Doubt in annotations.

Hi,

We have a annotation @Deprecated.

if i use this annotation @Deprecated before a method, the compiler will throw the following warning

Note: Dep.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.

the code of Deprecated.java is

/* * @(#)Deprecated.java 1.5 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.lang; import java.lang.annotation.*; /** * A program element annotated @Deprecated is one that programmers * are discouraged from using, typically because it is dangerous, * or because a better alternative exists. Compilers warn when a * deprecated program element is used or overridden in non-deprecated code. * * @author Neal Gafter * @version 1.5, 11/17/05 * @since 1.5 */ @Documented @Retention(RetentionPolicy.RUNTIME) public @interface Deprecated { }


May I know, where will be the deprecation error message is configured and how it is getting display ?

In the compiler.

Annotations represent metadata that can be used by an annotation processor. The Java compiler has plugins to handle annotations. So a compiler plugin will output the message. I guess it can't be configured.

There are three annotations in package java.lang: Override, Deprecated and SuppressWarnings. These are the only annotations with special compiler support. I believe that's the reason they are not located in package java.lang.annotation, like other "system" annotations like Documented, Inherited, Retention and Target.