file that has the same name as the class, and the extension must be java.
  2. A Java source file can only contain one public class.
  3. A Java source file can contain other classes that are not public.

5.25.Access Control
5.25.1.Access Control: four access control modifiers
5.25.2.Class Access Control Modifiers
5.25.3.Using Access Attributes
5.25.4.Class Member Access Matrix
5.25.5.Specifying Access Attributes
5.25.6.The public Book class
5.25.7.Default access level
5.25.8.Class Member Access Control Modifiers
5.25.9.Composition with public objects
5.25.10.The protected keyword
5.25.11.Private Override
5.25.12.Understand the effects of public and private access
5.25.13.In a class hierarchy, private members remain private to their class.
5.25.14.A Superclass Variable Can Reference a Subclass Object
5.25.15.Create a Singleton Object