The following example(s) require Flash Player 10 and the Adobe Flex 4 SDK. To download the Adobe Flash Builder 4 trial, see http://www.adobe.com/products/flex/. To download the latest nightly build of the Flex 4 SDK, see http://opensource.adobe.com/wiki/display/flexsdk/Download+Flex+4.
For more information on getting started with Flex 4 and Flash Builder 4, see the official Adobe Flex Team blog.

<?xml version="1.0" encoding="utf-8"?> 
<!-- http://blog.flexexamples.com/2010/03/12/checking-that-an-item-is-selected-in-the-spark-dropdownlist-control-in-flex-4/ -->
<s:Application name="Spark_DropDownList_requiresSelection_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009" 
        xmlns:s="library://ns.adobe.com/flex/spark" 
        xmlns:mx="library://ns.adobe.com/flex/mx"> 
    <s:layout>
        <s:HorizontalLayout horizontalAlign="center" verticalAlign="middle" />
    </s:layout>
 
    <s:DropDownList id="ddl" prompt="Please select an item" requireSelection="true">
        <s:dataProvider>
            <s:ArrayList source="[one,two,three,four,five,six,seven]" />
        </s:dataProvider>
    </s:DropDownList>
 
</s:Application>

View source is enabled in the following example.

Or you can use a NumberValidator on the Spark DropDownList control to check that the selectedIndex property is greater than or equal to 0, as seen in the following example:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/03/12/checking-that-an-item-is-selected-in-the-spark-dropdownlist-control-in-flex-4/ -->
<s:Application name="Spark_DropDownList_selectedIndex_NumberValidator_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009" 
        xmlns:s="library://ns.adobe.com/flex/spark" 
        xmlns:mx="library://ns.adobe.com/flex/mx"> 
    <s:layout>
        <s:HorizontalLayout horizontalAlign="center" verticalAlign="middle" />
    </s:layout>
 
    <fx:Script>
        <![CDATA[
            import mx.controls.Alert;
            import mx.events.ValidationResultEvent;
 
            protected function button1_clickHandler(evt:MouseEvent):void {
                numValidator.validate();
            }
 
            protected function numValidator_validHandler(evt:ValidationResultEvent):void {
                Alert.show("DropDownList item selected: " + ddl.selectedItem.toString(), evt.type);
            }
 
            protected function numValidator_invalidHandler(evt:ValidationResultEvent):void {
                Alert.show(ddl.prompt, evt.type);
            }
        ]]>
    </fx:Script>
 
    <fx:Declarations>
        <mx:NumberValidator id="numValidator"
                source="{ddl}"
                property="selectedIndex"
                minValue="0"
                lowerThanMinError="{ddl.prompt}"
                valid="numValidator_validHandler(event);"
                invalid="numValidator_invalidHandler(event);" />
    </fx:Declarations>
 
    <s:DropDownList id="ddl" prompt="Please select an item">
        <s:dataProvider>
            <s:ArrayList source="[one,two,three,four,five,six,seven]" />
        </s:dataProvider>
    </s:DropDownList>
 
    <s:Button label="validate" click="button1_clickHandler(event);" />
 
</s:Application>

View source is enabled in the following example.

This entry is based on a beta version of the Flex 4 SDK and therefore is very likely to change as development of the Flex SDK continues. The API can (and will) change causing examples to possibly not compile in newer versions of the Flex 4 SDK.

 

Full code after the jump.

The following example(s) require Flash Player 10 and the Adobe Flex 4 SDK. To download the Adobe Flash Builder 4 trial, see http://www.adobe.com/products/flex/. To download the latest nightly build of the Flex 4 SDK, see http://opensource.adobe.com/wiki/display/flexsdk/Download+Flex+4.
For more information on getting started with Flex 4 and Flash Builder 4, see the official Adobe Flex Team blog.

