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Polymorphism kicks in

The compiler can't possibly know which type of object will be instantiated as a result of the random process following each button click when the program iscompiled. Therefore, the decision as to which set of methods to call as a result of each button click cannot be determined until runtime. This isthe essence of runtime polymorphism .

The cardinal rule

The type of the object's reference determines which set of method names canbe called on that reference. In this case, the set consists of the four methods declared in and inherited into the interface named IArea , which are shown in the above list .

The type of the object determines which method from the set of allowable names is actually executed.

Run the program

You can run the program to see the outputs produced by repeatedly clicking each of the three buttons inFigure 2.

Discussion and sample code

Will discuss in fragments

I will break the longer files in this application down and discuss them in fragments. Complete listings of all of the files areprovided in Listing 10 through Listing 16 near the end of the lesson.

The file named Interface01.mxml

In keeping with my plan to emphasize ActionScript over Flex in this series of lessons, the MXML file for this application is very simple, instantiating only asingle object of type Driver . A listing of the MXML file is provided in Listing 10 near the end of the lesson.

The file named Driver.as

The class named Driver begins in Listing 1. A complete listing of the file is provided in Listing 11 near the end of the lesson.

Beginning of the class named driver.

package CustomClasses{ import flash.events.*;import mx.containers.HBox;import mx.containers.VBox; import mx.controls.Button;import mx.controls.Label; import mx.controls.TextArea;public class Driver extends VBox{private var textArea:TextArea = new TextArea(); private var myShape:IArea;private var randomChoice:Number;private var radius:uint; private var rectWidth:uint;private var rectHeight:uint;

Listing 1 declares several new instance variables. The most interesting variable is named myShape because it is declared to be of type IArea , which is the name of an interface.

References to objects of the classes MyCircle and MyRectangle will be stored in this variable.

Beginning of the constructor for the Driver class

The constructor for the Driver class begins in Listing 2.

Beginning of the constructor for the driver class.

public function Driver(){//constructor var label:Label = new Label();label.text = "Interface Polymorphism Demo"; label.setStyle("fontSize",14);label.setStyle("color",0xFFFF00); addChild(label);//Put three buttons in an HBoxvar hbox:HBox = new HBox(); addChild(hbox);var areaButton:Button = new Button();areaButton.label = "Area"; hbox.addChild(areaButton);var circButton:Button = new Button();circButton.label = "Circumference"; hbox.addChild(circButton);var volumeButton:Button = new Button();volumeButton.label = "Volume"; hbox.addChild(volumeButton);//Put the text area below the HBox.textArea.width = 245; textArea.height = 80;addChild(textArea);

Questions & Answers

how do they get the third part x = (32)5/4
kinnecy Reply
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
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?
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
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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