<?xml version="1.0"?>
  <!-- Simple example to demonstrate the Validator class. -->
  <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">
  
      <mx:Script>
          <![CDATA[
  
                          // Import necessary classes.
              import mx.controls.Alert;
                          import mx.events.ValidationResultEvent;
                          
                          // Event listener for the valid and invalid events.
                          private function handleValid(eventObj:ValidationResultEvent):void {
                                  if(eventObj.type==ValidationResultEvent.VALID)        
                                      // Enable Submit button.
                                          submitButton.enabled = true;
                                  else
                                          submitButton.enabled = false;
                          }
  
                          // Submit form is everything is valid. 
                          private function submitForm():void {
                                  Alert.show("Form Submitted!");
                          }
  
          ]]>
      </mx:Script>
  
      <!-- The Validator class defines the required property and the validator events
           used by all validator subclasses. -->
      <mx:Validator id="reqValid" required="true"
          source="{fname}" property="text" 
          valid="handleValid(event)" invalid="handleValid(event)"/>
          
      <mx:Panel title="Validator Example" width="100%" height="100%" 
              paddingTop="5" paddingLeft="5" paddingRight="5" paddingBottom="5">
  
          <mx:Form>
              <mx:Text width="100%" color="blue"
                  text="Enter a value in the Name field before you can submit. The E-mail field is optional."/>
  
              <mx:FormItem label="Name: " required="true">
                  <mx:TextInput id="fname" width="100%"/>
              </mx:FormItem>
  
              <mx:FormItem label="E-mail address: " required="false">
                  <mx:TextInput id="email" width="100%"/>
              </mx:FormItem>
              
              <mx:FormItem>
                  <mx:Button id="submitButton" enabled="false" 
                      label="Submit" click="submitForm();"/>
              </mx:FormItem>
          </mx:Form>
  
      </mx:Panel>
  </mx:Application>