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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

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
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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