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2009/02/21/setting-the-selected-index-on-the-fxbuttonbar-control-in-flex-gumbo/ -->
<s:Application name="Spark_ButtonBar_selectedIndex_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark"
        xmlns:mx="library://ns.adobe.com/flex/mx">
    <s:controlBarContent>
        <mx:Form>
            <mx:FormItem label="requiresSelection:">
                <s:CheckBox id="checkBox" />
            </mx:FormItem>
            <mx:FormItem label="selectedIndex:"
                         direction="horizontal">
                <s:HSlider id="slider"
                           minimum="-1"
                           maximum="5" />
                <s:Label text="{btnBar.selectedIndex}" />
            </mx:FormItem>
        </mx:Form>
    </s:controlBarContent>
 
    <s:ButtonBar id="btnBar"
                 selectedIndex="@{slider.value}"
                 requireSelection="{checkBox.selected}"
                 horizontalCenter="0" verticalCenter="0">
        <s:dataProvider>
            <s:ArrayList source="[One,Two,Three,Four,Five,Six]" />
        </s:dataProvider>
    </s:ButtonBar>
 
</s:Application>

This entry is based on a beta version of the Flex 4 SDK and therefore is very likely to change as development of the Flex SDK continues. The API can (and will) change causing examples to possibly not compile in newer versions of the Flex 4 SDK.

 

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.

View MXML

<?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:

View MXML

<?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>

 

Full code after the jump.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/01/20/setting-the-selected-index-of-a-flex-linkbar-control/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Array id="arr">
        <mx:Object label="One" />
        <mx:Object label="Two" />
        <mx:Object label="Three" />
        <mx:Object label="Four" />
    </mx:Array>

    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="selectedIndex:">
                <mx:HSlider id="slider"
                        minimum="0"
                        maximum="{linkBar.dataProvider.length - 1}"
                        liveDragging="true"
                        snapInterval="1"
                        tickInterval="1"
                        dataTipPrecision="0" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:LinkBar id="linkBar"
            dataProvider="{arr}"
            selectedIndex="{slider.value}" />

</mx:Application>

View source is enabled in the following example.

You can also set the selectedIndex property in ActionScript, as shown in the following snippet:

<mx:Script>
    <![CDATA[
        import mx.events.SliderEvent;

        private function slider_change(evt:SliderEvent):void {
            linkBar.selectedIndex = evt.value;
        }
    ]]>
</mx:Script>

 

Full code after the jump.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/01/04/using-a-timer-to-change-the-selected-index-of-a-viewstack-container-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white"
        creationComplete="init();">

    <mx:Script>
        <![CDATA[
            private var timer:Timer;

            private function init():void {
                timer = new Timer(1000); /* 1000ms == 1second */
                timer.addEventListener(TimerEvent.TIMER, onTimer);
            }

            private function onTimer(evt:TimerEvent):void {
                var idx:uint = viewStack.selectedIndex;
                var max:uint = viewStack.numChildren;

                var newIdx:uint = ++idx % max;
                viewStack.selectedIndex = newIdx;
            }

            private function startTimer():void {
                if (!timer.running) {
                    timer.start();
                }
            }

            private function stopTimer():void {
                if (timer.running) {
                    timer.stop();
                }
            }
        ]]>
    </mx:Script>

    <mx:ApplicationControlBar dock="true">
        <mx:Button label="Start timer" click="startTimer();" />
        <mx:Button label="Stop timer" click="stopTimer();" />

        <mx:Spacer width="100%" />

        <mx:Label text="selectedIndex:" />
        <mx:HSlider id="slider"
                minimum="0"
                maximum="3"
                liveDragging="true"
                snapInterval="1"
                tickInterval="1"
                change="viewStack.selectedIndex = event.value;" />
    </mx:ApplicationControlBar>

    <mx:ViewStack id="viewStack" width="100%" height="100%">
        <mx:VBox backgroundColor="haloBlue"
                width="100%"
                height="100%">
            <mx:Label text="VBox 1" />
        </mx:VBox>
        <mx:VBox backgroundColor="haloGreen"
                width="100%"
                height="100%">
            <mx:Label text="VBox 2" />
        </mx:VBox>
        <mx:VBox backgroundColor="haloOrange"
                width="100%"
                height="100%">
            <mx:Label text="VBox 3" />
        </mx:VBox>
        <mx:VBox backgroundColor="haloSilver"
                width="100%"
                height="100%">
            <mx:Label text="VBox 4" />
        </mx:VBox>
    </mx:ViewStack>

</mx:Application>

View source is enabled in the following example.

