Hibernate-validator: Hello World application

In this post, I am going to show you an example of bean validation API annotations @Min, @Size.

JSR 380 specification provides @Min, @Size annotation to validate the bean properties.

Below table summarizes these annotations.

Annotation	Description
@Min	If you annotate any number field with this annotation, then the element must be greater than or equal to the specified minimum value.
@Size	The annotated element size must be within given boundaries.

public class Employee {

 @Min(value=1)
 private int id;
 
 @Size(min=5, max=30)
 private String firstName;
 
 @Size(min=5, max=30)
 private String lastName;
 
 .....
 .....

}

For example,

@Min(value=1)

private int id;

I annotated id with @Min(value=1), this annotation make sure that the value of the id is >=1, else it generated validation error.

@Size(min=5, max=30)

private String firstName;

I annotated firstName with @Size(min=5, max=30), this annotation make sure that the length of the field firstName is minimum 5 character and maximum 30 character.

Find the below working application.

Employee.java

package com.sample.model;

import javax.validation.constraints.Min;
import javax.validation.constraints.Size;

public class Employee {

 @Min(value=1)
 private int id;
 
 @Size(min=5, max=30)
 private String firstName;
 
 @Size(min=5, max=30)
 private String lastName;
 
 public Employee(int id, String firstName, String lastName) {
  this.id = id;
  this.firstName = firstName;
  this.lastName = lastName;
 }

 public int getId() {
  return id;
 }

 public void setId(int id) {
  this.id = id;
 }

 public String getFirstName() {
  return firstName;
 }

 public void setFirstName(String firstName) {
  this.firstName = firstName;
 }

 public String getLastName() {
  return lastName;
 }

 public void setLastName(String lastName) {
  this.lastName = lastName;
 }

}

Test.java

package com.sample.test;

import java.util.Set;

import javax.validation.*;
import javax.validation.ValidatorFactory;

import com.sample.model.Employee;

public class Test {
 public static void main(String args[]) {
  ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();
  Validator validator = validatorFactory.getValidator();

  Employee emp = new Employee(-1, "Hareesh", "Ram");

  Set<ConstraintViolation<Employee>> validationErrors = validator.validate(emp);

  for (ConstraintViolation<Employee> violation : validationErrors) {
   System.out.println(violation.getPropertyPath() + "," + violation.getMessage());
  }
 }
}

When I ran above application, I seen below messages in the console.

id,must be greater than or equal to 1

lastName,size must be between 5 and 30

Since the fields id, firstName are violating the minimum requirements specified by using @Id, @Size annotations, validator generates these error messages.

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