<dependency>
<groupId>org.hibernate.validator</groupId>
<artifactId>hibernate-validator</artifactId>
<version>6.2.0.Final</version>
</dependency>
import javax.validation.Constraint;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import javax.validation.Payload;
import javax.validation.constraints.Pattern;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
@Constraint(validatedBy = ValidName.Validator.class)
public @interface ValidName {
String message() default "";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
class Validator implements ConstraintValidator<ValidName, String> {
@Override
public boolean isValid(String name, ConstraintValidatorContext context) {
return name != null && name.length() > 1 && name.length() < 50;
}
}
}
public class User {
private String name;
// setter and getter methods
}
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
import javax.validation.ConstraintViolation;
import java.util.Set;
public class Main {
public static void main(String[] args) {
User user = new User();
user.setName("John123");
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
Validator validator = factory.getValidator();
Set<ConstraintViolation<User>> violations = validator.validate(user);
if (!violations.isEmpty()) {
for (ConstraintViolation<User> violation : violations) {
System.out.println(violation.getMessage());
}
}
}
}
