Java implementations map package and subpackage names to same-named directories. For example, an implementation would map graphics to a directory named graphics .

java.lang: A collection of language-related classes, such as Object and String, organized in the java package’s lang subpackage; java.lang.ref: A collection of reference-related language classes ...

reference the package and class name java.util.Scanner in your code; To use the Java Scanner for user input, either import the java.util package, or use the full package and class name, ...

That three percent included packages, methods, and class names. But those declarations—like starting a function with package java.lang —can only be used in certain ways.