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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