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A form of multiple inheritance

In ActionScript, a class can inherit from (extend) only one other class. However, a class can inherit from (implement) any number of interfaces. Furthermore, each interface can extend any number of otherinterfaces.

Therefore, an ActionScript class can inherit any number of concrete methods from one superclass and can inherit any number of abstract methods from any number of interfaces.

Concrete methods are required

Any class that inherits an abstract method must provide a concrete definition for the method or the class cannot be compiled.

ActionScript classes cannot be declared abstract. Therefore, the abstract method cannot be passed down the class hierarchy for definition by asubclass as is the case in Java. The concrete version must be defined in the class in which it is inherited. This means that it must be defined inthe class that implements the interface.

What is a concrete method?

As a minimum, a concrete method is a method signature followed by a pair of matching curly braces (possibly containing a return statement) . Normally the body of the method is coded between the curly braces defining thebehavior of the method.

If the return type is void, the matching curly braces may be empty. In that case, the concrete method exhibits no observable behavior. It returnsimmediately without doing anything when it is called.

If the return type is not void, there must be a return statement that returns a value of the correct type.

Do empty methods have any value?

It is not uncommon for a class to implement an interface for which some of the interface methods are of no interest with regard to an object of the newclass. However, the implementing class must provide concrete definitions for all of the methods inherited from the interface.

In that case, it is common practice to simply define the uninteresting methods as empty methods in the new class. If they ever do get called,they will simply return immediately without doing anything.


The program named Interface01 that I will explain in this lesson is an update of the program named Polymorph02 that I explained in the earlier lesson titled "Polymorphism - The Big Picture" (see Baldwin's ActionScript programming website ).

The earlier program illustrated runtime polymorphism based on class inheritance and the overriding of inherited concrete methods.

This program will illustrate runtime polymorphism based on interface inheritance and the concrete definition of inherited abstract methods.

The project file structure

The project file structure is shown in Figure 1.

Project file structure.

Missing image
Project file structure.

Six ActionScript files

This project consists of one MXML file named Interface01 , three class files, and three interface files. The class files are named:

  • MyRectangle.as
  • MyCircle.as
  • Driver.as

The interface files are named:

  • IVolume.as
  • ICircumference.as
  • IArea.as

Interface can declare any number of methods

An interface can declare any number of methods including setter and getter methods. As you will see later, the interface named IArea declares two methods named area and id .

Questions & Answers

how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
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 ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
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.
Do you know which machine is used to that process?
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
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Object-oriented programming (oop) with actionscript. OpenStax CNX. Jun 04, 2010 Download for free at http://cnx.org/content/col11202/1.19
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