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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

can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
im not good at math so would this help me
Rachael Reply
I'm not good at math so would you help me
what is the problem that i will help you to self with?
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris 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?
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
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
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele 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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