RetentionPolicy in Java

java.lang.annotation.RetentionPolicy

Annotation retention policy. The constants of this enumerated type describe the various policies for retaining annotations. They are used in conjunction with the Retention meta-annotation type to specify how long annotations are to be retained.

Declaration

public enum RetentionPolicy {

    SOURCE,

    CLASS,

    RUNTIME
}

1. SOURCE

java.lang.annotation.RetentionPolicy.SOURCE

 Annotations are to be discarded by the compiler.

2. CLASS

java.lang.annotation.RetentionPolicy.CLASS

Annotations are to be recorded in the class file by the compiler but need not be retained by the VM at run time. This is the default behavior.

3. RUNTIME

java.lang.annotation.RetentionPolicy.RUNTIME

Annotations are to be recorded in the class file by the compiler and retained by the VM at run time, so they may be read reflectively.

Some other classes/interfaces of java.lang.annotation

Native: Indicates that a field defining a constant value may be referenced from native code.

Inherited: Indicates that an annotation type is automatically inherited.

IncompleteAnnotationException: Thrown to indicate that a program has attempted to access an element of an annotation type that was added to the annotation type definition after the annotation was compiled (or serialized). 

AnnotationFormatError: Thrown when the annotation parser attempts to read an annotation from a class file and determines that the annotation is malformed.

ElementType: The constants of this enumerated type provide a simple classification of the syntactic locations where annotations may appear in a Java program.

Documented: If the annotation @Documented is present on the declaration of an annotation type A, then any @A annotation on an element is considered part of the element's public contract.

AnnotationTypeMismatchException: Thrown to indicate that a program has attempted to access an element of an annotation whose type has changed after the annotation was compiled.

Annotation: The common interface is extended by all annotation types.

Repeatable: The annotation type is java.lang.annotation.Repeatable is used to indicate that the annotation type whose declaration it(meta-)annotates is repeatable.

Retention: Indicates how long annotations with the annotated type are to be retained. If no Retention annotation is present on an annotation-type declaration, the retention policy defaults to RetentionPolicy.CLASS.

RetentionPolicy: Annotation retention policy. The constants of this enumerated type describe the various policies for retaining annotations.

Target: Indicates the contexts in which an annotation type is applicable.