Package jakarta.faces.validator

Interface Validator<T>

Type Parameters:

T - The generic type of object value to validate.

All Superinterfaces:

EventListener

All Known Implementing Classes:

BeanValidator, DoubleRangeValidator, LengthValidator, LongRangeValidator, MethodExpressionValidator, RegexValidator, RequiredValidator

public interface Validator<T>
extends EventListener

A Validator implementation is a class that can perform validation (correctness checks) on a EditableValueHolder. Zero or more Validators can be associated with each EditableValueHolder in the view, and are called during the Process Validations phase of the request processing lifecycle.

Individual Validators should examine the value and component that they are passed, and throw a ValidatorException containing a FacesMessage, documenting any failures to conform to the required rules.

For maximum generality, Validator instances may be configurable based on properties of the Validator implementation class. For example, a range check Validator might support configuration of the minimum and maximum values to be used.

Validator implementations must have a zero-arguments public constructor. In addition, if the Validator class wishes to have configuration property values saved and restored with the view, the implementation must also implement StateHolder.

If the class implementing Validator has a ResourceDependency annotation, the action described in ResourceDependency must be taken when EditableValueHolder.addValidator(jakarta.faces.validator.Validator) is called. If the class implementing Validator has a ResourceDependencies annotation, the action described in ResourceDependencies must be taken when EditableValueHolder.addValidator(jakarta.faces.validator.Validator) is called.

Method Summary

Modifier and Type	Method	Description
void	validate(FacesContext context, UIComponent component, T value)	Perform the correctness checks implemented by this Validator against the specified UIComponent.

Method Detail

validate

void validate(FacesContext context,
              UIComponent component,
              T value)
       throws ValidatorException

Perform the correctness checks implemented by this Validator against the specified UIComponent. If any violations are found, a ValidatorException will be thrown containing the FacesMessage describing the failure.

For a validator to be fully compliant with Version 2 and later of the specification, it must not fail validation on null or empty values unless it is specifically intended to address null or empty values. An application-wide <context-param> is provided to allow validators designed for Jakarta Faces 1.2 to work with Jakarta Faces 2 and later. The jakarta.faces.VALIDATE_EMPTY_FIELDS <context-param> must be set to false to enable this backwards compatibility behavior.

Parameters:

context - FacesContext for the request we are processing

component - UIComponent we are checking for correctness

value - the value to validate

Throws:

ValidatorException - if validation fails

NullPointerException - if context or component is null