docs/org.eclipse.jst.j2ee.doc.user/topics/tdefiningannotations.html - gerrit/jeetools/webtools.javaee - Git at Google

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 <h1 class="id_title">Defining and using annotations</h1>


 <div class="id_taskbody"><p class="id_shortdesc">You can use the @Interface annotation
 to define your own annotation definition.</p>

 <div class="id_context"> <p class="anchor_topictop" />
 <p><strong>Defining
 your own annotations</strong></p>
 </div>


 <div class="p"><span>Use the @Interface annotation to define your own annotation definition:</span>
  <div class="p"><ul>
 <li>Annotation definitions resemble interface definitions</li>

 <li>Annotation method declarations have neither parameters nor <samp class="codeph">throws</samp> clauses,
 and return one of the following elements:<ul>
 <li>primitives</li>

 <li>String</li>

 <li>Class</li>

 <li>enum</li>

 <li>array of the above types</li>

 </ul>
 </li>

 <li>Methods may have default values</li>

 </ul>
 </div>
 <div class="p"><pre>public @interface CreatedBy{
      String name();
      String date();
      boolean contractor() default false;
 }          </pre>
 <pre>@CreatedBy(name = "Mary Smith",date="02/02/2008");
 public class MyClass{....}         </pre>
 </div>
 </div>


 <div class="id_postreq"><div class="p"><strong>Meta-annotations</strong>: Meta-annotations
 (annotations of annotations) provide additional information on how an annotation
 should be used:<ul>
 <li>@Target<ul>
 <li>Restricts the use of an annotation</li>

 <li>Single argument must be from Enum ElementType <ul>
 <li>{TYPE, FIELD,METHOD, PARAMETER, CONSTRUCTOR, LOCAL_VARIABLE, ANNOTATION_TYPE}</li>

 </ul>
 </li>

 </ul>
 </li>

 <li>@Retention<ul>
 <li>Indicates where the annotation information will be retained</li>

 <li>Single argument must be from Enum RetentionPolicy<ul>
 <li>{SOURCE, CLASS, RUNTIME}</li>

 </ul>
 </li>

 </ul>
 </li>

 <li>@Documented<ul>
 <li>Marker for annotations that should be included in Javadoc</li>

 </ul>
 </li>

 <li>@Inherited<ul>
 <li>marker for Type annotations that are to be inherited by subtypes</li>

 </ul>
 </li>

 </ul>
 <strong>Other built-in annotations</strong>: <ul>
 <li>@Overrides<ul>
 <li>Applied to a method</li>

 <li>Indicates that the compiler should generate an error if the method does
 not actually override a superclass method.</li>

 </ul>
 </li>

 <li>@Deprecated<ul>
 <li>Applied to a method</li>

 <li>Indicates that the compiler should generate a warning when the method
 is used externally</li>

 </ul>
 </li>

 <li>@SuppressWarnings<ul>
 <li>Applies to a type or a method</li>

 <li>Indicates that the compiler should supress warnings for that element and
 all subelements<div class="p"><pre>@Deprecated
 public void oldMethod() {...}

 @ SupressWarnings
 public void yesIknowIuseDeprecatedMethods() {...}</pre>
 </div>
 </li>

 </ul>
 </li>

 </ul>
 </div>
 <p class="anchor_topicbottom" />
 </div>

 </div>

 <div>
 <ul class="ullinks">
 <li class="ulchildlink"><strong><a href="../topics/ctypesofanno.html">Types of annotations</a></strong><br />
 Java EE 6 and Java EE 5 define a number of types or groups of annotations, defined in a number of Java Specification Requests (JSRs).</li>
 </ul>

 <div class="familylinks">
 <div class="parentlink"><strong>Parent topic:</strong> <a href="../topics/cannotations.html" title="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.">Java EE 5 and Java EE 6 support for annotations</a></div>
 </div>
 </div>

