Java EE 5 and Java EE 6 support for annotations

The goal of Java™ EE 5 and Java EE 6 platform development is to minimize the number of artifacts that you have to create and maintain, thereby simplifying the development process. Java EE 5 and Java EE 6 support the injection of annotations into your source code, so that you can embed resources, dependencies, services, and life-cycle notifications in your source code, without having to maintain these artifacts elsewhere.

An annotation is a modifier or Metadata tag that provides additional data to Java classes, interfaces, constructors, methods, fields, parameters, and local variables. Annotations replace boilerplate code, common code that is required by certain applications. For example, an annotation can replace the paired interface and implementation required for a Web service. Annotations can also replace additional files that programs require, which are maintained separately. By using an annotation, this separate file is no longer required. For example, annotations can replace the need for a separately maintained deployment descriptor for JavaBeans™.

Annotations

Replace descriptors for most purposes
Remove the need for marker interfaces (like java.rmi.Remote)
Allow application settings to be visible in the component they affect

Java EE 5 provides annotations for the following tasks, among others:

Developing Enterprise JavaBean applications
Defining and using Web services
Mapping Java technology classes to XML
Mapping Java technology classes to databases
Mapping methods to operations
Specifying external dependencies
Specirying deployment information, including security attributes

Java EE 5 defines a number of annotations that can be injected into your source code. To declare an annotation, you simply precede the keyword with an "at" sign (@).

package com.ibm.counter;

import javax.ejb.Stateless;

@Stateless

public class CounterBean {

}

For more information about the categories of annotations that Java EE 5 and Java EE 6 support, see Types of annotations.