 

Full code after the jump.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/09/17/programmatically-changing-a-flex-accordion-containers-selected-index/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white"
        creationComplete="init();">

    <mx:Script>
        <![CDATA[
            private function init():void {
                slider.maximum = accordion.numChildren -1;
                slider.labels = [0, slider.maximum];
            }

            private function dataTipFunc(item:Object):String {
                return "selectedIndex = " + item.toString();
            }
        ]]>
    </mx:Script>

    <mx:ApplicationControlBar dock="true">
        <mx:Label text="selectedIndex:" />
        <mx:HSlider id="slider"
                minimum="0"
                liveDragging="true"
                snapInterval="1"
                tickInterval="1"
                change="accordion.selectedIndex = event.value;"
                dataTipFormatFunction="dataTipFunc"
                dataTipPlacement="bottom" />
    </mx:ApplicationControlBar>

    <mx:Accordion id="accordion"
            historyManagementEnabled="false"
            width="100%"
            height="100%"
            change="slider.value = event.newIndex;">
        <mx:VBox label="One" />
        <mx:VBox label="Two" />
        <mx:VBox label="Three" />
        <mx:VBox label="Four" />
        <mx:VBox label="Five" />
    </mx:Accordion>

</mx:Application>

View source is enabled in the following example.

 

Full code after the jump.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/08/27/adding-icons-to-a-flex-accordion-control/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Script>
        <![CDATA[
            [Bindable]
            [Embed(source="assets/bulletCheck.png")]
            private var BulletCheck:Class;

            [Bindable]
            [Embed(source="assets/bulletWarning.png")]
            private var BulletWarning:Class;

            [Bindable]
            [Embed(source="assets/bulletCritical.png")]
            private var BulletCritical:Class;
        ]]>
    </mx:Script>

    <mx:XML id="itemsXML">
        <items>
            <item label="Item 1" status="warning" />
            <item label="Item 2" status="critical" />
            <item label="Item 3" status="critical" />
            <item label="Item 4" status="check" />
            <item label="Item 5" status="warning" />
            <item label="Item 6" status="check" />
            <item label="Item 7" status="check" />
            <item label="Item 8" status="critical" />
        </items>
    </mx:XML>

    <mx:ApplicationControlBar dock="true">
        <mx:Label text="selectedIndex: {accordion.selectedIndex}" />
        <mx:Spacer width="100" />
        <mx:Label text="label: {accordion.getHeaderAt(accordion.selectedIndex).label}" />
    </mx:ApplicationControlBar>

    <mx:Accordion id="accordion"
            width="400"
            height="200">
        <mx:VBox label="Success"
                icon="{BulletCheck}"
                width="100%"
                height="100%">
            <mx:DataGrid id="successGrid"
                    dataProvider="{itemsXML.item.(@status == 'check')}"
                    width="100%"
                    height="100%">
            </mx:DataGrid>
        </mx:VBox>

        <mx:VBox label="Warning"
                icon="{BulletWarning}"
                width="100%"
                height="100%">
            <mx:DataGrid id="warningGrid"
                    dataProvider="{itemsXML.item.(@status == 'warning')}"
                    width="100%"
                    height="100%">
            </mx:DataGrid>
        </mx:VBox>

        <mx:VBox label="Critical"
                icon="{BulletCritical}"
                width="100%"
                height="100%">
            <mx:DataGrid id="criticalGrid"
                    dataProvider="{itemsXML.item.(@status == 'critical')}"
                    width="100%"
                    height="100%">
            </mx:DataGrid>
        </mx:VBox>
    </mx:Accordion>

</mx:Application>

View source is enabled in the following example.