Target Annotation 

The Annotation defined is by default applicable to all java constructs such as class, interface, enumerations, constructors, fields, methods, method parameters, local variables, packages and Annotations. However we can restrict this behavior by specifying target with @Target annotation.

The possible targets are listed below,

• ElementType.TYPE
  Applicable to Java classes, interfaces, enumerations and Annotations.
• ElementType.FIELD
  Applicable to Java fields.
• ElementType.METHOD
  Applicable to Java methods.
• ElementType.PARAMETER
  Applicable to Java method parameters.
• ElementType.CONSTRUCTOR
  Applicable to Java class constructors.
• ElementType.LOCAL_VARIABLE
  Applicable to Java local variables.
• ElementType.ANNOTATION_TYPE
  Applicable to Java annotations.
• ElementType.PACKAGE
  Applicable to Java packages.

A simple Annotation targeted to java types is shown below,

File Name  :   com/bethecoder/tutorials/annotations/targets/Author.java  Author  :   Sudhakar KV Email  :   [email protected]

package com.bethecoder.tutorials.annotations.targets; import java.lang.annotation.ElementType; import java.lang.annotation.Target; /**  * Permitted types for annotation attributes  *   * 1. primitive type  * 2. String  * 3. Class  * 4. annotation   * 5. enumeration   * 6. 1-dimensional arrays  */ @Target(ElementType.TYPE) public @interface Author {   String name();   String creationDate(); }

We can use this Annotation only with classes, interfaces, enumerations and Annotations. Its usage is shown below,

File Name  :   com/bethecoder/tutorials/annotations/targets/Source.java  Author  :   Sudhakar KV Email  :   [email protected]

package com.bethecoder.tutorials.annotations.targets; @Author(name = "Author1", creationDate="01/01/2500") public class Source {   private int fieldOne;   private String fieldTwo;      public Source(int fieldOne, String fieldTwo) {     super();     this.fieldOne = fieldOne;     this.fieldTwo = fieldTwo;   }   public int getFieldOne() {     return fieldOne;   }      public void setFieldOne(int fieldOne) {     this.fieldOne = fieldOne;   }      public String getFieldTwo() {     return fieldTwo;   }      public void setFieldTwo(String fieldTwo) {     this.fieldTwo = fieldTwo;   }    }