public class User {
@NotNull
@Size(min = 5, max = 20)
private String username;
@NotNull
@Email
private String email;
// getter and setter methods
}
public class Main {
public static void main(String[] args) {
User user = new User();
user.setUsername("john");
user.setEmail("invalidemail");
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
Validator validator = factory.getValidator();
Set<ConstraintViolation<User>> violations = validator.validate(user);
for (ConstraintViolation<User> violation : violations) {
System.out.println(violation.getMessage());
}
}
}
