[spricket]

Java only works in classes :) . They're actually the compilation unit as well so no way around it. (Files are compiled a .class file at a time from single source files)

Adding another example, JPA MetaModel generator that allows you to make strongly typed calls in ORM.

Basically, it let's you generate code at compile time that's seamlessly integrated into the existing code. So it's generated code that still gives you IDE autocomplete support etc.