Interfaces - The Java Language Specification - page 284

If an annotation a corresponds to a type T , and T has a (meta-)annotation m that corresponds
to java.lang.annotation.Retention , then:
• If m has an element whose value is java.lang.annotation.RetentionPolicy.SOURCE , then a
Java compiler must ensure that a is not present in the binary representation of the
class or interface in which a appears.
• If m has an element whose value is java.lang.annotation.RetentionPolicy.CLASS or
java.lang.annotation.RetentionPolicy.RUNTIME , then a Java compiler must ensure that a
is represented in the binary representation of the class or interface in which a ap-
pears, unless m annotates a local variable declaration.
An annotation on a local variable declaration is never retained in the binary repres-
entation.
In addition, if m has an element whose value is
java.lang.annotation.RetentionPolicy.RUNTIME , the reflection libraries of the Java SE
platform must make a available at run time.
If T does not have a (meta-)annotation m that corresponds to java.lang.annotation.Retention ,
then a Java compiler must treat T as if it does have such a meta-annotation m with an ele-
ment whose value is java.lang.annotation.RetentionPolicy.CLASS .
9.6.3.3. @Inherited
The annotation type java.lang.annotation.Inherited is used to indicate that annotations on a class
C corresponding to a given annotation type are inherited by subclasses of C .
9.6.3.4. @Override
Programmers occasionally overload a method declaration when they mean to override it,
leading to subtle problems. The annotation type Override supports early detection of such
problems.
The classic example concerns the equals method. Programmers write the following in
class Foo :
public boolean equals(Foo that) { ... }
when they mean to write:
public boolean equals(Object that) { ... }
This is perfectly legal, but class Foo inherits the equals implementation from Object ,
which can cause some very subtle bugs.