Hibernate Validator with Example

Field level each and every attribute of a bean class need to get validated against null/not null, empty/not empty, with min/max value to a specific value, valid email, and valid creditcard, etc., For each and everything, we have specific annotations. They are available for both server and client application programming. 

Few Annotations :

• @NotNull -> The field should not be null
• @NotEmpty -> The field should not be empty
• @Min(value = 2)-> The field value should have the min value as 2
• @Max(value = 5) -> The field maximum allowed value is 5
• @Email -> validates for a proper email

In this article let us see how to validate the data by using Hibernate validator. For that let us take a sample Maven Project containing a bean (model) class of a geekuser containing different attributes. We will see Hibernate Validator first before moving to the project.

Example Project

Project Structure:

 

As it is the maven project, all the dependencies are in

pom.xml

Below two are mandatory dependencies that are required to use the annotations that got used in the code.

<dependency>
  <groupId>org.hibernate</groupId>
  <artifactId>hibernate-validator</artifactId>
  <version>6.0.11.Final</version>
</dependency>

<!-- Verify validation annotations usage at compile time -->
<dependency>
  <groupId>org.hibernate</groupId>
  <artifactId>hibernate-validator-annotation-processor</artifactId>
  <version>6.0.11.Final</version>
</dependency>

While defining the bean class itself, we have to annotate according to our requirements

GeekUser.java

@NotNull(message = "Invalid Id. Please enter your Id")
private Long geekUserId;

@Size(max = 20, min = 3, message = "Invalid Name, Size should be between 3 to 20")

@NotEmpty(message = "Please enter your name")
private String geekUserName;

@Email(message = "Invalid EmailId.Please enter proper EmailId")

@NotEmpty(message = "Please enter your EmailId")
private String geekUserEmailId;

@Digits(integer = 3, fraction = 3, message = "Invalid age, Maximum valid number for age is 3 digits")
private int geekAge;

@Max(value = 5, message = "Invalid currentTimeOfWritingArticles, Maximum allowed is 5")
private String currentTimeOfWritingArticles;

@Min(value = 3, message = "Invalid allowedArticles, Minimum should be 3")
private String allowedForArticleReviewing;

@NotBlank(message = "Invalid Proficiency 3, Proficiency 3 Should not be blank")
private String proficiency3;

@Null(message = "Invalid Proficiency 4, Proficiency 4 should be null")
private String proficiency4;

@Pattern(regexp = "YN", flags = {
  Flag.CASE_INSENSITIVE }, message = "Invalid Proficiency 5, Enter text not matches with the standards")
  private String proficiency5;

@Positive(message = "Invalid Rating, Value should be positive")
private int rating;

@NegativeOrZero(message = "Invalid value for blocklisted, Input Number should be negative or Zero")
private int blocklisted;

@Future(message = "Invalid date, It should be provided as future date")
private Date futureDate;

@FutureOrPresent(message = "Invalid date, It should be as future or present date")
private Date futureOrPresent;

@PastOrPresent(message = "Invalid date, It should be as Past or present date")
private Date pastOrPresent;

@Range(min = 1, max = 3, message = "Invalid Range is given, Range should be within 1 to 3")
private int rangeExample;

@URL(message = "Invalid Url, Please provide a valid URL")
private String urlExample;

@CreditCardNumber(message = "Invalid Creditcard, It should not contain invalid character")
private String creditCardExample;

While giving the annotations, provide the message correctly which will be given as an error message if there is a violation happens with the given annotation. Now let us see the testing file that contains both the valid and invalid user. Need to write the code to print the error messages in case of errors. A lot of attributes need to be validated, and as a group, they are tested.

ValidatorExample.java

On execution of the above code, we see the below output in the console

 

So error messages help us to identify what is wrong and we can correct it appropriately. At the same time, if a few inputs are correct and a few are wrong, then the relevant error messages are seen. If all are correct,

 

So, by using these validation mechanisms, nicely we can validate data even for URLs, and Creditcard also. Annotations are user-friendly and according to our user requirements, they need to be applied and get the appropriate flow. This is an efficient way of validating the form data as well. Hibernate provides the facility effectively.