How to annotate java package and reflect metadata

Question

I would like to annotite java package using simple annotation:

@Target(ElementType.PACKAGE) public @interface Related { int apiVersion() default 0; }

However when I try to add it to any package I've got compilation error

Error:(1, 14) java: cannot find symbol symbol: class Related location: package com.test.xxx

Any help appreciated!

EDIT

After searching a bit I found also this kind of error

Error:(1, 1) java: package annotations should be in file package-info.java

thank you for quick answer! no, I found another one - Error:(1, 1) java: package annotations should be in file package-info.java — user6719582
– user6719582, Commented Aug 15, 2016 at 23:13

vsminkov · Accepted Answer · 2016-08-15 23:21:49Z

To be able to place annotation on package you should create package-info.java file which should contain package definition like this:

@Related package tld.some.name;

To be able to reflect reflect package you also need to set up RetentionPolicy.RUNTIME

@Retention(RetentionPolicy.RUNTIME) @Target(ElementType.PACKAGE) public @interface Related { // stuff... }

And then you can finally reflect package:

SomeClassInPackage.class.getPackage().getAnnotation(Related.class)

You can also reflect package by name using java.lang.Package

Package.getPackage("tld.some.name").getAnnotation(Related.class)

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