Java - How to find Annotations On Enum Constants?

Java Reflection Java Enum Java Annotations Java 

Following example shows how to find annotations on enum constants by reflection.

package com.logicbig.example;

import java.lang.annotation.*;
import java.lang.reflect.Field;
import java.util.LinkedHashMap;
import java.util.Map;


public class EnumFieldAnnotationExample {

    public static <E extends Enum, A extends Annotation> Map<E, A> getEnumsAnnotatedWith(
            Class<E> enumClass,
            Class<A> annotationType) {

        Map<E, A> map = new LinkedHashMap<>();
        if (enumClass == null || annotationType == null) {
            return map;
        }
        for (E enumConstant : enumClass.getEnumConstants()) {
            Field declaredField = null;
            try {
                declaredField = enumClass.getDeclaredField(enumConstant.name());
            } catch (NoSuchFieldException e) {
                //this exception will never be thrown
                e.printStackTrace();
            }
            if (declaredField != null) {//should never be null
                A annotation = declaredField.getAnnotation(annotationType);
                if (annotation != null) {
                    map.put(enumConstant, annotation);
                }
            }
        }
        return map;
    }

    public static void main(String[] args) {
        Map<Day, Weekend> map = getEnumsAnnotatedWith(Day.class, Weekend.class);
        map.forEach((k, v) -> System.out.printf("enum= %s, annotation= %s%n", k, v));
    }

    public enum Day {
        Monday,
        Tuesday,
        Wednesday,
        Thursday,
        Friday,
        @Weekend
        Saturday,
        @Weekend
        Sunday
    }

    @Target({ElementType.FIELD})
    @Retention(RetentionPolicy.RUNTIME)
    public @interface Weekend {}
}

enum= Saturday, annotation= @com.logicbig.example.EnumFieldAnnotationExample$Weekend()
enum= Sunday, annotation= @com.logicbig.example.EnumFieldAnnotationExample$Weekend()