<< Chapter < Page Chapter >> Page >

Figure 2 . Text output for overridden ToString method and class B.

ToString in class B

Do you recognize this?

You should recognize this as the text that was encapsulated in the String object returned by the overridden version of the ToString method defined in the class named B . (See Listing 2 .)

Overridden version of ToString was executed

This verifies that even though the reference to the object of the class B was stored in a reference variable of type Object , the overridden version of the ToString method in the class named B was executed (instead of the default version defined in the class named Object) . This is runtime polymorphic behavior , as described in a previous module.

Once again, what is the rule?

The selection of a method for execution is based on the actual type of object whose reference is stored in a reference variable, and not on the type of the reference variable on which the method is called.

An object of the class C

Finally, the code in Listing 6

  • Instantiates a new object of the class C
  • Stores the object's reference in a reference variable of type Object
  • Calls the ToString method on the reference and saves the returned string
  • Displays the returned string on the computer screen

Listing 6 . An object of the class C.

Object varC = new C(); String v3 = varC.ToString();Console.WriteLine(v3); //Pause until user presses any key.Console.ReadKey();}//end Main }//end class Polymorph04

What will the output look like?

By now, you should know what to expect in the way of text appearing on the computer screen. The code in Listing 6 causes the text shown in Figure 3 to be displayed.

Figure 3 . Text output for overridden ToString method and class C.

ToString in class C

Overridden version of ToString was called

This confirms what you should already have known by now. In particular, even though the reference to the object of the class C was stored in a reference variable of type Object , the overridden version of the ToString method defined in the class named C was executed. Again, this is runtime polymorphic behavior based on class inheritance and method overriding.

No downcasting was required

It is also very important to note that no downcasting was required in order to call the ToString method in any of the cases shown above.

Because a default version of the ToString method is defined in the Object class, that method can be called without a requirement for downcasting on a reference to any object stored in a variable oftype Object . This holds true for any of the methods defined in the class named Object .

A generic array object

Therefore, if we create an array object designed to store references of type Object , we can store (potentially mixed) references to any type of object in that array. We can later call any of the methods definedin the Object class on any of the references stored in the array.

The result will be the execution of the overridden version of the method as defined in the class from which the object was instantiated, or the versioninherited into that class if the method is not overridden in that class. Current jargon would say that the behavior of the method is appropriate for the type of object on which it is called.

Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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.
Bharti
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
Daniel
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
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
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.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Xna game studio. OpenStax CNX. Feb 28, 2014 Download for free at https://legacy.cnx.org/content/col11634/1.6
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Xna game studio' conversation and receive update notifications?

Ask