how to say this field has email annotation from outside

Question

@NotNull(message = "emailAddress is mandatory")
@NotEmpty(message = "emailAddress cannot be empty")
@Email(message = "Invalid Email")
private String emailAddress;

I just want to know from outside , emailAdress has Email annotation. Is there any way that we can say it is an email annotaion?

Answer 1

You can use reflection for this. The following test passes:

 public class MyTest {

    @Test
    public void test() throws NoSuchFieldException {
        HasEmailAddressValidator hasEmailAddressValidator = new HasEmailAddressValidator();
        boolean result = hasEmailAddressValidator.hasEmailAddress(MyClass.class);

        assertTrue(result);
    }

    @NoArgsConstructor
    static
    class HasEmailAddressValidator {
        public boolean hasEmailAddress(Class<?> clazz) throws NoSuchFieldException {
            return clazz.getDeclaredField("email").isAnnotationPresent(Email.class);
        }
    }

    @Data
    static
    class MyClass {
        @Email(message = "this is an email address")
        private String email;
    }
}