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Beginning in the Fall 2010 semester, I will upgrade my Introduction to XML course to include both Flex 3 and Flex 4.

Flex is a cryptic shorthand programming language

The important thing to remember is that Flex (versions 3 and 4) is simply cryptic xml-based shorthand programming languages that can be used tocreate some aspects ActionScript programs. You should also remember that anything that can be programmed in Flex can be programmed directly inActionScript. However, the reverse is not true.

When Adobe released Flex 4 and Flash Builder 4, they actually added a large number of classes to the ActionScript application programming interface (API) . So, the real question is not whether you should use Flex 4. The real question is whether the new classes that were added to the API are useful inyour application. If so, use them. If not, stick with the classes that were part of the API before the new classes were added.

Understanding Flex

If you really want to understand Flex (instead of simply using it in cookbook fashion) you need to learn about object-oriented programming using ActionScript.

Viewing tip

I recommend that you open another copy of this document in a separate browser window and use the following links to easily find and view the figures andlistings while you are reading about them.


  • Figure 1 . Test program output for alpha values of 0.0, 0.33, 0.66, and 1.0.
  • Figure 2 . The FlashDevelop IDE at startup.
  • Figure 3 . The new project dialog.
  • Figure 4 . The FlashDevelop IDE for a new project named test.
  • Figure 5 . FlashDevelop text editor showing skeleton code for a Flex 3 project.
  • Figure 6 . Test program output displayed in the Flash Player.
  • Figure 7 . FlashDevelop showing the Debug/Release pull-down list.
  • Figure 8 . The New Flex Project dialog in Flash Builder 4.
  • Figure 9 . Contents of the project tree for the test program with Flash Builder 4.


  • Listing 1 . Flex application named test.mxml.

Supplemental material

I recommend that you also study the other lessons in my extensive collection of online programming tutorials. You will find a consolidated index at www.DickBaldwin.com .


You learned how to create a Flex project named AppBackground01 using Flex Builder 3 in the earlier lesson titled The Default Application Container - Flex 3 and Flex 4 . However, Flex Builder 3 is no longer available from the Adobe website.

Therefore, in this lesson, I will explain how to create the same Flex project in three different ways. However, in this lesson, I will shorten the name of theproject by changing the project name to test .

Discussion and sample code

Run the program

Before continuing, I suggest that you run the program to familiarize yourself with the screen output.

Different ways to create Flex 3 applications

Here is a list of four different ways that you can create Flex 3 applications:

  1. Use Flex Builder 3 if you already have it or can find it on the web.
  2. Download and use the free open-source Adobe Flex 3 SDK (see Resources ).
  3. Download and use the free FlashDevelop IDE ( see Resources )
  4. Download and use Flash Player 4 with the Flex 3 SDK ( see Resources )

Questions & Answers

what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Introduction to xml. OpenStax CNX. Dec 02, 2014 Download for free at https://legacy.cnx.org/content/col11207/1.18
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