Get list of fields with annotation, by using reflection

Question

I create my annotation

public @interface MyAnnotation {
}

I put it on fields in my test object

public class TestObject {

          


        

Answer 1

You need to mark the annotation as being available at runtime. Add the following to your annotation code.

@Retention(RetentionPolicy.RUNTIME)
public @interface MyAnnotation {
}

Answer 2

/**
 * @return null safe set
 */
public static Set<Field> findFields(Class<?> classs, Class<? extends Annotation> ann) {
    Set<Field> set = new HashSet<>();
    Class<?> c = classs;
    while (c != null) {
        for (Field field : c.getDeclaredFields()) {
            if (field.isAnnotationPresent(ann)) {
                set.add(field);
            }
        }
        c = c.getSuperclass();
    }
    return set;
}