Java, A Beginner's Guide, 5th Edition, 5th Edition

Packages

In programming, it is often helpful to group related pieces of a program together. In Java, this is accomplished by using a package. A package serves two purposes. First, it provides a mechanism by which related pieces of a program can be organized as a unit. Classes defined within a package must be accessed through their package name. Thus, a package provides a way to name a collection of classes. Second, a package participates in Java’s access control mechanism. Classes defined within a package can be made private to that package and not accessible by code outside the package. Thus, the package provides a means by which classes can be encapsulated. Let’s examine each feature a bit more closely.

In general, when you name a class, you ...