We wouldn't want our user to enter invalid or empty information and that's why we will need to add some validation logic to our ProfileForm.
package masterspringmvc4.profile;
import org.hibernate.validator.constraints.Email;
import org.hibernate.validator.constraints.NotEmpty;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Past;
import javax.validation.constraints.Size;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
public class ProfileForm {
@Size(min = 2)
private String twitterHandle;
@Email
@NotEmpty
private String email;
@NotNull
private Date birthDate;
@NotEmpty
private List<String> tastes = new ArrayList<>();
}As you can see, we added a few validation constraints. These annotations come from the JSR-303 specification, which specifies bean validation. The most popular implementation of this specification is hibernate-validator, which is included in Spring Boot...