The Java Tutorials have been written for JDK 8. Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.
See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.
To create a package for a type, put a package statement as the first statement in the source file that contains the type (class, interface, enumeration, or annotation type).
To use a public type that's in a different package, you have three choices: (1) use the fully qualified name of the type, (2) import the type, or (3) import the entire package of which the type is a member.
The path names for a package's source and class files mirror the name of the package.
You might have to set your CLASSPATH so that the compiler and the JVM can find the .class files for your types.