A package is a group of related classes, interfaces, annotations and enumerations bundled together. Henceforth, when we refer to classes in this chapter we mean to include other components such as interfaces, annotations and enumerations, unless stated otherwise.
Packages are like containers that provide your classes a name space. For example,
a package allows you to create two classes named Scanner. You simply need to
store the classes in different packages. However, the class names should be
unique within their respective packages.
A package provides a name space and visibility control to your classes. You can tell which classes are available to the world outside your package.
Packages are organized in a hierarchical fashion. When you want to use a class from a different package, you need to import it.
So far in this book, all the classes you created were stored in the default package. Which means you had to provide a unique name for each class to avoid name conflicts. Without packages you would soon run out of relevant, convenient and descriptive names for your classes.
Further, without packages you would need to make sure that the name you choose for your classes are different from the class names chosen by other programmers.
In fact, the Java API consists of thousands of classes. It would be impossible to find a unique name for each of these classes. This is why, the Java API is ogranized as packages.