<< Chapter < Page Chapter >> Page >

An inherited virtual method can be overridden by every class that inherits it, resulting in potentially many differentoverridden versions of a given method in a class hierarchy.

Listing 3 . Definition of class C.

class C : B { public override String ToString() {return "ToString in class C"; }//end overridden ToString()}//end class B

Behavior of overridden version

The behavior of this overridden version of the method is similar to, but different from the overridden version in the class B.

In this case, the method returns a reference to a String object that can be used to confirm that this overridden version of the methodhas been executed.

The driver class

Listing 4 shows the beginning of the driver class named Polymorph04 .

Listing 4 . Beginning of the driver class.

public class Polymorph04 { public static void Main() {Object varA = new A(); String v1 = varA.ToString();Console.WriteLine(v1);

A new object of the class A

The Main method of the driver class begins by instantiating a new object of the class A, and saving the object's reference in a reference variable of type Object , named varA .

It is very important to note that even though the object was instantiated from the class named A , the reference was saved as type Object , not type A.

Call ToString method on the reference

Then the code in Listing 4 calls the ToString method on the reference variable named varA , saving the returned reference to the String object in a reference variable of type String named v1 .

Display the returned String

Finally, that reference is passed to the WriteLine method, causing the String returned by the ToString method to be displayed on the computer screen. This causes the text shown in Figure 1 to be displayed.

Figure 1 . Text output for ToString method and class A.

A

Default ToString behavior

What you are seeing here is the String produced by the default version of the ToString method, as defined by the class named Object . The default implementation of the ToString method returns the fully qualified name of the type of the object. In this case, the object was instantiated from the class named A (so the type of the object is A ) .

Class A does not override ToString

Recall that our new class named A does not override the ToString method. Therefore, when the ToString method is called on a reference to an object of the class A, the default version of the method is executed, producing the output shown in Figure 1 .

A new object of the class B

Now consider the code shown in Listing 5 , which instantiates a new object of the class named B , and stores the object's reference in a reference variable of type Object .

Listing 5 . A new object of the class B.

Object varB = new B(); String v2 = varB.ToString();Console.WriteLine(v2);

Call ToString and display the result

The code in Listing 5 calls the ToString method on the reference of type Object , saving the returned reference in the reference variable named v2 . (Recall that the ToString method is overridden in the class named B .)

As before, the reference is passed to the WriteLine method, which causes the text shown in Figure 2 to be displayed on the computer screen.

Questions & Answers

how can chip be made from sand
Eke Reply
are nano particles real
Missy Reply
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
Lohitha
where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
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
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 Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




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
Anindyo Mukhopadhyay
Start Quiz
Nicole Bartels
Start Quiz
Yasser Ibrahim
Start Quiz
Madison Christian
Start Exam
Eric Crawford
Start Quiz