Adobe FLEX 2 - CREATING AND EXTENDING COMPONENTS Manual page 220

This validator extends the Validator base class, as the following example shows:
package myValidators
{
import mx.validators.Validator;
import mx.validators.ValidationResult;
public class AgeValidator extends Validator {
// Define Array for the return value of doValidation().
private var results:Array;
// Constructor.
public function AgeValidator() {
// Call base class constructor.
super();
}
// Define the doValidation() method.
override protected function doValidation(value:Object):Array {
// Convert value to a Number.
var inputValue:Number = Number(value);
// Clear results Array.
results = [];
// Call base class doValidation().
results = super.doValidation(value);
// Return if there are errors.
if (results.length > 0)
return results;
// Create a variable and initialize it to the current date.
var currentYear:Date = new Date();
// If input value is not a number, or contains no value,
// issue a validation error.
if (isNaN(inputValue) || !value )
{
results.push(new ValidationResult(true, null, "NaN",
return results;
}
// If calculated age is less than 18, issue a validation error.
if ((currentYear.getFullYear() - inputValue) < 18) {
results.push(new ValidationResult(true, null, "tooYoung",
return results;
220 Creating Custom Validators
"You must enter a year."));
"You must be 18."));