The Java API is organized by packages
. Each package contains related classes and interfaces. A package is used to define a separate naming context
Packages allow multiple classes and interfaces to have the same name. Classes and interfaces with the same name are defined in separate packages. Suppose that both
you and I want to define a class named
I can define my class in a package named
and you can define your class in a package named
A package naming convention
can help assure that you are creating a unique package name.
statement is used to identify the package with which the classes and interfaces of a source code file should be associated.
Its syntax is as follows:
If a package statement is included in a source code file, it must appear as the first non-blank, non-comment line in the file.
If a source code file does not have a
statement, then the file's classes and interfaces are put in the default (no name) package.
All classes and interfaces of the same package can be referenced without having to identify their package name.
However, to reference the classes and interfaces of other packages, you either need to
prepend their package name
, or import them using the
statement. Its syntax
takes the following three forms:
The first form imports all classes and interfaces of the package named packageName
. The other forms are used to import
specific classes and interfaces.
Click the Quiz link below to check your understanding of packages and compilation units.
Packages Compilation Units - Quiz