|
Rectangle
class when there is already a Rectangle class in
the java.awt package. Still, the compiler allows both
classes to have the same name if they are in different
packages. The fully qualified name of each Rectangle class includes
the package name. That is, the fully qualified name of the Rectangle
class in the graphics package is graphics.Rectangle,
and the fully qualified name of the Rectangle class
in the java.awt package is java.awt.Rectangle.
This works well unless two independent programmers use the same name for their packages. What prevents this problem? Convention.
Companies use their reversed Internet domain name to begin their package
names—for example, com.example.orion
for a package named orion created by a programmer at example.com.
Name collisions that occur within
a single company need to be handled by convention within that company,
perhaps by including the
region or the project name after the company name
(for example, com.company.region.package).
Packages in the Java language itself begin with java. or javax.
In some cases, the internet domain name may not be a valid package name. This can occur if the domain name contains a hyphen or other special character, if the package name begins with a digit or other character that is illegal to use as the beginning of a Java name, or if the package name contains a reserved Java keyword, such as "int". In this event, the suggested convention is to add an underscore. For example:
| Domain Name | Package Name Prefix |
|---|---|
| clipart-open.org | org.clipart_open |
| free.fonts.int | int_.fonts.free |
| poetry.7days.com | com._7days.poetry |
|
