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 Details

    • 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