Flex - DropDownList Control


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Introduction

The DropDownList control contains a drop-down list from which the user can select a single value similar to that of the SELECT form element in HTML.

Class Declaration

Following is the declaration for spark.components.DropDownList class −

public class DropDownList 
   extends DropDownListBase 

Public Properties

S.No Property & Description
1

prompt : String

The prompt for the DropDownList control.

2

typicalItem : Object

[override] Layouts use the preferred size of the typicalItem when fixed row or column sizes are required, but a specific rowHeight or columnWidth value is not set.

Public Methods

S.No Method & Description
1

DropDownList()

Constructor.

Methods Inherited

This class inherits methods from the following classes −

  • spark.components.supportClasses.DropDownListBase
  • spark.components.List
  • spark.components.supportClasses.ListBase
  • spark.components.SkinnableDataContainer
  • spark.components.supportClasses.SkinnableContainerBase
  • spark.components.supportClasses.SkinnableComponent
  • mx.core.UIComponent
  • mx.core.FlexSprite
  • flash.display.Sprite
  • flash.display.DisplayObjectContainer
  • flash.display.InteractiveObject
  • flash.display.DisplayObject
  • flash.events.EventDispatcher
  • Object

Flex DropDownList Control Example

Let us follow the following steps to check usage of DropDownList control in a Flex application by creating a test application −

Step Description
1 Create a project with a name HelloWorld under a package com.tutorialspoint.client as explained in the Flex - Create Application chapter.
2 Modify HelloWorld.mxml as explained below. Keep rest of the files unchanged.
3 Compile and run the application to make sure business logic is working as per the requirements.

Following is the content of the modified mxml file src/com.tutorialspoint/HelloWorld.mxml.

<?xml version = "1.0" encoding = "utf-8"?>
<s:Application xmlns:fx = "http://ns.adobe.com/mxml/2009"
   xmlns:s = "library://ns.adobe.com/flex/spark"
   xmlns:mx = "library://ns.adobe.com/flex/mx"
   width = "100%" height = "100%" minWidth = "500" minHeight = "500">

   <fx:Style source = "/com/tutorialspoint/client/Style.css" />
   <fx:Script>
      <![CDATA[
         import mx.collections.ArrayCollection; 
         import spark.events.IndexChangeEvent;
		 
         [Bindable]
         public var data:ArrayCollection = new ArrayCollection (
         [   
            {value:"France", code:"FR"},
            {value:"Japan", code:"JP"},
            {value:"India", code:"IN"},
            {value:"Russia", code:"RS"},
            {value:"United States", code:"US"}		
         ]                
         );

         protected function dropDownList_changeHandler
           (event:IndexChangeEvent):void {
            ddlIndex.text = dropDownList.selectedIndex.toString();
            ddlSelectedItem.text = dropDownList.selectedItem.value;
            ddlCode.text = dropDownList.selectedItem.code;
         }

      ]]>
   </fx:Script>

   <s:BorderContainer width = "550" height = "400" id = "mainContainer"
      styleName = "container">
      <s:VGroup width = "100%" height = "100%" gap = "50" horizontalAlign = "center"
         verticalAlign = "middle">
         <s:Label id = "lblHeader" text = "Form Controls Demonstration" 
            fontSize = "40" color = "0x777777" styleName = "heading" />
         
         <s:Panel id = "dropDownListPanel" title = "Using DropDownList" 
            width = "420" height = "200">
            <s:layout>
               <s:VerticalLayout  gap = "10" verticalAlign = "middle" 
                  horizontalAlign = "center" />	
            </s:layout>
            
            <s:HGroup>
               <s:Label text = "Index :" />
               <s:Label id = "ddlIndex" fontWeight = "bold" />
               <s:Label text = "Value :" /> 
               <s:Label id = "ddlSelectedItem" 
                  text = "{dropDownList.selectedItem.value}" fontWeight = "bold" />
               <s:Label text = "Code :" /> 
               <s:Label id = "ddlCode" 
                  text = "{dropDownList.selectedItem.code}" fontWeight = "bold" />
            </s:HGroup>				
            
            <s:DropDownList id = "dropDownList" dataProvider = "{data}" 
               width = "150" change = "dropDownList_changeHandler(event)"
               selectedIndex = "0" labelField = "value" />     				
         </s:Panel>
      </s:VGroup>	 
   </s:BorderContainer>	
</s:Application>

Once you are ready with all the changes done, let us compile and run the application in normal mode as we did in Flex - Create Application chapter. If everything is fine with your application, it will produce the following result: [ Try it online ]

Flex DropDownList Control
flex_form_controls.htm

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