Every constraint has a ‘message’ attribute, using this you can customize the validation error messages.
Example
@Size(min=5, message="Name must have atlease 5 characters")
private String name;
Find the below working application.
Employee.java
package com.sample.app.model;
import javax.validation.constraints.Size;
public class Employee {
private int id;
@Size(min=5, message="Name must have atlease 5 characters")
private String name;
public Employee(int id, String name) {
this.id = id;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
}
App.java
package com.sample.app;
import java.util.Set;
import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
import com.sample.app.model.Employee;
public class App {
private static ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();
private static Validator validator = validatorFactory.getValidator();
private static void validateBean(Employee emp) {
System.out.println("************************************");
Set<ConstraintViolation<Employee>> validationErrors = validator.validate(emp);
if (validationErrors.size() == 0) {
System.out.println("No validation errors....");
}
for (ConstraintViolation<Employee> violation : validationErrors) {
System.out.println(violation.getPropertyPath() + "," + violation.getMessage());
}
System.out.println("");
}
public static void main(String args[]) {
Employee emp1 = new Employee(1, "Ram");
System.out.println("Validation Errors for emp1");
validateBean(emp1);
Employee emp2 = new Employee(2, "RamaKrishna");
System.out.println("Validation Errors for emp2");
validateBean(emp2);
}
}
Run App.java, you will see below messages in console.
Validation Errors for emp1 ************************************ name,Name must have atlease 5 characters Validation Errors for emp2 ************************************ No validation errors....
You can use expression language to access the validated value.
Example
@Size(min=5, message="Name '${validatedValue}' is not upto the requirement. Name must have atleast 5 characters")
private String name;
${validatedValue}: It gets the validated value. Let’s update Employee class with the new message using expression language.
Employee.java
package com.sample.app.model;
import javax.validation.constraints.Size;
public class Employee {
private int id;
@Size(min=5, message="Name '${validatedValue}' is not upto the requirement. Name must have atleast 5 characters")
private String name;
public Employee(int id, String name) {
this.id = id;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
}
Run App.java, you will see below messages in console.
Validation Errors for emp1 ************************************ name,Name 'Ram' is not upto the requirement. Name must have atleast 5 characters Validation Errors for emp2 ************************************ No validation errors....
you can even include the constraint boundaries using Expression language.
For example, {min} is used to access the value of min attribute.
@Size(min=5, message="Name '${validatedValue}' is not upto the requirement. Name must have atleast {min} characters")
private String name;
Employee.java
package com.sample.app.model;
import javax.validation.constraints.Size;
public class Employee {
private int id;
@Size(min=5, message="Name '${validatedValue}' is not upto the requirement. Name must have atleast {min} characters")
private String name;
public Employee(int id, String name) {
this.id = id;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
}
Run App.java, you will see below messages in console.
Validation Errors for emp1 ************************************ name,Name 'Ram' is not upto the requirement. Name must have atleast 5 characters Validation Errors for emp2 ************************************ No validation errors....
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