<dependency>
<groupId>jakarta.validation</groupId>
<artifactId>jakarta.validation-api</artifactId>
<version>2.0.2</version>
</dependency>
public class User {
private String username;
private String password;
}
public class UserValidator implements ConstraintValidator<ValidUser, User> {
@Override
public boolean isValid(User user, ConstraintValidatorContext context) {
}
}
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = UserValidator.class)
public @interface ValidUser {
}
@ValidUser
public class User {
}
**User.java**
@ValidUser
public class User {
private String username;
private String password;
}
**ValidUser.java**
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = UserValidator.class)
public @interface ValidUser {
}
**UserValidator.java**
public class UserValidator implements ConstraintValidator<ValidUser, User> {
@Override
public boolean isValid(User user, ConstraintValidatorContext context) {
}
}
**Main.java**
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
public class Main {
public static void main(String[] args) {
User user = new User();
user.setUsername("John");
user.setPassword("1234567");
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());
}
}
}
