Runtime annotation checks via reflection

suggest change

Java’s Reflection API allows the programmer to perform various checks and operations on class fields, methods and annotations during runtime. However, in order for an annotation to be at all visible at runtime, the RetentionPolicy must be changed to RUNTIME, as demonstrated in the example below:

@interface MyDefaultAnnotation {


@interface MyRuntimeVisibleAnnotation {


public class AnnotationAtRuntimeTest {

    static class RuntimeCheck1 {
    static class RuntimeCheck2 {
    public static void main(String[] args) {
        Annotation[] annotationsByType = RuntimeCheck1.class.getAnnotations();
        Annotation[] annotationsByType2 = RuntimeCheck2.class.getAnnotations();

        System.out.println("default retention: " + Arrays.toString(annotationsByType));
        System.out.println("runtime retention: " + Arrays.toString(annotationsByType2));

Feedback about page:

Optional: your email if you want me to get back to you:

Table Of Contents