<dependency>
<groupId>org.hibernate.validator</groupId>
<artifactId>hibernate-validator</artifactId>
<version>6.2.0.Final</version>
</dependency>
public class User {
@NotNull
private String username;
// Getters and setters
}
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
Validator validator = factory.getValidator();
User user = new User();
Set<ConstraintViolation<User>> violations = validator.validate(user);
if (violations.isEmpty()) {
} else {
for (ConstraintViolation<User> violation : violations) {
System.out.println(violation.getMessage());
}
}
<validation-config xmlns="http://xmlns.jcp.org/xml/ns/validation/configuration"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/configuration
http://xmlns.jcp.org/xml/ns/validation/configuration/validation-configuration-2.0.xsd">
<default-provider>org.hibernate.validator.HibernateValidator</default-provider>
</validation-config>
