Java Annotations – Starting Java 5.0

Other APIs require “side files” to be maintained in parallel with programs. For example JavaBeans requires a BeanInfo class to be maintained in parallel with a bean, and Enterprise JavaBeans (EJB) requires a deployment descriptor. It would be more convenient and less error-prone if the information in these side files were maintained as annotations in the program itself.

The Anwer — Java Annotations…

Java platform has always had various ad hoc annotation mechanisms. For example the transient modifier is an ad hoc annotation indicating that a field should be ignored by the serialization subsystem, and the @deprecated javadoc tag is an ad hoc annotation indicating that the method should no longer be used. As of release 5.0, the platform has a general purpose annotation (also known as metadata) facility that permits you to define and use your own annotation types. The facility consists of a syntax for declaring annotation types, a syntax for annotating declarations, APIs for reading annotations, a class file representation for annotations, and an annotation processing tool.

Useful resource on Annotation

— Defining Annotation and Annotating your class

—- Accessing Anotation using Reflection

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1 Comment

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One response to “Java Annotations – Starting Java 5.0

  1. Mr. President

    Thanks for adding a reference to my post(http://technicalmumbojumbo.wordpress.com/2008/01/13/java-custom-annotations/47) in your article.

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