{"id":1683,"date":"2011-03-16T11:50:19","date_gmt":"2011-03-16T06:20:19","guid":{"rendered":"http:\/\/JitendraZaa.com\/blog\/?p=1683"},"modified":"2011-03-16T11:50:19","modified_gmt":"2011-03-16T06:20:19","slug":"reading-and-writing-custom-annotation","status":"publish","type":"post","link":"https:\/\/www.jitendrazaa.com\/blog\/java\/reading-and-writing-custom-annotation\/","title":{"rendered":"Reading and Writing Custom Annotation"},"content":{"rendered":"

We have already discussed the basics of annotation and Meta Annotation in JAVA<\/a>. \u00a0In this article i will explain how to read and write the custom annotation in JAVA.<\/p>\n

To define custom Annotation, keyword interface <\/strong>is used preceded by @. Like interface, it also has the method declaration.
\nTo make topic easy, lets I want to create the annotation CopyRight<\/p>\n

\npackage com.G2.Annotations;\nimport java.lang.annotation.Retention;\nimport java.lang.annotation.RetentionPolicy;\n\n@Retention(value=RetentionPolicy.RUNTIME)\npublic @interface CopyRight {\n\tpublic String owner();\n\tpublic String location();\n\tpublic String year();\n}\n<\/pre>\n
To use this annotation in our class, we should use like:<\/p>\n
\npackage com.G2.Annotations;\n\n@CopyRight(location="Mumbai",owner="Jitendra Zaa",year="2011")\npublic class TestAnnotations {\n}\n<\/pre>\n
Annotation can also have the default values<\/strong> while declaration.
\nExample:<\/p>\n
\npackage com.G2.Annotations;\nimport java.lang.annotation.Retention;\nimport java.lang.annotation.RetentionPolicy;\n\n@Retention(value=RetentionPolicy.RUNTIME)\npublic @interface CopyRight  {\n\tpublic String owner() default "Jitendra Zaa";\n\tpublic String location() default "Mumbai";\n\tpublic String year() default "2011";\n}\n<\/pre>\n
Program to read the Annotations:<\/strong><\/p>\n
\npackage com.G2.Annotations;\n\nimport java.lang.annotation.Annotation;\n\n@CopyRight(location="Mumbai",owner="Jitendra Zaa",year="2011")\npublic class TestAnnotations {\n\n\t\/**\n\t * @param args\n\t *\/\n\tpublic static void main(String[] args) throws ClassNotFoundException {\n\t\tTestAnnotations obj = new TestAnnotations();\n\t\tobj.display();\n\t}\n\n\tpublic void display() throws ClassNotFoundException\n\t{\n\t\tAnnotation[] annotations = TestAnnotations.class.getAnnotations();\n\t\tSystem.out.println(annotations.length);\n\t\tfor(Annotation a : annotations)\n\t\t{\n\t\t\tCopyRight r = (CopyRight)a;\n\t\t\tSystem.out.println("Location Value in Annotation : "+r.location());\n\t\t\tSystem.out.println("Owner Value in Annotation : "+r.owner());\n\t\t\tSystem.out.println("Year Value in Annotation : "+r.year());\n\t\t}\n\n\t}\n}\n<\/pre>\n
Output:<\/p>\n
1
\nLocation Value in Annotation : Mumbai
\nOwner Value in Annotation : Jitendra Zaa
\nYear Value in Annotation : 2011<\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"
Article on Reading and Writing Custom Annotation with example<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"advanced_seo_description":"","jetpack_seo_html_title":"","jetpack_seo_noindex":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"jz_research_post":"","_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[3],"tags":[36],"class_list":["post-1683","post","type-post","status-publish","format-standard","hentry","category-java","tag-annotation"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack-related-posts":[{"id":1676,"url":"https:\/\/www.jitendrazaa.com\/blog\/java\/meta-annotation-annotate-other-annotation\/","url_meta":{"origin":1683,"position":0},"title":"Meta Annotation – annotate other annotation","author":"Jitendra","date":"March 16, 2011","format":false,"excerpt":"What is Meta Annotation and its usage in JAVA","rel":"","context":"In "JAVA"","block_context":{"text":"JAVA","link":"https:\/\/www.jitendrazaa.com\/blog\/category\/java\/"},"img":{"alt_text":"Inbuilt Annotation and Meta Annotations in JAVA","src":"https:\/\/i0.wp.com\/jitendrazaa.com\/blog\/wp-content\/uploads\/2011\/03\/Inbuilt-Annotation-and-Meta-Annotations-in-JAVA.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":1959,"url":"https:\/\/www.jitendrazaa.com\/blog\/java\/servlet\/create-servlet-using-annotation\/","url_meta":{"origin":1683,"position":1},"title":"Create Servlet using Annotation – Servlet 3.0","author":"Jitendra","date":"April 13, 2011","format":false,"excerpt":"Create the Servlet without any deployment descriptor. 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