Sun Microsystem added the features like annotation to make the development easier and more efficient in jdk 5.

Java Developers Desk- Annotations

       

 

1. An Introduction to Annotations
   Sun Microsystem added the features like annotation to make the development easier and more efficient in jdk 5. The main objective to develop the annotations is to make the development easier. Annotations behaves like the meta. The literal meaning of meta data is data about data. Java also signifies this meaning. Annotations are like meta data, means you are free to add your code and can also apply them to variables, parameters, fields type declarations, methods and constructors.
     
2. Fundamentals of annotations
   While going through the annotations you should consider two things. The first one is the ?annotation? itself and second one is the ?annotations types?. An annotation is the meta tag, used to give some life to the code you are using. While annotation type is used to define annotations so that you can use them while creating your own custom annotations. An annotation type definition appends an ?at? @ sign at the start of the interface keyword with the annotation name. On the other hand, an annotation includes the ?at? @ sign followed by the annotation type.

Read more information at:

http://www.javajazzup.com/issue7/page7.shtml

 

Recommend the tutorial