MACROMEDIA FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 Manual de usuario descargar pdf (Pagina 115)

Using function listeners 115

To find the appropriate static constant for your event type, see the events section of the

control’s entry in Adobe Flex 2 Language Reference.

Using function listeners

When migrating, convert all object event listeners to function event listeners. You can no

longer pass an object as the second parameter to the

addEventListener() method. The

listener argument of the

addEventListener() method was of type Object, which also

accepted a Function, but is now of type Function. If you try to pass an object listener, Flex

reports an error.

For example, if you had the following:

<?xml version="1.0"?>

<mx:Application xmlns:mx="http://www.macromedia.com/2003/mxml"

creationComplete="createHandler()">

<mx:Script>

import mx.core.Alert;

function createHandler() {

var myListener = new Object();

myListener.click = function(event) {

Alert.show("This is a log message");

}

myButton.addEventListener("click", myListener);

trace("Added listener");

}

</mx:Script>

<mx:Button label="Click Me" id="myButton"/>

</mx:Application>

Convert it to the following:

<?xml version="1.0"?>

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"

creationComplete="createHandler()">

<mx:Script>

import mx.controls.Alert;

private function createHandler():void {

trace("Added listener");

button1.addEventListener(MouseEvent.CLICK, myClickHandler);

}

private function myClickHandler(event:MouseEvent):void {

Alert.show("This is a log message");

}

</mx:Script>

<mx:Button label="Click Me" id="button1"/>

</mx:Application>

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