Tutorial Description - Package and class declarations
A package represents a group of classes.
A package represents a group of classes. A package statement should be the first valid statement in the source file. If there is no package statement, the classes in the source file belong to the default unnamed package, or else they belong to the named package. Only one package statement is allowed in a source file.
In a source file, there can be only one public class, and the name of the file should match that of the class. An import statement allows you to use a class directly instead of referring to it using its fully qualified name. Import statements must come after any package statement and before the class declarations, as shown below: