Annotations - The Java Programming Language - page 573

15.1. A Simple Annotation Example
Consider an informal, comment-based class preamble:
/*-------------------------------
Created: Jan 31 2005
Created By: James Gosling
Last Modified: Feb 9 2005
Last Modified By: Ken Arnold
Revision: 3
---------------------------------*/
public class Foo {
// ...
}
You can define an annotation type that can hold all of the desired inform-
ation:
@interface ClassInfo {
String created();
String createdBy();
String lastModified();
String lastModifiedBy();
int revision();
}
An annotation type is a special kind of interface, designated by the @
character preceding the interface keyword. [1] Annotations are applied to
program elements, such as a class or field declaration. What appear to be
methods in the annotation type are actually special annotation element
declarations. An annotation element is rather like a field, and has a value
for each program element that has that type of annotation. So a ClassInfo
annotation contains four string elements and one int element. When you
annotate (apply an annotation to) a program element, you supply val-