The following example shows how you can set a prompt on a Flex ComboBox control by setting the prompt property.
Full code after the jump.
You can reset a ComboBox control so that its prompt message is visible again by setting the selectedIndex property to -1.
<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/06/01/setting-a-prompt-on-a-combobox-control-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
layout="vertical"
verticalAlign="top"
backgroundColor="white">
<mx:Array id="arr">
<mx:Object abbrev="AL" name="Alabama" />
<mx:Object abbrev="AK" name="Alaska" />
<mx:Object abbrev="AZ" name="Arizona" />
<mx:Object abbrev="AR" name="Arkansas" />
<mx:Object abbrev="CA" name="California" />
<mx:Object abbrev="CO" name="Colorado" />
<mx:Object abbrev="CT" name="Connecticut" />
</mx:Array>
<mx:ApplicationControlBar dock="true">
<mx:Button id="button"
label="Reset ComboBox"
click="comboBox.selectedIndex = -1;" />
</mx:ApplicationControlBar>
<mx:ComboBox id="comboBox"
dataProvider="{arr}"
labelField="name"
prompt="Please select a state..." />
</mx:Application>
View source is enabled in the following example.
Due to popular demand, here is the “same” example in a more ActionScript friendly format:
<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/06/01/setting-a-prompt-on-a-combobox-control-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
layout="vertical"
verticalAlign="top"
backgroundColor="white"
initialize="init();">
<mx:Script>
<![CDATA[
import mx.controls.ComboBox;
import mx.controls.Button;
import mx.containers.ApplicationControlBar;
private var arr:Array;
private var appControlBar:ApplicationControlBar;
private var button:Button;
private var comboBox:ComboBox;
private function init():void {
arr = [];
arr.push({abbrev:"AL", name:"Alabama"});
arr.push({abbrev:"AK", name:"Alaska"});
arr.push({abbrev:"AZ", name:"Arizona"});
arr.push({abbrev:"AR", name:"Arkansas"});
arr.push({abbrev:"CA", name:"California"});
arr.push({abbrev:"CO", name:"Colorado"});
arr.push({abbrev:"CT", name:"Connecticut"});
button = new Button();
button.label = "Reset ComboBox";
button.addEventListener(MouseEvent.CLICK, button_click);
appControlBar = new ApplicationControlBar();
appControlBar.dock = true;
appControlBar.addChild(button);
Application.application.addChildAt(appControlBar, 0);
comboBox = new ComboBox();
comboBox.dataProvider = arr;
comboBox.labelField = "name";
comboBox.prompt = "Please select a state...";
addChild(comboBox);
}
private function button_click(evt:MouseEvent):void {
comboBox.selectedIndex = -1;
}
]]>
</mx:Script>
</mx:Application>




wow, this blog is so great, thank you very much….
Thank you :-)
this is of great help….can you also mention how to control 3d zoom using as3.
thanks
I am trying to figure out how to run my jsp files through a flex application. Can someone help me with this?
Scott,
There are several examples of using Flex and JSP at http://learn.adobe.com/wiki/display/Flex/Getting+Started. You can use the search box in the top right corner to find several code snippets.
Peter
Thanks for this one. It’s helped me out