can I use any annotation on custom annotation

Question

As, I know we can apply annotation like @Target , @Retention , @Documented on custom annotation.

But recently I saw @Constraint applied on custom annotation.

Can We use any annotation on custom annotation? how it works?

Answer 1

Each annotation can only be written in certain places. Those places are determined by the @Target meta-annotation on the annotation's definition. For example, if an annotation is declared as

    @Target(ElementType.ANNOTATION_TYPE)
    public @interface MyAnnotation {
        ...
    }

then @MyAnnotation may only be written on annotation declarations. You cannot write @MyAnnotation on a field or class declaration, or on a type use. An annotation that may be written on annotation declarations is called a meta-annotation.

You can learn more about annotations from the Java annotations tutorial .