Sometimes I am asked to interview potential Flex programmers for clients. A common requirement is to assess the candidate's ability to design and develop custom components. Today's blog posting is dedicated to the hiring manager who called after regular business hours today.

The following code consists of several files. You will find seven questions embedded in the files. The questions should be answered in sequence, without looking ahead at the next file. All of these files compile and run without throwing errors. The first file does not contain any questions.

HireTest.mxml

<?xml version="1.0" encoding="utf-8"?>
<mx:Application 
    xmlns:tests="*"
    xmlns:mx="http://www.adobe.com/2006/mxml">
    <tests:MeasureTest1 />
    <tests:CreateChildren1 />
    <tests:DisplayList1 />
    <tests:Sequence1 />
</mx:Application>

MeasureTest1.mxml

<?xml version="1.0" encoding="utf-8"?>
<mx:Canvas 
    height="300" 
    width="400" 
    xmlns:mx="http://www.adobe.com/2006/mxml">
    <mx:Script>
        <![CDATA[
            // 1) what does measure() do? 
            override protected function measure():void { 
                // 2) Why is this method never called?
            }
        ]]>
    </mx:Script>
    <mx:Label text="Hello from MeasureTest1" />
</mx:Canvas>

CreateChildren1.mxml

<?xml version="1.0" encoding="utf-8"?>
<mx:Canvas 
    height="300" 
    width="400" 
    xmlns:mx="http://www.adobe.com/2006/mxml">
    <mx:Script>
        <![CDATA[
            // 3) what does createChildren() do? 
            override protected function createChildren():void { 
                // 4) Why doesn't the Label (below) display?
            }
        ]]>
    </mx:Script>
    <mx:Label text="Hello from CreateChildren1" />
</mx:Canvas>

DisplayList1.mxml

<?xml version="1.0" encoding="utf-8"?>
<mx:Canvas 
    height="300" 
    width="400" 
    xmlns:mx="http://www.adobe.com/2006/mxml">
    <mx:Script>
        <![CDATA[
            // 5) what does updateDisplayList() do? 
            override protected function updateDisplayList(w:Number, h:Number):void { 
                // 6) Why doesn't the Label (below) display?
            }
        ]]>
    </mx:Script>
    <mx:Label text="Hello from UpdateDisplayList1" />
</mx:Canvas>

Sequence1.mxml

<?xml version="1.0" encoding="utf-8"?>
   <mx:Canvas 
   height="400" 
   width="100%"
   xmlns:mx="http://www.adobe.com/2006/mxml">
   <mx:Script>
   <![CDATA[
   // 7) What will be displayed in textArea? 
   
   override protected function commitProperties():void {
     super.commitProperties();
     textArea.text += "commitProperties\n";
   }
   
   override protected function createChildren():void { 
     super.createChildren();
     textArea.text += "createChildren\n";
   }

   override protected function layoutChrome(w:Number, h:Number):void {
     super.layoutChrome(w, h);
     textArea.text += "layoutChrome\n";
   }
   
   override protected function measure():void { 
     super.measure();
     textArea.text += "measure\n";
     invalidateSize();
   }
   
   override protected function updateDisplayList(w:Number, h:Number):void { 
     super.updateDisplayList(w, h);
     textArea.text += "updateDisplayList\n";
     invalidateProperties();
   }
   ]]>
   </mx:Script>
   <mx:TextArea height="200" id="textArea" text="" width="100%" />
 </mx:Canvas>

What are your favorite skill-testing questions for Flex programmers?

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Read more from Mike Slinn.