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	<meta name="DC.Title" content="Defining and using annotations" />
	<meta name="abstract" content="You can use the @Interface annotation to define your own annotation definition." />
	<meta name="description" content="You can use the @Interface annotation to define your own annotation definition." />
	<meta content="Java EE 5, annotations, defining" name="DC.subject" />
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	<title>Defining and using annotations</title>
	</head>
	<body id="tjimpear"><a name="tjimpear"><!-- --></a>


	<h1 class="id_title">Defining and using annotations</h1>



	<div class="id_taskbody"><p class="id_shortdesc">You can use the @Interface annotation
	to define your own annotation definition.</p>

	<div class="id_context"> <p class="anchor_topictop" />
	<p><strong>Defining
	your own annotations</strong></p>
	</div>


	<div class="p"><span>Use the @Interface annotation to define your own annotation definition:</span>
	<div class="p"><ul>
	<li>Annotation definitions resemble interface definitions</li>

	<li>Annotation method declarations have neither parameters nor <samp class="codeph">throws</samp> clauses,
	and return one of the following elements:<ul>
	<li>primitives</li>

	<li>String</li>

	<li>Class</li>

	<li>enum</li>

	<li>array of the above types</li>

	</ul>
	</li>

	<li>Methods may have default values</li>

	</ul>
	</div>
	<div class="p"><pre>public @interface CreatedBy{
	String name();
	String date();
	boolean contractor() default false;
	} </pre>
	<pre>@CreatedBy(name = "Mary Smith",date="02/02/2008");
	public class MyClass{....} </pre>
	</div>
	</div>


	<div class="id_postreq"><div class="p"><strong>Meta-annotations</strong>: Meta-annotations
	(annotations of annotations) provide additional information on how an annotation
	should be used:<ul>
	<li>@Target<ul>
	<li>Restricts the use of an annotation</li>

	<li>Single argument must be from Enum ElementType <ul>
	<li>{TYPE, FIELD,METHOD, PARAMETER, CONSTRUCTOR, LOCAL_VARIABLE, ANNOTATION_TYPE}</li>

	</ul>
	</li>

	</ul>
	</li>

	<li>@Retention<ul>
	<li>Indicates where the annotation information will be retained</li>

	<li>Single argument must be from Enum RetentionPolicy<ul>
	<li>{SOURCE, CLASS, RUNTIME}</li>

	</ul>
	</li>

	</ul>
	</li>

	<li>@Documented<ul>
	<li>Marker for annotations that should be included in Javadoc</li>

	</ul>
	</li>

	<li>@Inherited<ul>
	<li>marker for Type annotations that are to be inherited by subtypes</li>

	</ul>
	</li>

	</ul>
	<strong>Other built-in annotations</strong>: <ul>
	<li>@Overrides<ul>
	<li>Applied to a method</li>

	<li>Indicates that the compiler should generate an error if the method does
	not actually override a superclass method.</li>

	</ul>
	</li>

	<li>@Deprecated<ul>
	<li>Applied to a method</li>

	<li>Indicates that the compiler should generate a warning when the method
	is used externally</li>

	</ul>
	</li>

	<li>@SuppressWarnings<ul>
	<li>Applies to a type or a method</li>

	<li>Indicates that the compiler should supress warnings for that element and
	all subelements<div class="p"><pre>@Deprecated
	public void oldMethod() {...}

	@ SupressWarnings
	public void yesIknowIuseDeprecatedMethods() {...}</pre>
	</div>
	</li>

	</ul>
	</li>

	</ul>
	</div>
	<p class="anchor_topicbottom" />
	</div>

	</div>

	<div>
	<ul class="ullinks">
	<li class="ulchildlink"><strong><a href="../topics/ctypesofanno.html">Types of annotations</a></strong><br />
	Java EE 6 and Java EE 5 define a number of types or groups of annotations, defined in a number of Java Specification Requests (JSRs).</li>
	</ul>

	<div class="familylinks">
	<div class="parentlink"><strong>Parent topic:</strong> <a href="../topics/cannotations.html" title="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.">Java EE 5 and Java EE 6 support for annotations</a></div>
	</div>
	</div>

	</body>
	</html>